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Lucidi M, Visaggio D, Migliaccio A, Capecchi G, Visca P, Imperi F, Zarrilli R. Pathogenicity and virulence of Acinetobacter baumannii: Factors contributing to the fitness in healthcare settings and the infected host. Virulence 2024; 15:2289769. [PMID: 38054753 PMCID: PMC10732645 DOI: 10.1080/21505594.2023.2289769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 11/27/2023] [Indexed: 12/07/2023] Open
Abstract
Acinetobacter baumannii is a common cause of healthcare-associated infections and hospital outbreaks, particularly in intensive care units. Much of the success of A. baumannii relies on its genomic plasticity, which allows rapid adaptation to adversity and stress. The capacity to acquire novel antibiotic resistance determinants and the tolerance to stresses encountered in the hospital environment promote A. baumannii spread among patients and long-term contamination of the healthcare setting. This review explores virulence factors and physiological traits contributing to A. baumannii infection and adaptation to the hospital environment. Several cell-associated and secreted virulence factors involved in A. baumannii biofilm formation, cell adhesion, invasion, and persistence in the host, as well as resistance to xeric stress imposed by the healthcare settings, are illustrated to give reasons for the success of A. baumannii as a hospital pathogen.
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Affiliation(s)
- Massimiliano Lucidi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | | | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
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2
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Song S, Yang S, Zheng R, Yin D, Cao Y, Wang Y, Qiao L, Bai R, Wang S, Yin W, Dong Y, Bai L, Yang H, Shen J, Wu C, Hu F, Wang Y. Adaptive evolution of carbapenem-resistant hypervirulent Klebsiella pneumoniae in the urinary tract of a single patient. Proc Natl Acad Sci U S A 2024; 121:e2400446121. [PMID: 39150777 DOI: 10.1073/pnas.2400446121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 06/26/2024] [Indexed: 08/18/2024] Open
Abstract
The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) is a growing concern due to its high mortality and limited treatment options. Although hypermucoviscosity is crucial for CR-hvKp infection, the role of changes in bacterial mucoviscosity in the host colonization and persistence of CR-hvKp is not clearly defined. Herein, we observed a phenotypic switch of CR-hvKp from a hypermucoviscous to a hypomucoviscous state in a patient with scrotal abscess and urinary tract infection (UTI). This switch was attributed to decreased expression of rmpADC, the regulator of mucoid phenotype, caused by deletion of the upstream insertion sequence ISKpn26. Postswitching, the hypomucoid variant showed a 9.0-fold decrease in mice sepsis mortality, a >170.0-fold reduction in the ability to evade macrophage phagocytosis in vitro, and an 11.2- to 40.9-fold drop in growth rate in normal mouse serum. Conversely, it exhibited an increased residence time in the mouse urinary tract (21 vs. 6 d), as well as a 216.4-fold boost in adhesion to bladder epithelial cells and a 48.7% enhancement in biofilm production. Notably, the CR-hvKp mucoid switch was reproduced in an antibiotic-free mouse UTI model. The in vivo generation of hypomucoid variants was primarily associated with defective or low expression of rmpADC or capsule synthesis gene wcaJ, mediated by ISKpn26 insertion/deletion or base-pair insertion. The spontaneous hypomucoid variants also outcompeted hypermucoid bacteria in the mouse urinary tract. Collectively, the ISKpn26-associated mucoid switch in CR-hvKp signifies the antibiotic-independent host adaptive evolution, providing insights into the role of mucoid switch in the persistence of CR-hvKp.
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Affiliation(s)
- Shikai Song
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
- Poultry Research Institute, Shandong Academy of Agricultural Science, Jinan 250100, Shandong, China
| | - Shixin Yang
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Ruicheng Zheng
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Dandan Yin
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai 200433, China
| | - Yue Cao
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Yao Wang
- Shandong Animal Disease Prevention and Control Center, Jinan 250100, Shandong, China
| | - Lu Qiao
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Rina Bai
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Shuge Wang
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Wenjuan Yin
- Department of Microbiology and Immunology, College of Basic Medical Science, Key Laboratory of Pathogenesis Mechanism and Control of Inflammatory-Autoimmune Diseases of Hebei Province, Hebei University, Baoding 071002, China
| | - Yanjun Dong
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Li Bai
- National Center for Food Safety Risk Assessment, Beijing 100022, China
| | - Hui Yang
- National Center for Food Safety Risk Assessment, Beijing 100022, China
| | - Jianzhong Shen
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Congming Wu
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Fupin Hu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai 200433, China
| | - Yang Wang
- National Key Laboratory of Veterinary Public Health and Safety, Department of Basic Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
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3
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Kungwani NA, Panda J, Mishra AK, Chavda N, Shukla S, Vikhe K, Sharma G, Mohanta YK, Sharifi-Rad M. Combating bacterial biofilms and related drug resistance: Role of phyto-derived adjuvant and nanomaterials. Microb Pathog 2024; 195:106874. [PMID: 39181190 DOI: 10.1016/j.micpath.2024.106874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 08/16/2024] [Accepted: 08/19/2024] [Indexed: 08/27/2024]
Abstract
The emergence of antimicrobial resistance (AMR) in clinical microbes has led to a search for novel antibiotics for combating bacterial infections. The treatment of bacterial infections becomes more challenging with the onset of biofilm formation. AMR is further accelerated by biofilm physiology and differential gene expression in bacteria with an inherent resistance to conventional antibiotics. In the search for innovative strategies to control the spread of AMR in clinical isolates, plant-derived therapeutic metabolites can be repurposed to control biofilm-associated drug resistance. Unlike antibiotics, designed to act on a single cellular process, phytochemicals can simultaneously target multiple cellular components. Furthermore, they can disrupt biofilm formation and inhibit quorum sensing, offering a comprehensive approach to combat bacterial infections. In bacterial biofilms, the first line of AMR is due to biofilms associated with the extracellular matrix, diffusion barriers, quorum sensing, and persister cells. These extracellular barriers can be overcome using phytochemical-based antibiotic adjuvants to increase the efficacy of antibiotic treatment and restrict the spread of AMR. Furthermore, phytochemicals can be used to target bacterial intracellular machinery such as DNA replication, protein synthesis, efflux pumps, and degrading enzymes. In parallel with pristine phytochemicals, phyto-derived nanomaterials have emerged as an effective means of fighting bacterial biofilms. These nanomaterials can be formulated to cross the biofilm barriers and function on cellular targets. This review focuses on the synergistic effects of phytochemicals and phyto-derived nanomaterials in controlling the progression of biofilm-related AMR. IT provides comprehensive insights into recent advancements and the underlying mechanisms of the use of phyto-derived adjuvants and nanomaterials.
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Affiliation(s)
- Neelam Amit Kungwani
- Department of Environmental Biotechnology, Gujarat Biotechnology University, Gandhinagar, Gujarat, 382355, India.
| | - Jibanjyoti Panda
- Nano-biotechnology and Translational Knowledge Laboratory, Department of Applied Biology, School of Biological Sciences, University of Science and Technology Meghalaya, Techno City, 9th Mile, Baridua, Ri-Bhoi, 793101, Meghalaya, India
| | - Awdhesh Kumar Mishra
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk, 38541, Republic of Korea
| | | | - Sudhir Shukla
- Homi Bhabha National Institute, Biofouling and Biofilm Processes Section, WSCD, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, Tamilnadu, 603102, India
| | - Kalyani Vikhe
- Department of Environmental Biotechnology, Gujarat Biotechnology University, Gandhinagar, Gujarat, 382355, India
| | - Gunjan Sharma
- Department of Plant Biotechnology, Gujarat Biotechnology University, Gandhinagar, Gujarat, 382355, India
| | - Yugal Kishore Mohanta
- Nano-biotechnology and Translational Knowledge Laboratory, Department of Applied Biology, School of Biological Sciences, University of Science and Technology Meghalaya, Techno City, 9th Mile, Baridua, Ri-Bhoi, 793101, Meghalaya, India; Centre for Herbal Pharmacology and Environmental Sustainability, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, 603103, Tamil Nadu, India.
| | - Majid Sharifi-Rad
- Department of Range and Watershed Management, Faculty of Water and Soil, University of Zabol, Zabol, 98613-35856, Iran.
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Cooper C, Legood S, Wheat RL, Forrest D, Sharma P, Haycocks JRJ, Grainger DC. H-NS is a bacterial transposon capture protein. Nat Commun 2024; 15:7137. [PMID: 39164300 PMCID: PMC11335895 DOI: 10.1038/s41467-024-51407-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 08/05/2024] [Indexed: 08/22/2024] Open
Abstract
The histone-like nucleoid structuring (H-NS) protein is a DNA binding factor, found in gammaproteobacteria, with functional equivalents in diverse microbes. Universally, such proteins are understood to silence transcription of horizontally acquired genes. Here, we identify transposon capture as a major overlooked function of H-NS. Using genome-scale approaches, we show that H-NS bound regions are transposition "hotspots". Since H-NS often interacts with pathogenicity islands, such targeting creates clinically relevant phenotypic diversity. For example, in Acinetobacter baumannii, we identify altered motility, biofilm formation, and interactions with the human immune system. Transposon capture is mediated by the DNA bridging activity of H-NS and, if absent, more ubiquitous transposition results. Consequently, transcribed and essential genes are disrupted. Hence, H-NS directs transposition to favour evolutionary outcomes useful for the host cell.
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Affiliation(s)
- Charles Cooper
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Simon Legood
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Rachel L Wheat
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - David Forrest
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Prateek Sharma
- School of Biosciences, University of Birmingham, Birmingham, UK
| | | | - David C Grainger
- School of Biosciences, University of Birmingham, Birmingham, UK.
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5
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Hamrock FJ, Ryan D, Shaibah A, Ershova AS, Mogre A, Sulimani MM, Ben Taarit S, Reichardt S, Hokamp K, Westermann AJ, Kröger C. Global analysis of the RNA-RNA interactome in Acinetobacter baumannii AB5075 uncovers a small regulatory RNA repressing the virulence-related outer membrane protein CarO. Nucleic Acids Res 2024:gkae668. [PMID: 39149883 DOI: 10.1093/nar/gkae668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 07/11/2024] [Accepted: 07/19/2024] [Indexed: 08/17/2024] Open
Abstract
Acinetobacter baumannii is an opportunistic Gram-negative pathogen that infects critically ill patients. The emergence of antimicrobial resistant A. baumannii has exacerbated the need to characterize environmental adaptation, antibiotic resistance and pathogenicity and their genetic regulators to inform intervention strategies. Critical to adaptation to changing environments in bacteria are small regulatory RNAs (sRNAs), however, the role that sRNAs play in the biology of A. baumannii is poorly understood. To assess the regulatory function of sRNAs and to uncover their RNA interaction partners, we employed an RNA proximity ligation and sequencing method (Hi-GRIL-seq) in three different environmental conditions. Forty sRNAs were ligated to sRNA-RNA chimeric sequencing reads, suggesting that sRNA-mediated gene regulation is pervasive in A. baumannii. In-depth characterization uncovered the sRNA Aar to be a post-transcriptional regulator of four mRNA targets including the transcript encoding outer membrane protein CarO. Aar initiates base-pairing with these mRNAs using a conserved seed region of nine nucleotides, sequestering the ribosome binding sites and inhibiting translation. Aar is differentially expressed in multiple stress conditions suggesting a role in fine-tuning translation of the Aar-target molecules. Our study provides mechanistic insights into sRNA-mediated gene regulation in A. baumannii and represents a valuable resource for future RNA-centric research endeavours.
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Affiliation(s)
- Fergal J Hamrock
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Daniel Ryan
- Department of Microbiology, Biocentre, University of Würzburg, Würzburg, Germany
| | - Ali Shaibah
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Anna S Ershova
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Aalap Mogre
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Maha M Sulimani
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Safa Ben Taarit
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Sarah Reichardt
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Karsten Hokamp
- Department of Genetics, School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Alexander J Westermann
- Department of Microbiology, Biocentre, University of Würzburg, Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Carsten Kröger
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
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Męcik M, Stefaniak K, Harnisz M, Korzeniewska E. Hospital and municipal wastewater as a source of carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa in the environment: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:48813-48838. [PMID: 39052110 PMCID: PMC11310256 DOI: 10.1007/s11356-024-34436-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 07/16/2024] [Indexed: 07/27/2024]
Abstract
The increase in the prevalence of carbapenem-resistant Gram-negative bacteria, in particular Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPA), poses a serious threat for public health worldwide. This article reviews the alarming data on the prevalence of infections caused by CRAB and CRPA pathogens and their presence in hospital and municipal wastewater, and it highlights the environmental impact of antibiotic resistance. The article describes the key role of antibiotic resistance genes (ARGs) in the acquisition of carbapenem resistance and sheds light on bacterial resistance mechanisms. The main emphasis was placed on the transfer of ARGs not only in the clinical setting, but also in the environment, including water, soil, and food. The aim of this review was to expand our understanding of the global health risks associated with CRAB and CRPA in hospital and municipal wastewater and to analyze the spread of these micropollutants in the environment. A review of the literature published in the last decade will direct research on carbapenem-resistant pathogens, support the implementation of effective preventive measures and interventions, and contribute to the development of improved strategies for managing this problem.
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Affiliation(s)
- Magdalena Męcik
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720, Olsztyn, Poland
| | - Kornelia Stefaniak
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720, Olsztyn, Poland
| | - Monika Harnisz
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720, Olsztyn, Poland
| | - Ewa Korzeniewska
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720, Olsztyn, Poland.
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7
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Lee GY, Song J. Single missense mutations in Vi capsule synthesis genes confer hypervirulence to Salmonella Typhi. Nat Commun 2024; 15:5258. [PMID: 38898034 PMCID: PMC11187135 DOI: 10.1038/s41467-024-49590-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 06/07/2024] [Indexed: 06/21/2024] Open
Abstract
Many bacterial pathogens, including the human exclusive pathogen Salmonella Typhi, express capsular polysaccharides as a crucial virulence factor. Here, through S. Typhi whole genome sequence analyses and functional studies, we found a list of single point mutations that make S. Typhi hypervirulent. We discovered a single point mutation in the Vi biosynthesis enzymes that control Vi polymerization or acetylation is enough to result in different capsule variants of S. Typhi. All variant strains are pathogenic, but the hyper Vi capsule variants are particularly hypervirulent, as demonstrated by the high morbidity and mortality rates observed in infected mice. The hypo Vi capsule variants have primarily been identified in Africa, whereas the hyper Vi capsule variants are distributed worldwide. Collectively, these studies increase awareness about the existence of different capsule variants of S. Typhi, establish a solid foundation for numerous future studies on S. Typhi capsule variants, and offer valuable insights into strategies to combat capsulated bacteria.
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Affiliation(s)
- Gi Young Lee
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY, 14853, USA
| | - Jeongmin Song
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY, 14853, USA.
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Wang W, Qiu Z, Li H, Wu X, Cui Y, Xie L, Chang B, Li P, Zeng H, Ding T. Patient-derived pathogenic microbe deposition enhances exposure risk in pediatric clinics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 924:171703. [PMID: 38490424 DOI: 10.1016/j.scitotenv.2024.171703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 03/11/2024] [Accepted: 03/12/2024] [Indexed: 03/17/2024]
Abstract
Healthcare-associated infections (HAIs) pose significant risks to pediatric patients in outpatient settings. To prevent HAIs, understanding the sources and transmission routes of pathogenic microorganisms is crucial. This study aimed to identify the sources of opportunistic bacterial pathogens (OBPs) in pediatric outpatient settings and determine their transmission routes. Furthermore, assessing the public health risks associated with the core OBPs is important. We collected 310 samples from various sites in pediatric outpatient areas and quantified the bacteria using qPCR and CFU counting. We also performed 16S rRNA gene and single-bacterial whole-genome sequencing to profile the transmission routes and antibiotic resistance characteristics of OBPs. We observed significant variations in microbial diversity and composition among sampling sites in pediatric outpatient settings, with active communication of the microbiota between linked areas. We found that the primary source of OBPs in multi-person contact areas was the hand surface, particularly in pediatric patients. Five core OBPs, Staphylococcus epidermidis, Acinetobacter baumannii, Pseudomonas aeruginosa, Streptococcus mitis, and Streptococcus oralis, were mainly derived from pediatric patients and spread into the environment. These OBPs accumulated at multi-person contact sites, resulting in high microbial diversity in these areas. Transmission tests confirmed the challenging spread of these pathogens, with S. epidermidis transferring from the patient's hand to the environment, leading to an increased abundance and emergence of related strains. More importantly, S. epidermidis isolated from pediatric patients carried more antibiotic-resistance genes. In addition, two strains of multidrug-resistant A. baumannii were isolated from both a child and a parent, confirming the transmission of the five core OBPs centered around pediatric patients and multi-person contact areas. Our results demonstrate that pediatric patients serve as a significant source of OBPs in pediatric outpatient settings. OBPs carried by pediatric patients pose a high public health risk. To effectively control HAIs, increasing hand hygiene measures in pediatric patients and enhancing the frequency of disinfection in multi-person contact areas remains crucial. By targeting these preventive measures, the spread of OBPs can be reduced, thereby mitigating the risk of HAIs in pediatric outpatient settings.
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Affiliation(s)
- Wan Wang
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Zongyao Qiu
- Center for Disease Control and Prevention of Nanhai District, Foshan 528200, China
| | - Hui Li
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Xiaorong Wu
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Ying Cui
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Lixiang Xie
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Bozhen Chang
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Peipei Li
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China
| | - Hong Zeng
- Center for Disease Control and Prevention of Nanhai District, Foshan 528200, China.
| | - Tao Ding
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China.
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9
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Xiao N, Li Y, Lin H, Yang J, Xiao G, Jiang Z, Zhang Y, Chen W, Zhou P, Sun Z, Li J. Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli in Animal Farms in Hunan Province, China. Microorganisms 2024; 12:653. [PMID: 38674598 PMCID: PMC11051881 DOI: 10.3390/microorganisms12040653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
Multi-drug resistance of bacteria producing extended-spectrum β-lactamase (ESBL) is a public health challenge. Thus, this study aimed to investigate the antimicrobial susceptibility of ESBL-producing Escherichia coli (ESBL-EC) in Hunan Province, China. A total of 1366 fecal samples were collected from pig, chicken, and cattle farms over a six-year period, which were assessed using strain isolation, 16S rRNA identification, polymerase chain reaction, drug sensitivity testing, whole-genome sequencing, and bioinformatics analysis. The results showed an overall prevalence of 6.66% for ESBL-EC strains, with ESBL positivity extents for pigs, chickens, and cattle isolates at 6.77%, 6.54%, and 12.5%, respectively. Most ESBL-EC isolates were resistant to cefotaxime, tetracycline, and trimethoprim-sulfamethoxazole; however, all the isolates were susceptible to meropenem, with relatively low resistance to amikacin and tigecycline. Various multi-locus sequence types with different origins and similar affinities were identified, with ST155 (n = 16) being the most common subtype. Several types of resistance genes were identified among the 91 positive strains, with beta-lactamase blaCTX-M-55 being the most common ESBL genotype. IncFIB was the predominant plasmid type. Widespread use of antibiotics in animal farming may increase antibiotic resistance, posing a serious threat to the health of farmed animals and, thus, to human food security and health.
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Affiliation(s)
- Ning Xiao
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Yujuan Li
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Hongguang Lin
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
- Institute of Biopharmaceutical and Health Engineering, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Jie Yang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Gang Xiao
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Zonghan Jiang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Yunqiang Zhang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Wenxin Chen
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Pengcheng Zhou
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
| | - Zhiliang Sun
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
| | - Jiyun Li
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China; (N.X.); (J.Y.); (G.X.); (Z.J.); (Y.Z.); (W.C.); (P.Z.)
- Hunan Engineering Technology Research Center of Veterinary Drugs, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (H.L.)
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10
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Menon ND, Poudel S, Sastry AV, Rychel K, Szubin R, Dillon N, Tsunemoto H, Hirose Y, Nair BG, Kumar GB, Palsson BO, Nizet V. Independent component analysis reveals 49 independently modulated gene sets within the global transcriptional regulatory architecture of multidrug-resistant Acinetobacter baumannii. mSystems 2024; 9:e0060623. [PMID: 38189271 PMCID: PMC10878099 DOI: 10.1128/msystems.00606-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 11/29/2023] [Indexed: 01/09/2024] Open
Abstract
Acinetobacter baumannii causes severe infections in humans, resists multiple antibiotics, and survives in stressful environmental conditions due to modulations of its complex transcriptional regulatory network (TRN). Unfortunately, our global understanding of the TRN in this emerging opportunistic pathogen is limited. Here, we apply independent component analysis, an unsupervised machine learning method, to a compendium of 139 RNA-seq data sets of three multidrug-resistant A. baumannii international clonal complex I strains (AB5075, AYE, and AB0057). This analysis allows us to define 49 independently modulated gene sets, which we call iModulons. Analysis of the identified A. baumannii iModulons reveals validating parallels to previously defined biological operons/regulons and provides a framework for defining unknown regulons. By utilizing the iModulons, we uncover potential mechanisms for a RpoS-independent general stress response, define global stress-virulence trade-offs, and identify conditions that may induce plasmid-borne multidrug resistance. The iModulons provide a model of the TRN that emphasizes the importance of transcriptional regulation of virulence phenotypes in A. baumannii. Furthermore, they suggest the possibility of future interventions to guide gene expression toward diminished pathogenic potential.IMPORTANCEThe rise in hospital outbreaks of multidrug-resistant Acinetobacter baumannii infections underscores the urgent need for alternatives to traditional broad-spectrum antibiotic therapies. The success of A. baumannii as a significant nosocomial pathogen is largely attributed to its ability to resist antibiotics and survive environmental stressors. However, there is limited literature available on the global, complex regulatory circuitry that shapes these phenotypes. Computational tools that can assist in the elucidation of A. baumannii's transcriptional regulatory network architecture can provide much-needed context for a comprehensive understanding of pathogenesis and virulence, as well as for the development of targeted therapies that modulate these pathways.
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Affiliation(s)
- Nitasha D. Menon
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, California, USA
| | - Saugat Poudel
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Anand V. Sastry
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Kevin Rychel
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Richard Szubin
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Nicholas Dillon
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, California, USA
- Department of Biological Sciences, University of Texas at Dallas, Dallas, Texas, USA
| | - Hannah Tsunemoto
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA
| | - Yujiro Hirose
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, California, USA
- Department of Microbiology, Graduate School of Dentistry, Osaka University, Suita, Osaka, Japan
| | - Bipin G. Nair
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Geetha B. Kumar
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Bernhard O. Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, California, USA
| | - Victor Nizet
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, California, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
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11
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Mushtaq F, Nadeem A, Yabrag A, Bala A, Karah N, Zlatkov N, Nyunt Wai S, Uhlin BE, Ahmad I. Colony phase variation switch modulates antimicrobial tolerance and biofilm formation in Acinetobacter baumannii. Microbiol Spectr 2024; 12:e0295623. [PMID: 38205963 PMCID: PMC10845969 DOI: 10.1128/spectrum.02956-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 12/09/2023] [Indexed: 01/12/2024] Open
Abstract
Carbapenem-resistant Acinetobacter baumannii causes one of the most difficult-to-treat nosocomial infections. Polycationic drugs like polymyxin B or colistin and tetracycline drugs such as doxycycline or minocycline are commonly used to treat infections caused by carbapenem-resistant A. baumannii. Here, we show that a subpopulation of cells associated with the opaque/translucent colony phase variation by A. baumannii AB5075 displays differential tolerance to subinhibitory concentrations of colistin and tetracycline. Using a variety of microscopic techniques, we demonstrate that extracellular polysaccharide moieties mediate colistin tolerance to opaque A. baumannii at single-cell level and that mushroom-shaped biofilm structures protect opaque bacteria at the community level. The colony switch phenotype is found to alter several traits of A. baumannii, including long-term survival under desiccation, tolerance to ethanol, competition with Escherichia coli, and intracellular survival in the environmental model host Acanthamoeba castellanii. Additionally, our findings suggest that extracellular DNA associated with membrane vesicles can promote colony switching in a DNA recombinase-dependent manner.IMPORTANCEAs a WHO top-priority drug-resistant microbe, Acinetobacter baumannii significantly contributes to hospital-associated infections worldwide. One particularly intriguing aspect is its ability to reversibly switch its colony morphotype on agar plates, which has been remarkably underexplored. In this study, we employed various microscopic techniques and phenotypic assays to investigate the colony phase variation switch under different clinically and environmentally relevant conditions. Our findings reveal that the presence of a poly N-acetylglucosamine-positive extracellular matrix layer contributes to the protection of bacteria from the bactericidal effects of colistin. Furthermore, we provide intriguing insights into the multicellular lifestyle of A. baumannii, specifically in the context of colony switch variation within its predatory host, Acanthamoeba castellanii.
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Affiliation(s)
- Fizza Mushtaq
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Aftab Nadeem
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Abdelbasset Yabrag
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Anju Bala
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nabil Karah
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Irfan Ahmad
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
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12
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Pérez-Varela M, Singh R, Colquhoun JM, Starich OG, Tierney ARP, Tipton KA, Rather PN. Evidence for Rho-dependent control of a virulence switch in Acinetobacter baumannii. mBio 2024; 15:e0270823. [PMID: 38085026 PMCID: PMC10790780 DOI: 10.1128/mbio.02708-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 12/31/2023] Open
Abstract
IMPORTANCE Acinetobacter baumannii is a significant cause of infections in the healthcare setting. More recently, A. baumannii has been a leading cause of secondary bacterial pneumonia in patients infected with SARS-CoV-2 and the overall frequency of A. baumannii infection increased 78% during the COVID-19 pandemic. A. baumannii can exist in virulent or avirulent subpopulations and this interconversion is mediated by the expression of a family of TetR-type transcriptional regulators. In this study, we demonstrate that Rho is a key regulatory component in the expression of these TetR regulators. Overall, this study is the first to address a role for Rho in A. baumannii and provides additional evidence for the role of Rho in regulating diversity in bacterial subpopulations.
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Affiliation(s)
- María Pérez-Varela
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Raja Singh
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Jennifer M. Colquhoun
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
| | - Olivia G. Starich
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Aimee R. P. Tierney
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Kyle A. Tipton
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
| | - Philip N. Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
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13
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Lee GY, Song J. Single missense mutations in Vi capsule synthesis genes confer hypervirulence to Salmonella Typhi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.28.573590. [PMID: 38260632 PMCID: PMC10802248 DOI: 10.1101/2023.12.28.573590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Many bacterial pathogens, including the human exclusive pathogen Salmonella Typhi, express capsular polysaccharides as a crucial virulence factor. Here, through S. Typhi whole genome sequence analyses and functional studies, we found a list of single point mutations that make S . Typhi hypervirulent. We discovered a single point mutation in the Vi biosynthesis enzymes that control the length or acetylation of Vi is enough to create different capsule variants of S. Typhi. All variant strains are pathogenic, but the hyper-capsule variants are particularly hypervirulent, as demonstrated by the high morbidity and mortality rates observed in infected mice. The hypo-capsule variants have primarily been identified in Africa, whereas the hyper-capsule variants are distributed worldwide. Collectively, these studies increase awareness about the existence of different capsule variants of S. Typhi, establish a solid foundation for numerous future studies on S. Typhi capsule variants, and offer valuable insights into strategies to combat capsulated bacteria.
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14
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Maure A, Robino E, Van der Henst C. The intracellular life of Acinetobacter baumannii. Trends Microbiol 2023; 31:1238-1250. [PMID: 37487768 DOI: 10.1016/j.tim.2023.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/26/2023]
Abstract
Acinetobacter baumannii is a Gram-negative opportunistic bacterium responsible for nosocomial and community-acquired infections. This pathogen is globally disseminated and associated with high levels of antibiotic resistance, which makes it an important threat to human health. Recently, new evidence showed that several A. baumannii isolates can survive and proliferate within eukaryotic professional and/or nonprofessional phagocytic cells, with in vivo consequences. This review provides updated information and describes the tools that A. baumannii possesses to adhere, colonize, and replicate in host cells. Additionally, we emphasize the high genetic and phenotypic heterogeneity detected amongst A. baumannii isolates and its impact on the bacterial intracellular features. We also discuss the need for standardized methods to characterize this pathogen robustly and consequently consider some strains as facultative intracellular bacteria.
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Affiliation(s)
- Alexandra Maure
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Etienne Robino
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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15
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Jiao M, He W, Ouyang Z, Qin Q, Guo Y, Zhang J, Bai Y, Guo X, Yu Q, She J, Hwang PM, Zheng F, Wen Y. Mechanistic and structural insights into the bifunctional enzyme PaaY from Acinetobacter baumannii. Structure 2023; 31:935-947.e4. [PMID: 37329879 DOI: 10.1016/j.str.2023.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/28/2023] [Accepted: 05/23/2023] [Indexed: 06/19/2023]
Abstract
PaaY is a thioesterase that enables toxic metabolites to be degraded through the bacterial phenylacetic acid (PA) pathway. The Acinetobacter baumannii gene FQU82_01591 encodes PaaY, which we demonstrate to possess γ-carbonic anhydrase activity in addition to thioesterase activity. The crystal structure of AbPaaY in complex with bicarbonate reveals a homotrimer with a canonical γ-carbonic anhydrase active site. Thioesterase activity assays demonstrate a preference for lauroyl-CoA as a substrate. The AbPaaY trimer structure shows a unique domain-swapped C-termini, which increases the stability of the enzyme in vitro and decreases its susceptibility to proteolysis in vivo. The domain-swapped C-termini impact thioesterase substrate specificity and enzyme efficacy without affecting carbonic anhydrase activity. AbPaaY knockout reduced the growth of Acinetobacter in media containing PA, decreased biofilm formation, and impaired hydrogen peroxide resistance. Collectively, AbPaaY is a bifunctional enzyme that plays a key role in the metabolism, growth, and stress response mechanisms of A. baumannii.
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Affiliation(s)
- Min Jiao
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Wenbo He
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Zhenlin Ouyang
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Qian Qin
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yucheng Guo
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Jiaxin Zhang
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yixin Bai
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Xiaolong Guo
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Qinyue Yu
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Junjun She
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China
| | - Peter M Hwang
- Departments of Medicine and Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Fang Zheng
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China
| | - Yurong Wen
- Center for Microbiome Research of Med-X Institute, Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, China; The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an 710061, China.
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16
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Maharjan RP, Sullivan GJ, Adams F, Shah B, Hawkey J, Delgado N, Semenec L, Dinh H, Li L, Short F, Parkhill J, Paulsen I, Barquist L, Eijkelkamp B, Cain A. DksA is a conserved master regulator of stress response in Acinetobacter baumannii. Nucleic Acids Res 2023; 51:6101-6119. [PMID: 37158230 PMCID: PMC10325922 DOI: 10.1093/nar/gkad341] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 04/11/2023] [Accepted: 05/04/2023] [Indexed: 05/10/2023] Open
Abstract
Coordination of bacterial stress response mechanisms is critical for long-term survival in harsh environments for successful host infection. The general and specific stress responses of well-studied Gram-negative pathogens like Escherichia coli are controlled by alternative sigma factors, archetypically RpoS. The deadly hospital pathogen Acinetobacter baumannii is notoriously resistant to environmental stresses, yet it lacks RpoS, and the molecular mechanisms driving this incredible stress tolerance remain poorly defined. Here, using functional genomics, we identified the transcriptional regulator DksA as a master regulator for broad stress protection and virulence in A. baumannii. Transcriptomics, phenomics and in vivo animal studies revealed that DksA controls ribosomal protein expression, metabolism, mutation rates, desiccation, antibiotic resistance, and host colonization in a niche-specific manner. Phylogenetically, DksA was highly conserved and well-distributed across Gammaproteobacteria, with 96.6% containing DksA, spanning 88 families. This study lays the groundwork for understanding DksA as a major regulator of general stress response and virulence in this important pathogen.
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Affiliation(s)
- Ram P Maharjan
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Geraldine J Sullivan
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Felise G Adams
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - Bhumika S Shah
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Jane Hawkey
- Department of Infectious Diseases, Central Clinical School, Monash University, Victoria, Australia
| | - Natasha Delgado
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Lucie Semenec
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Hue Dinh
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Liping Li
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Francesca L Short
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC3800, Australia
| | - Julian Parkhill
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Ian T Paulsen
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Lars Barquist
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080Würzburg, Germany
- Faculty of Medicine, University of Würzburg, 97080Würzburg, Germany
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - Amy K Cain
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
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17
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Xiao S, Mi J, Chen Y, Feng K, Mei L, Liao X, Wu Y, Wang Y. The abundance and diversity of antibiotic resistance genes in layer chicken ceca is associated with farm enviroment. Front Microbiol 2023; 14:1177404. [PMID: 37455745 PMCID: PMC10348872 DOI: 10.3389/fmicb.2023.1177404] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/18/2023] [Indexed: 07/18/2023] Open
Abstract
Industrialized layer chicken feedlots harbor complex environmental microbial communities that affect the enrichment and exchange of gut bacteria and antibiotic resistance genes (ARGs). However, the contribution of different environmental sources to the gut ARGs of layer chickens is not clear. Here, layer chicken gut and environmental samples (air, water, feed, cage, feather, maternal hen feces, uropygial glands) were collected during the early 3 month period before the laying of eggs, and the source and characteristics of the gut microorganisms and ARGs were analyzed by performing 16S rRNA and metagenomic sequencing. The results showed that the abundances of Bacteroidetes and Actinobacteria in cecum of layer chickens gradually increased, while that of Proteobacteria decreased with age, and the number and relative abundance of ARGs decreased significantly with age. On day 5, 57% of the layer chicken cecal ARGs were from feather samples, and 30% were from cage samples. Subsequently, the contribution of cage ARGs became progressively more prominent over time. At days 30 and 57, the contribution of cage ARGs to the chick cecal ARGs reached 63.3 and 69.5%, respectively. The bacterial community composition (especially the abundances of Klebsiella pneumoniae and Escherichia coli) was the major factor impacting the ARG profile. K. pneumoniae and E. coli were mainly transmitted from feathers to the layer chicken cecum, and the contribution rates were 32 and 3.4%, respectively. In addition, we observed the transmission of ARG-carrying bacteria (Bacteroides fragilis) from the cage to the gut, with a contribution rate of 11.5%. It is noteworthy that B. fragilis is an opportunistic pathogen that may cause diarrhea in laying hens. These results can provide reference data for the healthy breeding of layer chickens and the prevention and control of ARG pollution.
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Affiliation(s)
- Shasha Xiao
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Jiandui Mi
- College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yingxin Chen
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Kunxian Feng
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Liang Mei
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Xindi Liao
- College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yinbao Wu
- College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yan Wang
- College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Heyuan Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Heyuan, China
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18
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Colquhoun JM, Farokhyfar M, Anderson AC, Bethel CR, Bonomo RA, Clarke AJ, Rather PN. Collateral Changes in Cell Physiology Associated with ADC-7 β-Lactamase Expression in Acinetobacter baumannii. Microbiol Spectr 2023; 11:e0464622. [PMID: 37074187 PMCID: PMC10269689 DOI: 10.1128/spectrum.04646-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/15/2023] [Indexed: 04/20/2023] Open
Abstract
The ADC (AmpC) β-lactamase is universally present in the Acinetobacter baumannii chromosome, suggesting it may have a yet-to-be-identified cellular function. Using peptidoglycan composition analysis, we show that overexpressing the ADC-7 β-lactamase in A. baumannii drives changes consistent with altered l,d-transpeptidase activity. Based on this, we tested whether cells overexpressing ADC-7 would exhibit new vulnerabilities. As proof of principle, a screen of transposon insertions revealed that an insertion in the distal 3' end of canB, encoding carbonic anhydrase, resulted in a significant loss of viability when the adc-7 gene was overexpressed. A canB deletion mutant exhibited a more pronounced loss of viability than the transposon insertion, and this became amplified when cells overexpressed ADC-7. Interestingly, overexpression of the OXA-23 or TEM-1 β-lactamases also led to a pronounced loss of viability in cells with reduced carbonic anhydrase activity. In addition, we demonstrate that reduced CanB activity led to increased sensitivity to peptidoglycan synthesis inhibitors and to the carbonic anhydrase inhibitor ethoxzolamide. Furthermore, this strain exhibited a synergistic interaction with the peptidoglycan inhibitor fosfomycin and ethoxzolamide. Our results highlight the impact of ADC-7 overexpression on cell physiology and reveal that the essential carbonic anhydrase CanB may represent a novel target for antimicrobial agents that would exhibit increased potency against β-lactamase-overexpressing A. baumannii. IMPORTANCE Acinetobacter baumannii has become resistant to all classes of antibiotics, with β-lactam resistance responsible for the majority of treatment failures. New classes of antimicrobials are needed to treat this high-priority pathogen. This study had uncovered a new genetic vulnerability in β-lactamase-expressing A. baumannii, where reduced carbonic anhydrase activity becomes lethal. Inhibitors of carbonic anhydrase could represent a new method for treating A. baumannii infections.
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Affiliation(s)
- Jennifer M. Colquhoun
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
| | | | - Alexander C. Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Christopher R. Bethel
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
| | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs, Cleveland, Ohio, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Case Western Reserve University, Cleveland, Ohio, USA
| | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Philip N. Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
- Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
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19
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Leukert L, Tietgen M, Krause FF, Schultze TG, Fuhrmann DC, Debruyne C, Salcedo SP, Visekruna A, Wittig L, Göttig S. Infection of Endothelial Cells with Acinetobacter baumannii Reveals Remodelling of Mitochondrial Protein Complexes. Microbiol Spectr 2023; 11:e0517422. [PMID: 37052493 PMCID: PMC10269660 DOI: 10.1128/spectrum.05174-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/17/2023] [Indexed: 04/14/2023] Open
Abstract
Acinetobacter baumannii is an antibiotic-resistant, Gram-negative pathogen that causes a multitude of nosocomial infections. However, pathogenicity mechanisms and the host cell response during infection remain unclear. In this study, we determined virulence traits of A. baumannii clinical isolates belonging to the most widely disseminated international clonal lineage, international cluster 2 (IC2), in vitro and in vivo. Complexome profiling of primary human endothelial cells with A. baumannii revealed that mitochondria, and in particular complexes of the electron transport chain, are important host cell targets. Infection with highly virulent A. baumannii remodelled assembly of mitochondrial protein complexes and led to metabolic adaptation. These were characterized by reduced mitochondrial respiration and glycolysis in contrast to those observed in infection with low-pathogenicity A. baumannii. Perturbation of oxidative phosphorylation, destabilization of mitochondrial ribosomes, and interference with mitochondrial metabolic pathways were identified as important pathogenicity mechanisms. Understanding the interaction of human host cells with the current global A. baumannii clone is the basis to identify novel therapeutic targets. IMPORTANCE Virulence traits of Acinetobacter baumannii isolates of the worldwide most prevalent international clonal lineage, IC2, remain largely unknown. In our study, multidrug-resistant IC2 clinical isolates differed substantially in their virulence potential despite their close genetic relatedness. Our data suggest that, at least for some isolates, mitochondria are important target organelles during infection of primary human endothelial cells. Complexes of the respiratory chain were extensively remodelled after infection with a highly virulent A. baumannii strain, leading to metabolic adaptation characterized by severely reduced respiration and glycolysis. Perturbations of both mitochondrial morphology and mitoribosomes were identified as important pathogenicity mechanisms. Our data might help to further decipher the molecular mechanisms of A. baumannii and host mitochondrial interaction during infection.
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Affiliation(s)
- Laura Leukert
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - Manuela Tietgen
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt am Main, Germany
- University Center of Competence for Infection Control of the State of Hesse, Frankfurt am Main, Germany
| | - Felix F. Krause
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt am Main, Germany
- Institute for Medical Microbiology and Hygiene, Philipps-University, Marburg, Germany
| | - Tilman G. Schultze
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - Dominik C. Fuhrmann
- Institute of Biochemistry I, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany
| | - Charline Debruyne
- Laboratory of Molecular Microbiology and Structural Biochemistry, Centre National de la Recherche Scientifique UMR5086, Université de Lyon, Lyon, France
| | - Suzana P. Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, Centre National de la Recherche Scientifique UMR5086, Université de Lyon, Lyon, France
| | - Alexander Visekruna
- Institute for Medical Microbiology and Hygiene, Philipps-University, Marburg, Germany
| | - llka Wittig
- Functional Proteomics, Institute of Cardiovascular Physiology, Goethe University, Frankfurt am Main, Germany
| | - Stephan Göttig
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt am Main, Germany
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20
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Bai J, Raustad N, Denoncourt J, van Opijnen T, Geisinger E. Genome-wide phage susceptibility analysis in Acinetobacter baumannii reveals capsule modulation strategies that determine phage infectivity. PLoS Pathog 2023; 19:e1010928. [PMID: 37289824 PMCID: PMC10249906 DOI: 10.1371/journal.ppat.1010928] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 04/27/2023] [Indexed: 06/10/2023] Open
Abstract
Phage have gained renewed interest as an adjunctive treatment for life-threatening infections with the resistant nosocomial pathogen Acinetobacter baumannii. Our understanding of how A. baumannii defends against phage remains limited, although this information could lead to improved antimicrobial therapies. To address this problem, we identified genome-wide determinants of phage susceptibility in A. baumannii using Tn-seq. These studies focused on the lytic phage Loki, which targets Acinetobacter by unknown mechanisms. We identified 41 candidate loci that increase susceptibility to Loki when disrupted, and 10 that decrease susceptibility. Combined with spontaneous resistance mapping, our results support the model that Loki uses the K3 capsule as an essential receptor, and that capsule modulation provides A. baumannii with strategies to control vulnerability to phage. A key center of this control is transcriptional regulation of capsule synthesis and phage virulence by the global regulator BfmRS. Mutations hyperactivating BfmRS simultaneously increase capsule levels, Loki adsorption, Loki replication, and host killing, while BfmRS-inactivating mutations have the opposite effect, reducing capsule and blocking Loki infection. We identified novel BfmRS-activating mutations, including knockouts of a T2 RNase protein and the disulfide formation enzyme DsbA, that hypersensitize bacteria to phage challenge. We further found that mutation of a glycosyltransferase known to alter capsule structure and bacterial virulence can also cause complete phage resistance. Finally, additional factors including lipooligosaccharide and Lon protease act independently of capsule modulation to interfere with Loki infection. This work demonstrates that regulatory and structural modulation of capsule, known to alter A. baumannii virulence, is also a major determinant of susceptibility to phage.
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Affiliation(s)
- Jinna Bai
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Nicole Raustad
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Jason Denoncourt
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Tim van Opijnen
- Broad Institute of MIT and Harvard, CISID, Cambridge, Massachusetts, United States of America
| | - Edward Geisinger
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
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21
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Ren X, Palmer LD. Acinetobacter Metabolism in Infection and Antimicrobial Resistance. Infect Immun 2023:e0043322. [PMID: 37191522 DOI: 10.1128/iai.00433-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
Acinetobacter infections have high rates of mortality due to an increasing incidence of infections by multidrug-resistant (MDR) and extensively-drug-resistant (XDR) strains. Therefore, new therapeutic strategies for the treatment of Acinetobacter infections are urgently needed. Acinetobacter spp. are Gram-negative coccobacilli that are obligate aerobes and can utilize a wide variety of carbon sources. Acinetobacter baumannii is the main cause of Acinetobacter infections, and recent work has identified multiple strategies A. baumannii uses to acquire nutrients and replicate in the face of host nutrient restriction. Some host nutrient sources also serve antimicrobial and immunomodulatory functions. Hence, understanding Acinetobacter metabolism during infection may provide new insights into novel infection control measures. In this review, we focus on the role of metabolism during infection and in resistance to antibiotics and other antimicrobial agents and discuss the possibility that metabolism may be exploited to identify novel targets to treat Acinetobacter infections.
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Affiliation(s)
- Xiaomei Ren
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
| | - Lauren D Palmer
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
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22
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Peters DL, Davis CM, Harris G, Zhou H, Rather PN, Hrapovic S, Lam E, Dennis JJ, Chen W. Characterization of Virulent T4-Like Acinetobacter baumannii Bacteriophages DLP1 and DLP2. Viruses 2023; 15:v15030739. [PMID: 36992448 PMCID: PMC10051250 DOI: 10.3390/v15030739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/07/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023] Open
Abstract
The world is currently facing a global health crisis due to the rapid increase in antimicrobial-resistant bacterial infections. One of the most concerning pathogens is Acinetobacter baumannii, which is listed as a Priority 1 pathogen by the World Health Organization. This Gram-negative bacterium has many intrinsic antibiotic resistance mechanisms and the ability to quickly acquire new resistance determinants from its environment. A limited number of effective antibiotics against this pathogen complicates the treatment of A. baumannii infections. A potential treatment option that is rapidly gaining interest is “phage therapy”, or the clinical application of bacteriophages to selectively kill bacteria. The myoviruses DLP1 and DLP2 (vB_AbaM-DLP_1 and vB_AbaM-DLP_2, respectively) were isolated from sewage samples using a capsule minus variant of A. baumannii strain AB5075. Host range analysis of these phages against 107 A. baumannii strains shows a limited host range, infecting 15 and 21 for phages DLP1 and DLP2, respectively. Phage DLP1 has a large burst size of 239 PFU/cell, a latency period of 20 min, and virulence index of 0.93. In contrast, DLP2 has a smaller burst size of 24 PFU/cell, a latency period of 20 min, and virulence index of 0.86. Both phages show potential for use as therapeutics to combat A. baumannii infections.
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Affiliation(s)
- Danielle L. Peters
- Human Health Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
- Correspondence:
| | - Carly M. Davis
- Human Health Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Greg Harris
- Human Health Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Hongyan Zhou
- Human Health Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Philip N. Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
| | - Sabahudin Hrapovic
- Aquatic and Crop Resource Development (ACRD) Research Center, National Research Council Canada, Montreal, QC H4P 2R2, Canada
| | - Edmond Lam
- Aquatic and Crop Resource Development (ACRD) Research Center, National Research Council Canada, Montreal, QC H4P 2R2, Canada
| | - Jonathan J. Dennis
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Wangxue Chen
- Human Health Therapeutics (HHT) Research Center, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
- Department of Biology, Brock University, St. Catharines, ON L2S 3A1, Canada
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23
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Shadan A, Pathak A, Ma Y, Pathania R, Singh RP. Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infection. Front Cell Infect Microbiol 2023; 13:1053968. [PMID: 36968113 PMCID: PMC10038080 DOI: 10.3389/fcimb.2023.1053968] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infectionAcinetobacter baumannii is a gram-negative multidrug-resistant nosocomial pathogen and a major cause of hospital acquired infetions. Carbapenem resistant A. baumannii has been categorised as a Priority1 critial pathogen by the World Health Organisation. A. baumannii is responsible for infections in hospital settings, clinical sectors, ventilator-associated pneumonia, and bloodstream infections with a mortality rates up to 35%. With the development of advanced genome sequencing, molecular mechanisms of manipulating bacterial genomes, and animal infection studies, it has become more convenient to identify the factors that play a major role in A. baumannii infection and its persistence. In the present review, we have explored the mechanism of infection, virulence factors, and various other factors associated with the pathogenesis of this organism. Additionally, the role of the innate and adaptive immune response, and the current progress in the development of innovative strategies to combat this multidrug-resistant pathogen is also discussed.
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Affiliation(s)
- Afreen Shadan
- Department of Microbiology, Dr. Shyama Prasad Mukherjee University, Ranchi, Jharkhand, India
| | - Avik Pathak
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
| | - Ying Ma
- College of Resources and Environment, Southwest University, Chongqing, China
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Ranjana Pathania
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Ranchi, Jharkhand, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
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24
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High-Resolution Bacterial Cytological Profiling Reveals Intrapopulation Morphological Variations upon Antibiotic Exposure. Antimicrob Agents Chemother 2023; 67:e0130722. [PMID: 36625642 PMCID: PMC9933734 DOI: 10.1128/aac.01307-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Phenotypic heterogeneity is crucial to bacterial survival and could provide insights into the mechanism of action (MOA) of antibiotics, especially those with polypharmacological actions. Although phenotypic changes among individual cells could be detected by existing profiling methods, due to the data complexity, only population average data were commonly used, thereby overlooking the heterogeneity. In this study, we developed a high-resolution bacterial cytological profiling method that can capture morphological variations of bacteria upon antibiotic treatment. With an unprecedented single-cell resolution, this method classifies morphological changes of individual cells into known MOAs with an overall accuracy above 90%. We next showed that combinations of two antibiotics induce altered cell morphologies that are either unique or similar to that of an antibiotic in the combinations. With these combinatorial profiles, this method successfully revealed multiple cytological changes caused by a natural product-derived compound that, by itself, is inactive against Acinetobacter baumannii but synergistically exerts its multiple antibacterial activities in the presence of colistin. The findings have paved the way for future single-cell profiling in bacteria and have highlighted previously underappreciated intrapopulation variations caused by antibiotic perturbation.
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25
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Lai SJ, Tu IF, Tseng TS, Tsai YH, Wu SH. The deficiency of poly-β-1,6-N-acetyl-glucosamine deacetylase trigger A. baumannii to convert to biofilm-independent colistin-tolerant cells. Sci Rep 2023; 13:2800. [PMID: 36797306 PMCID: PMC9935895 DOI: 10.1038/s41598-023-30065-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 02/15/2023] [Indexed: 02/18/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen that can be resistant to antibiotics by rapidly modulating its anti-drug mechanisms. The multidrug-resistant A. baumannii has been considered one of the most threatening pathogens to our society. Biofilm formation and persistent cells within the biofilm matrix are recognized as intractable problems, especially in hospital-acquired infections. Poly-β-1,6-N-acetyl-glucosamine (PNAG) is one of the important building blocks in A. baumannii's biofilm. Here, we discover a protein phosphoryl-regulation on PNAG deacetylase, AbPgaB1, in which residue Ser411 was phosphorylated. The phosphoryl-regulation on AbPgaB1 modulates the product turnover rate in which deacetylated PNAG is produced and reflected in biofilm production. We further uncovered the PgaB deficient A. baumannii strain shows the lowest level of biofilm production but has a high minimal inhibition concentration to antibiotic colistin and tetracycline. Based on bactericidal post-antibiotic effects and time-dependent killing assays with antibacterial drugs, we claim that the PgaB-deficient A. baumannii converts to colistin-tolerant cells. This study utilizes a biofilm-independent colistin-tolerant model of A. baumannii to further investigate its characteristics and mechanisms to better understand clinical outcomes.
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Affiliation(s)
- Shu-Jung Lai
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, 404333, Taiwan. .,Research Center for Cancer Biology, China Medical University, Taichung, 404333, Taiwan.
| | - I-Fan Tu
- grid.28665.3f0000 0001 2287 1366Institute of Biological Chemistry, Academia Sinica, Taipei, 11529 Taiwan
| | - Tien-Sheng Tseng
- grid.260542.70000 0004 0532 3749Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Hsuan Tsai
- grid.510951.90000 0004 7775 6738Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132 China
| | - Shih-Hsiung Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan.
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26
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Valcek A, Philippe C, Whiteway C, Robino E, Nesporova K, Bové M, Coenye T, De Pooter T, De Coster W, Strazisar M, Van der Henst C. Phenotypic Characterization and Heterogeneity among Modern Clinical Isolates of Acinetobacter baumannii. Microbiol Spectr 2023; 11:e0306122. [PMID: 36475894 PMCID: PMC9927488 DOI: 10.1128/spectrum.03061-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogenic bacterium prioritized by WHO and CDC because of its increasing antibiotic resistance. Heterogeneity among strains represents the hallmark of A. baumannii bacteria. We wondered to what extent extensively used strains, so-called reference strains, reflect the dynamic nature and intrinsic heterogeneity of these bacteria. We analyzed multiple phenotypic traits of 43 nonredundant, modern, and multidrug-resistant, extensively drug-resistant, and pandrug-resistant clinical isolates and broadly used strains of A. baumannii. Comparison of these isolates at the genetic and phenotypic levels confirmed a high degree of heterogeneity. Importantly, we observed that a significant portion of modern clinical isolates strongly differs from several historically established strains in the light of colony morphology, cellular density, capsule production, natural transformability, and in vivo virulence. The significant differences between modern clinical isolates of A. baumannii and established strains could hamper the study of A. baumannii, especially concerning its virulence and resistance mechanisms. Hence, we propose a variable collection of modern clinical isolates that are characterized at the genetic and phenotypic levels, covering a wide range of the phenotypic spectrum, with six different macrocolony type groups, from avirulent to hypervirulent phenotypes, and with naturally noncapsulated to hypermucoid strains, with intermediate phenotypes as well. Strain-specific mechanistic observations remain interesting per se, and established "reference" strains have undoubtedly been shown to be very useful to study basic mechanisms of A. baumannii biology. However, any study based on a specific strain of A. baumannii should be compared to modern and clinically relevant isolates. IMPORTANCE Acinetobacter baumannii is a bacterium prioritized by the CDC and WHO because of its increasing antibiotic resistance, leading to treatment failures. The hallmark of this pathogen is the high heterogeneity observed among isolates, due to a very dynamic genome. In this context, we tested if a subset of broadly used isolates, considered "reference" strains, was reflecting the genetic and phenotypic diversity found among currently circulating clinical isolates. We observed that the so-called reference strains do not cover the whole diversity of the modern clinical isolates. While formerly established strains successfully generated a strong base of knowledge in the A. baumannii field and beyond, our study shows that a rational choice of strain, related to a specific biological question, should be taken into consideration. Any data obtained with historically established strains should also be compared to modern and clinically relevant isolates, especially concerning drug screening, resistance, and virulence contexts.
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Affiliation(s)
- Adam Valcek
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Chantal Philippe
- Research Unit in the Biology of Microorganisms (URBM), NARILIS, University of Namur (UNamur), Namur, Belgium
| | - Clémence Whiteway
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Etienne Robino
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Kristina Nesporova
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Mona Bové
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Tim De Pooter
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Wouter De Coster
- Applied and Translational Neurogenomics Group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Applied and Translational Neurogenomics Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Mojca Strazisar
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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27
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Zou D, Chang J, Lu S, Xu J, Hu P, Zhang K, Sun X, Guo W, Li Y, Liu Z, Ren H. Analysis of virulence proteins in pathogenic Acinetobacter baumannii to provide early warning of zoonotic risk. Microbiol Res 2023; 266:127222. [DOI: 10.1016/j.micres.2022.127222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/18/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022]
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28
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Ding L, Yang Y, Zheng C, Sun G, Han R, Guo Y, Yin D, Wu S, Zhu D, Hu F. Activities of Eravacycline, Tedizolid, Norvancomycin, Nemonoxacin, Ceftaroline, and Comparators against 1,871 Staphylococcus and 1,068 Enterococcus Species Isolates from China: Updated Report of the CHINET Study 2019. Microbiol Spectr 2022; 10:e0171522. [PMID: 36326536 PMCID: PMC9769667 DOI: 10.1128/spectrum.01715-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022] Open
Abstract
To evaluate the in vitro activities of eravacycline, tedizolid, nemonoxacin, norvancomycin, and ceftaroline against Staphylococcus and Enterococcus species isolates were collected as part of the China Antimicrobial Surveillance Network (CHINET) in 2019 to provide susceptibility data for Staphylococcus spp. and Enterococcus spp. for their future development and application in clinical practice. Antimicrobial susceptibility testing was performed using the CLSI broth microdilution reference method. Eravacycline was highly active against Staphylococcus and Enterococcus species isolates, proved by the MIC50/90: 0.06/0.125, 0.06/0.25, 0.06/0.25, 0.06/0.25, 0.125/0.5, 0.125/0.25, and 0.03/0.06 mg/L for Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), S. epidermidis, S. hominis, S. haemolyticus, Enterococcus faecalis, and E. faecium, respectively. S. aureus isolates tested were fully susceptible to tedizolid. Still, nonsusceptible isolates were found for E. faecalis (72/567 [12.7%]) and E. faecium (12/501 [2.4%]). Norvancomycin at 2 mg/L could inhibit 100% of Staphylococcus spp., while 1 mg/L of ceftaroline could inhibit 78.9% of MRSA and 99.9% of methicillin-susceptible S. aureus (MSSA) isolates. Additionally, nemonoxacin was also active against Staphylococcus and Enterococcus species isolates tested (shown by the following MIC90s and ranges, in milligrams per liter: 2 and ≤0.015 to 8 for MRSA, 0.25 and ≤0.015 to 4 for MSSA, 0.5 and ≤0.015 to 8 for S. epidermidis, and 4 and ≤0.015 to >32 for E. faecalis). In conclusion, both eravacycline and tedizolid were highly active against clinical isolates of Staphylococcus spp. and Enterococcus spp. recently collected across China. Nemonoxacin showed potent activity against Staphylococcus spp. and E. faecalis but limited activity against E. faecium. Norvancomycin and ceftaroline displayed highly potent activity against Staphylococcus spp. IMPORTANCE Antimicrobial resistance has become a severe threat to global public health. According to statistics, nearly 700,000 people die from bacterial infections worldwide (J. O'Neill, Antimicrobial Resistance: Tackling a Crisis for the Health and Wealth of Nations, 2014; C. Y. Chin, K. A. Tipton, M. Farokhyfar, E. M. Burd, et al., Nat Microbiol 3:563-569, 2018, https://doi.org/10.1038/s41564-018-0151-5). The number of bacterial infections is expected to climb to 10 million by 2050, showing that bacterial resistance has become a significant problem that cannot be ignored. It is crucial to develop new antimicrobial agents to combat antimicrobial-resistant bacteria. In this study, we evaluated the in vitro activities of eravacycline, tedizolid, nemonoxacin, norvancomycin, and ceftaroline against Staphylococcus spp. and Enterococcus species isolates which were collected as part of CHINET in 2019. We believe that this study can provide susceptibility data for Staphylococcus spp. and Enterococcus spp. for their future development and application in clinical practice.
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Affiliation(s)
- Li Ding
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Yang Yang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Changhe Zheng
- Yancheng Tinghu District People’s Hospital, Jiangsu, China
| | - Gang Sun
- The First Division Hospital of Xinjiang Corps, Xinjiang, China
| | - Renru Han
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Yan Guo
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Dandan Yin
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Shi Wu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Demei Zhu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Fupin Hu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
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Abstract
The ability of bacteria to respond to changes in their environment is critical to their survival, allowing them to withstand stress, form complex communities, and induce virulence responses during host infection. A remarkable feature of many of these bacterial responses is that they are often variable across individual cells, despite occurring in an isogenic population exposed to a homogeneous environmental change, a phenomenon known as phenotypic heterogeneity. Phenotypic heterogeneity can enable bet-hedging or division of labor strategies that allow bacteria to survive fluctuating conditions. Investigating the significance of phenotypic heterogeneity in environmental transitions requires dynamic, single-cell data. Technical advances in quantitative single-cell measurements, imaging, and microfluidics have led to a surge of publications on this topic. Here, we review recent discoveries on single-cell bacterial responses to environmental transitions of various origins and complexities, from simple diauxic shifts to community behaviors in biofilm formation to virulence regulation during infection. We describe how these studies firmly establish that this form of heterogeneity is prevalent and a conserved mechanism by which bacteria cope with fluctuating conditions. We end with an outline of current challenges and future directions for the field. While it remains challenging to predict how an individual bacterium will respond to a given environmental input, we anticipate that capturing the dynamics of the process will begin to resolve this and facilitate rational perturbation of environmental responses for therapeutic and bioengineering purposes.
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Noel HR, Petrey JR, Palmer LD. Mobile genetic elements in Acinetobacter antibiotic-resistance acquisition and dissemination. Ann N Y Acad Sci 2022; 1518:166-182. [PMID: 36316792 PMCID: PMC9771954 DOI: 10.1111/nyas.14918] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pathogenic Acinetobacter species, most notably Acinetobacter baumannii, are a significant cause of healthcare-associated infections worldwide. Acinetobacter infections are of particular concern to global health due to the high rates of multidrug resistance and extensive drug resistance. Widespread genome sequencing and analysis has determined that bacterial antibiotic resistance is often acquired and disseminated through the movement of mobile genetic elements, including insertion sequences (IS), transposons, integrons, and conjugative plasmids. In Acinetobacter specifically, resistance to carbapenems and cephalosporins is highly correlated with IS, as many ISAba elements encode strong outwardly facing promoters that are required for sufficient expression of β-lactamases to confer clinical resistance. Here, we review the role of mobile genetic elements in antibiotic resistance in Acinetobacter species through the framework of the mechanism of resistance acquisition and with a focus on experimentally validated mechanisms.
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Affiliation(s)
- Hannah R. Noel
- Department of Microbiology and Immunology University of Illinois Chicago Chicago Illinois USA
| | - Jessica R. Petrey
- Department of Microbiology and Immunology University of Illinois Chicago Chicago Illinois USA
| | - Lauren D. Palmer
- Department of Microbiology and Immunology University of Illinois Chicago Chicago Illinois USA
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31
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de Dios R, Proctor CR, Maslova E, Dzalbe S, Rudolph CJ, McCarthy RR. Artificial sweeteners inhibit multidrug-resistant pathogen growth and potentiate antibiotic activity. EMBO Mol Med 2022; 15:e16397. [PMID: 36412260 PMCID: PMC9832836 DOI: 10.15252/emmm.202216397] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 10/28/2022] [Accepted: 10/28/2022] [Indexed: 11/23/2022] Open
Abstract
Antimicrobial resistance is one of the most pressing concerns of our time. The human diet is rich with compounds that alter bacterial gut communities and virulence-associated behaviours, suggesting food additives may be a niche for the discovery of novel anti-virulence compounds. Here, we identify three artificial sweeteners, saccharin, cyclamate and acesulfame-K (ace-K), that have a major growth inhibitory effect on priority pathogens. We further characterise the impact of ace-K on multidrug-resistant Acinetobacter baumannii, demonstrating that it can disable virulence behaviours such as biofilm formation, motility and the ability to acquire exogenous antibiotic-resistant genes. Further analysis revealed the mechanism of growth inhibition is through bulge-mediated cell lysis and that cells can be rescued by cation supplementation. Antibiotic sensitivity assays demonstrated that at sub-lethal concentrations, ace-K can resensitise A. baumannii to last resort antibiotics, including carbapenems. Using a novel ex vivo porcine skin wound model, we show that ace-K antimicrobial activity is maintained in the wound microenvironment. Our findings demonstrate the influence of artificial sweeteners on pathogen behaviour and uncover their therapeutic potential.
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Affiliation(s)
- Rubén de Dios
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Chris R Proctor
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Evgenia Maslova
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Sindija Dzalbe
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Christian J Rudolph
- Division of Biosciences, Department of Life Sciences, Centre for Genome Engineering and Maintenance, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
| | - Ronan R McCarthy
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health, Medicine and Life SciencesBrunel University LondonUxbridgeUK
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Pérez-Varela M, Tierney ARP, Dawson E, Hutcheson AR, Tipton KA, Anderson SE, Haldopoulos ME, Song S, Tomlinson BR, Shaw LN, Weiss DS, Kim M, Rather PN. Stochastic activation of a family of TetR type transcriptional regulators controls phenotypic heterogeneity in Acinetobacter baumannii. PNAS NEXUS 2022; 1:pgac231. [PMID: 36704122 PMCID: PMC9802203 DOI: 10.1093/pnasnexus/pgac231] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 10/06/2022] [Indexed: 11/13/2022]
Abstract
Phenotypic heterogeneity is an important mechanism for regulating bacterial virulence, where a single regulatory switch is typically activated to generate virulent and avirulent subpopulations. The opportunistic pathogen Acinetobacter baumannii can transition at high frequency between virulent opaque (VIR-O) and avirulent translucent subpopulations, distinguished by cells that form opaque or translucent colonies. We demonstrate that expression of 11 TetR-type transcriptional regulators (TTTRs) can drive cells from the VIR-O opaque subpopulation to cells that form translucent colonies. Remarkably, in a subpopulation of VIR-O cells, four of these TTTRs were stochastically activated in different combinations to drive cells to the translucent state. The resulting translucent subvariants exhibited unique phenotypic differences and the majority were avirulent. Due to their functional redundancy, a quadruple mutant with all four of these TTTRs inactivated was required to observe a loss of switching from the VIR-O state. Further, we demonstrate a small RNA, SrvS, acts as a "rheostat," where the levels of SrvS expression influences both the VIR-O to translucent switching frequency, and which TTTR is activated when VIR-O cells switch. In summary, this work has revealed a new paradigm for phenotypic switching in bacteria, where an unprecedented number of related transcriptional regulators are activated in different combinations to control virulence and generate unique translucent subvariants with distinct phenotypic properties.
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Affiliation(s)
- María Pérez-Varela
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
| | - Aimee R P Tierney
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
| | - Emma Dawson
- Department of Physics, Emory University, Atlanta, GA 30322, USA
| | - Anna R Hutcheson
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
| | - Kyle A Tipton
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
| | - Sarah E Anderson
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
| | - Marina E Haldopoulos
- Emory Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
- Emory Vaccine Center, Emory University, Atlanta, GA 30322, USA
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Shaina Song
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
| | - Brooke R Tomlinson
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - Lindsey N Shaw
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - David S Weiss
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
- Emory Vaccine Center, Emory University, Atlanta, GA 30322, USA
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Minsu Kim
- Department of Physics, Emory University, Atlanta, GA 30322, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
| | - Philip N Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30322, USA
- Research Service, Atlanta VA Medical Center, Decatur, GA 30033, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, GA 30322, USA
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33
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de Dios R, Gadar K, McCarthy RR. A high-efficiency scar-free genome-editing toolkit for Acinetobacter baumannii. J Antimicrob Chemother 2022; 77:3390-3398. [PMID: 36216579 PMCID: PMC9704439 DOI: 10.1093/jac/dkac328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 09/05/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The current mutagenesis tools for Acinetobacter baumannii leave selection markers or residual sequences behind, or involve tedious counterselection and screening steps. Furthermore, they are usually adapted for model strains, rather than for MDR clinical isolates. OBJECTIVES To develop a scar-free genome-editing tool suitable for chromosomal and plasmid modifications in MDR A. baumannii AB5075. METHODS We prove the efficiency of our adapted genome-editing system by deleting the multidrug efflux pumps craA, cmlA5 and resistance island 2 (RI2), as well as curing plasmid p1AB5075, and combining these mutations. We then characterized the susceptibility of the mutants compared with the WT to different antibiotics (i.e. chloramphenicol, amikacin and tobramycin) by disc diffusion assays and determined the MIC for each strain. RESULTS We successfully adapted the genome-editing protocol to A. baumannii AB5075, achieving a double recombination frequency close to 100% and routinely securing the construction of a mutant within 10 working days. Furthermore, we show that both CraA and p1AB5075 are involved in chloramphenicol resistance, and that RI2 and p1AB5075 play a role in resistance to amikacin and tobramycin. CONCLUSIONS We have developed a versatile and highly efficient genome-editing tool for A. baumannii. We have demonstrated it can be used to modify both the chromosome and native plasmids. By challenging the method, we show the role of CraA and p1AB5075 in antibiotic resistance.
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Affiliation(s)
- Rubén de Dios
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
| | - Kavita Gadar
- Division of Biosciences, Department of Life Sciences, Centre of Inflammation Research and Translational Medicine, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK
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Ahsan U, Mushtaq F, Saleem S, Malik A, Sarfaraz H, Shahzad M, Uhlin BE, Ahmad I. Emergence of high colistin resistance in carbapenem resistant Acinetobacter baumannii in Pakistan and its potential management through immunomodulatory effect of an extract from Saussurea lappa. Front Pharmacol 2022; 13:986802. [PMID: 36188613 PMCID: PMC9523213 DOI: 10.3389/fphar.2022.986802] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 08/17/2022] [Indexed: 11/24/2022] Open
Abstract
Carbapenem resistant Acinetobacter baumannii has emerged as one of the most difficult to treat nosocomial bacterial infections in recent years. It was one of the major causes of secondary infections in Covid-19 patients in developing countries. The polycationic polypeptide antibiotic colistin is used as a last resort drug to treat carbapenem resistant A. baumannii infections. Therefore, resistance to colistin is considered as a serious medical threat. The purpose of this study was to assess the current status of colistin resistance in Pakistan, a country where carbapenem resistant A. bumannii infections are endemic, to understand the impact of colistin resistance on virulence in mice and to assess alternative strategies to treat such infections. Out of 150 isolates collected from five hospitals in Pakistan during 2019–20, 84% were carbapenem resistant and 7.3% were additionally resistant to colistin. There were two isolates resistant to all tested antibiotics and 83% of colistin resistant isolates were susceptible to only tetracycline family drugs doxycycline and minocycline. Doxycycline exhibited a synergetic bactericidal effect with colistin even in colistin resistant isolates. Exposure of A. baumannii 17978 to sub inhibitory concentrations of colistin identified novel point mutations associated with colistin resistance. Colistin tolerance acquired independent of mutations in lpxA, lpxB, lpxC, lpxD, and pmrAB supressed the proinflammatory immune response in epithelial cells and the virulence in a mouse infection model. Moreover, the oral administration of water extract of Saussuria lappa, although not showing antimicrobial activity against A. baumannii in vitro, lowered the number of colonizing bacteria in liver, spleen and lung of the mouse model and also lowered the levels of neutrophils and interleukin 8 in mice. Our findings suggest that the S. lappa extract exhibits an immunomodulatory effect with potential to reduce and cure systemic infections by both opaque and translucent colony variants of A. baumannii.
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Affiliation(s)
- Umaira Ahsan
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
- Department of Microbiology, University of Health Sciences, Lahore, Pakistan
| | - Fizza Mushtaq
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Sidrah Saleem
- Department of Microbiology, University of Health Sciences, Lahore, Pakistan
| | - Abdul Malik
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Hira Sarfaraz
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Muhammad Shahzad
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
| | - Bernt Eric Uhlin
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Irfan Ahmad
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- *Correspondence: Irfan Ahmad, ,
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Tian C, Xing M, Fu L, Zhao Y, Fan X, Wang S. Emergence of uncommon KL38-OCL6-ST220 carbapenem-resistant Acinetobacter pittii strain, co-producing chromosomal NDM-1 and OXA-820 carbapenemases. Front Cell Infect Microbiol 2022; 12:943735. [PMID: 36034705 PMCID: PMC9411868 DOI: 10.3389/fcimb.2022.943735] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 07/12/2022] [Indexed: 11/23/2022] Open
Abstract
Objective To characterize one KL38-OCL6-ST220 carbapenem-resistant Acinetobacter pittii strain, co-producing chromosomal NDM-1 and OXA-820 carbapenemases. Methods A. pittii TCM strain was isolated from a bloodstream infection (BSI). Antimicrobial susceptibility tests were conducted via disc diffusion and broth microdilution. Stability experiments of blaNDM-1 and blaOXA-820 carbapenemase genes were further performed. Whole-genome sequencing (WGS) was performed on the Illumina and Oxford Nanopore platforms. Multilocus sequence typing (MLST) was analyzed based on the Pasteur and Oxford schemes. Resistance genes, virulence factors, and insertion sequences (ISs) were identified with ABRicate based on ResFinder 4.0, virulence factor database (VFDB), and ISfinder. Capsular polysaccharide (KL), lipooligosaccharide outer core (OCL), and plasmid reconstruction were tested using Kaptive and PLACNETw. PHASTER was used to predict prophage regions. A comparative genomics analysis of all ST220 A. pittii strains from the public database was carried out. Point mutations, average nucleotide identity (ANI), DNA–DNA hybridization (DDH) distances, and pan-genome analysis were performed. Results A. pittii TCM was ST220Pas and ST1818Oxf with KL38 and OCL6, respectively. It was resistant to imipenem, meropenem, and ciprofloxacin but still susceptible to amikacin, colistin, and tigecycline. WGS revealed that A. pittii TCM contained one circular chromosome and four plasmids. The Tn125 composite transposon, including blaNDM-1, was located in the chromosome with 3-bp target site duplications (TSDs). Many virulence factors and the blaOXA-820 carbapenemase gene were also identified. The stability assays revealed that blaNDM-1 and blaOXA-820 were stabilized by passage in an antibiotic-free medium. Moreover, 12 prophage regions were identified in the chromosome. Phylogenetic analysis showed that there are 11 ST220 A. pittii strains, and one collected from Anhui, China was closely related. All ST220 A. pittii strains presented high ANI and DDH values; they ranged from 99.85% to 100% for ANI and from 97.4% to 99.9% for DDH. Pan-genome analysis revealed 3,200 core genes, 0 soft core genes, 1,571 shell genes, and 933 cloud genes among the 11 ST220 A. pittii strains. Conclusions The coexistence of chromosomal NDM-1 and OXA-820 carbapenemases in A. pittii presents a huge challenge in healthcare settings. Increased surveillance of this species in hospital and community settings is urgently needed.
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Affiliation(s)
- Chongmei Tian
- Department of Pharmacy, Shaoxing Hospital of Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medical University, Shaoxing, China
| | - Mengyu Xing
- Department of Pharmacy, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Liping Fu
- Department of Pharmacy, Shaoxing Hospital of Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medical University, Shaoxing, China
| | - Yaping Zhao
- Department of Pharmacy, Shaoxing Hospital of Traditional Chinese Medicine Affiliated to Zhejiang Chinese Medical University, Shaoxing, China
| | - Xueyu Fan
- Department of Clinical Laboratory, Quzhou People’s Hospital, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou, China
| | - Siwei Wang
- Core Facility, Quzhou People’s Hospital, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou, China
- *Correspondence: Siwei Wang,
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Tan YC, Lahiri C. Promising Acinetobacter baumannii Vaccine Candidates and Drug Targets in Recent Years. Front Immunol 2022; 13:900509. [PMID: 35720310 PMCID: PMC9204607 DOI: 10.3389/fimmu.2022.900509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 04/26/2022] [Indexed: 12/14/2022] Open
Abstract
In parallel to the uncontrolled use of antibiotics, the emergence of multidrug-resistant bacteria, like Acinetobacter baumannii, has posed a severe threat. A. baumannii predominates in the nosocomial setting due to its ability to persist in hospitals and survive antibiotic treatment, thereby eventually leading to an increasing prevalence and mortality due to its infection. With the increasing spectra of drug resistance and the incessant collapse of newly discovered antibiotics, new therapeutic countermeasures have been in high demand. Hence, recent research has shown favouritism towards the long-term solution of designing vaccines. Therefore, being a realistic alternative strategy to combat this pathogen, anti-A. Baumannii vaccines research has continued unearthing various antigens with variable results over the last decade. Again, other approaches, including pan-genomics, subtractive proteomics, and reverse vaccination strategies, have shown promise for identifying promiscuous core vaccine candidates that resulted in chimeric vaccine constructs. In addition, the integration of basic knowledge of the pathobiology of this drug-resistant bacteria has also facilitated the development of effective multiantigen vaccines. As opposed to the conventional trial-and-error approach, incorporating the in silico methods in recent studies, particularly network analysis, has manifested a great promise in unearthing novel vaccine candidates from the A. baumannii proteome. Some studies have used multiple A. baumannii data sources to build the co-functional networks and analyze them by k-shell decomposition. Additionally, Whole Genomic Protein Interactome (GPIN) analysis has utilized a rational approach for identifying essential proteins and presenting them as vaccines effective enough to combat the deadly pathogenic threats posed by A. baumannii. Others have identified multiple immune nodes using network-based centrality measurements for synergistic antigen combinations for different vaccination strategies. Protein-protein interactions have also been inferenced utilizing structural approaches, such as molecular docking and molecular dynamics simulation. Similar workflows and technologies were employed to unveil novel A. baumannii drug targets, with a similar trend in the increasing influx of in silico techniques. This review integrates the latest knowledge on the development of A. baumannii vaccines while highlighting the in silico methods as the future of such exploratory research. In parallel, we also briefly summarize recent advancements in A. baumannii drug target research.
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Affiliation(s)
- Yong Chiang Tan
- School of Postgraduate Studies, International Medical University, Kuala Lumpur, Malaysia
| | - Chandrajit Lahiri
- Department of Biological Sciences, Sunway University, Petaling Jaya, Malaysia
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Guo L, Wang L, Zhao Q, Ye L, Ye K, Ma Y, Shen D, Yang J. Genomic Analysis of KPC-2-Producing Klebsiella pneumoniae ST11 Isolates at the Respiratory Department of a Tertiary Care Hospital in Beijing, China. Front Microbiol 2022; 13:929826. [PMID: 35783384 PMCID: PMC9244631 DOI: 10.3389/fmicb.2022.929826] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 05/23/2022] [Indexed: 11/24/2022] Open
Abstract
Background Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an important pathogen causing hospital-associated outbreaks worldwide. The spread of K. pneumoniae carbapenemase-2 (KPC-2)-producing CRKP is primarily associated with sequence type (ST) 11. Methods A total of 152 KPC-2-producing K. pneumoniae ST11 isolates were collected from the respiratory department of a tertiary care hospital in Beijing, China between 2009 and 2018. The genome sequencing of these isolates was performed on the HiSeq X Ten sequencer. Multilocus sequence typing (MLST), capsular type, plasmid replicon types and resistance genes were identified. Fifteen isolates were selected for the subsequent single-molecule real-time (SMRT) sequencing on the PacBio RS II. Alignment of the complete sequences of the plasmids carrying blaKPC–2 and/or virulence genes was performed by using BRIG and Easyfig. Results From 2012 to 2018, the detection rate of the blaKPC–2-carrying CRKP rose rapidly from 3.3 to 28.1%. KPC-2-producing K. pneumoniae ST11 isolates were dominant in CRKP, which emerged in 2012 and caused several outbreaks. Most isolates exhibited multidrug-resistant to commonly used antibiotics, while all the isolates remained susceptible to tigecycline and polymyxin B. The single nucleotide polymorphism (SNP) analysis showed that all these 152 KPC-2-producing K. pneumoniae ST11 isolates could be divided into three genetically distinct clades (A, B, and C) and eleven subclades (A1–A9 and B1–B2). The majority belonged to clade A with KL47 serotype (n = 117, 77.0%), while KL64 and KL16 were identified in clades B and C, respectively. The blaKPC–2-carrying plasmids exhibited diverse types, namely, IncFII (pHN7A8)/IncR(6/15), IncFII (pHN7A8)/IncpA1763–KPC (5/15), IncFII (pHN7A8) (1/15), IncR (1/15), and IncpA1763–KPC (1/15). The genetic environment of blaKPC–2 showed nine IS26-based composite transposons, which had a basic core structure ISKpn27-blaKPC–2-ΔISKpn6. About 27.6% (42/152) isolates co-carried 2 to 4 virulence marker genes (namely, peg344, iucA, iroB, rmpA, and rmpA2) for hvKp strains. At least three isolates were identified to harbor virulence gene-carrying plasmids. Conclusion KPC-2-producing K. pneumoniae ST11 was highly heterogeneous in our hospital. Transmission of these strains was mainly mediated by twelve high-risk clones. The blaKPC–2-carrying plasmids and genetic environment of blaKPC–2 genes exhibited active evolution in K. pneumoniae ST11. More attention should be paid to the tendency of KPC-2-ST11 to acquire hypervirulent plasmids.
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Hubeny J, Korzeniewska E, Buta-Hubeny M, Zieliński W, Rolbiecki D, Harnisz M. Characterization of carbapenem resistance in environmental samples and Acinetobacter spp. isolates from wastewater and river water in Poland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 822:153437. [PMID: 35122847 DOI: 10.1016/j.scitotenv.2022.153437] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 01/21/2022] [Accepted: 01/22/2022] [Indexed: 05/29/2023]
Abstract
The aim of this study was to analyze the prevalence of carbapenem resistance genes in Acinetobacter spp. isolated from wastewater in a municipal WWTP and to determine their spread from treated wastewater to river water with the use of conventional and molecular microbiology methods (qualitative and quantitative PCR and metagenomic analysis). Samples of untreated and treated wastewater and samples of river water obtained upstream and downstream from the wastewater discharge point were collected in 3 seasons (February, June, and September) of 2019. Acinetobacter spp. isolates were obtained by the culture method on the CHROMagar™ Acinetobacter medium. Additionally, environmental DNA was extracted from the samples for metagenomic and qPCR analyses. The presence of beta-lactam resistance genes (Ambler class B and D), insertion sequence ISAba1, and class I, II, and III integron-integrase genes was determined, and the bacterial taxonomic structure and wastewater and river samples was analyzed. Out of the 301 isolates obtained on the CHROMagar™ Acinetobacter medium, 258 belonged to the genus Acinetobacter, including 21 isolates that were identified as Acinetobacter baumannii. The highest number of Acinetobacter spp. and A. baumannii isolates were obtained from wastewater and river water samples collected in June and September. The ISAba1/blaOXA-51 complex was identified in 13 isolates, which confirms the occurrence of carbapenem-resistance isolates in the analyzed samples. The number of Acinetobacter isolates carrying antibiotic resistance genes (ARGs) increased in river water samples collected downstream from the wastewater discharge point (48 out of 258 isolates - 18.6%) compared to river water samples collected upstream from the wastewater discharge point (34 out of 258 isolates - 13.2%), which suggests that WWTP is a source of pollution in the natural environment. The conducted research provides evidence that bacteria of the genus Acinetobacter may spread alarming beta-lactam resistance in the environment and, therefore, pose a serious epidemiological threat.
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Affiliation(s)
- Jakub Hubeny
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland
| | - Ewa Korzeniewska
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland
| | - Martyna Buta-Hubeny
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland
| | - Wiktor Zieliński
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland
| | - Damian Rolbiecki
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland
| | - Monika Harnisz
- Department of Water Protection Engineering and Environmental Microbiology, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1, 10-720 Olsztyn, Poland.
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Whiteway C, Valcek A, Philippe C, Strazisar M, De Pooter T, Mateus I, Breine A, Van der Henst C. Scarless excision of an insertion sequence restores capsule production and virulence in Acinetobacter baumannii. THE ISME JOURNAL 2022; 16:1473-1477. [PMID: 34949784 PMCID: PMC9038732 DOI: 10.1038/s41396-021-01179-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/07/2021] [Accepted: 12/16/2021] [Indexed: 11/12/2022]
Abstract
We identify a new mechanism mediating capsule production and virulence in the WHO and CDC priority ESKAPE pathogen Acinetobacter baumannii. Non-capsulated and avirulent bacteria can revert into a capsulated and virulent state upon scarless excision of an ISAba13 insertion sequence under stress conditions. Reversion events fully restore capsule production and in vivo virulence. This increases our knowledge about A. baumannii genome dynamics, and the regulation of capsule production, virulence and resistance.
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Affiliation(s)
- Clémence Whiteway
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Adam Valcek
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Chantal Philippe
- Research Unit in the Biology of Microorganisms (URBM), NARILIS, University of Namur (UNamur), Namur, Belgium
| | - Mojca Strazisar
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Tim De Pooter
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Ivan Mateus
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Anke Breine
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium. .,Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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Bray AS, Smith RD, Hudson AW, Hernandez GE, Young TM, George HE, Ernst RK, Zafar MA. MgrB-Dependent Colistin Resistance in Klebsiella pneumoniae Is Associated with an Increase in Host-to-Host Transmission. mBio 2022; 13:e0359521. [PMID: 35311534 PMCID: PMC9040857 DOI: 10.1128/mbio.03595-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022] Open
Abstract
Due to its high transmissibility, Klebsiella pneumoniae is one of the leading causes of nosocomial infections. Here, we studied the biological cost of colistin resistance, an antibiotic of last resort, in this opportunistic pathogen using a murine model of gut colonization and transmission. Colistin resistance in K. pneumoniae is commonly the result of the inactivation of the small regulatory protein MgrB. Without a functional MgrB, the two-component system PhoPQ is constitutively active, leading to an increase in lipid A modifications and subsequent colistin resistance. Using an isogenic mgrB deletion mutant (MgrB-), we demonstrate that the mutant's colistin resistance is not associated with a fitness defect under in vitro growth conditions. However, in our murine model of K. pneumoniae gastrointestinal (GI) colonization, the MgrB- colonizes the gut poorly, allowing us to identify a fitness cost. Moreover, the MgrB- mutant has higher survival outside the host compared with the parental strain. We attribute this enhanced survivability to dysregulation of the PhoPQ two-component system and accumulation of the master stress regulator RpoS. The enhanced survival of MgrB- may be critical for its rapid host-to-host transmission observed in our model. Together, our data using multiple clinical isolates demonstrate that MgrB-dependent colistin resistance in K. pneumoniae comes with a biological cost in gut colonization. However, this cost is mitigated by enhanced survival outside the host and consequently increases its host-to-host transmission. Additionally, it underscores the importance of considering the entire life cycle of a pathogen to determine the actual biological cost associated with antibiotic resistance. IMPORTANCE The biological cost associated with colistin resistance in Klebsiella pneumoniae was examined using a murine model of K. pneumoniae gut colonization and fecal-oral transmission. A common mutation resulting in colistin resistance in K. pneumoniae is a loss-of-function mutation of the small regulatory protein MgrB that regulates the two-component system PhoPQ. Even though colistin resistance in K. pneumoniae comes with a fitness defect in gut colonization, it increases bacterial survival outside the host enabling it to transmit more effectively to a new host. The enhanced survival is dependent upon the accumulation of RpoS and dysregulation of the PhoPQ. Hence, our study expands our understanding of the underlying molecular mechanism contributing to the transmission of colistin-resistant K. pneumoniae.
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Affiliation(s)
- Andrew S. Bray
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Richard D. Smith
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
- Department of Pathology, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - Andrew W. Hudson
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Giovanna E. Hernandez
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Taylor M. Young
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | | | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - M. Ammar Zafar
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
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Bacterial hydrophilins promote pathogen desiccation tolerance. Cell Host Microbe 2022; 30:975-987.e7. [PMID: 35413266 DOI: 10.1016/j.chom.2022.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/14/2022] [Accepted: 03/17/2022] [Indexed: 11/21/2022]
Abstract
Acinetobacter baumannii is a leading cause of hospital-acquired infections, where outbreaks are driven by its ability to persist on surfaces in a desiccated state. Here, we show that A. baumannii causes more virulent pneumonia following desiccation and profile the genetic requirements for desiccation. We find that desiccation tolerance is enhanced upon the disruption of Lon protease, which targets unfolded and aggregated proteins for degradation. Notably, two bacterial hydrophilins, DtpA and DtpB, are transcriptionally upregulated in Δlon via the two-component regulator, BfmR. These proteins, both hydrophilic and intrinsically disordered, promote desiccation tolerance in A. baumannii. Additionally, recombinant DtpA protects purified enzymes from inactivation and improves the desiccation tolerance of a probiotic bacterium when heterologously expressed. These results demonstrate a connection between environmental persistence and pathogenicity in A. baumannii, provide insight into the mechanisms of extreme desiccation tolerance, and reveal potential applications for bacterial hydrophilins in the preservation of protein- and live bacteria-based pharmaceuticals.
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Akoolo L, Pires S, Kim J, Parker D. The Capsule of Acinetobacter baumannii Protects against the Innate Immune Response. J Innate Immun 2022; 14:543-554. [PMID: 35320810 PMCID: PMC9485954 DOI: 10.1159/000522232] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 01/24/2022] [Indexed: 11/19/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen that has recently emerged as a global threat associated with high morbidity, mortality, and antibiotic resistance. We determined the role of type I interferon (IFN) signaling in A. baumannii infection. We report that A. baumannii can induce a type I IFN response that is dependent upon TLR4-TRIF-IRF3 and phagocytosis of the bacterium. Phase variants of A. baumannii that have a reduced capsule, lead to enhanced TLR4-dependent type I IFN induction. This was also observed in a capsule-deficient strain. However, we did not observe a role for this pathway in vivo. The enhanced signaling could be accounted for by increased phagocytosis in capsule-deficient strains that also lead to enhanced host cell-mediated killing. The increased cytokine response in the absence of the capsule was not exclusive to type I IFN signaling. Several cytokines, including the proinflammatory IL-6, were increased in cells stimulated with the capsule-deficient strain, also observed in vivo. After 4 h in our acute pneumonia model, the burden of a capsule-null strain was significantly reduced, yet we observed increases in innate immune cells and inflammatory markers compared to wild-type A. baumannii. This study underscores the role of phase variation in the modulation of host immune responses and indicates that the capsule of A. baumannii plays an important role in protection against host cell killing and evasion from activation of the innate immune response.
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Affiliation(s)
- Lavoisier Akoolo
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Silvia Pires
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Jisun Kim
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Dane Parker
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
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CsrA-Controlled Proteins Reveal New Dimensions of Acinetobacter baumannii Desiccation Tolerance. J Bacteriol 2022; 204:e0047921. [PMID: 35285725 DOI: 10.1128/jb.00479-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hospital environments are excellent reservoirs for the opportunistic pathogen Acinetobacter baumannii in part because it is exceptionally tolerant to desiccation. We found that relative to other A. baumannii strains, the virulent strain AB5075 was strikingly desiccation resistant at 2% relative humidity (RH), suggesting that it is a good model for studies of the functional basis of this trait. Consistent with results from other A. baumannii strains at 40% RH, we found the global posttranscriptional regulator CsrA to be critically important for desiccation tolerance of AB5075 at 2% RH. Proteomics experiments identified proteins that were differentially present in wild-type and csrA mutant cells. Subsequent analysis of mutants in genes encoding some of these proteins revealed six genes that were required for wild-type levels of desiccation tolerance. These include genes for catalase, a universal stress protein, a hypothetical protein, and a biofilm-associated protein. Two genes of unknown function had very strong desiccation phenotypes, with one of the two genes predicting an intrinsically disordered protein (IDP) that binds to DNA. Intrinsically disordered proteins are widespread in eukaryotes but less so in prokaryotes. Our results suggest there are new mechanisms underlying desiccation tolerance in bacteria and identify several key functions involved. IMPORTANCE Acinetobacter baumannii is found in terrestrial environments but can cause nosocomial infections in very sick patients. A factor that contributes to the prevalence of A. baumannii in hospital settings is that it is intrinsically resistant to dry conditions. Here, we established the virulent strain A. baumannii AB5075 as a model for studies of desiccation tolerance at very low relative humidity. Our results show that this trait depends on two proteins of unknown function, one of which is predicted to be an intrinsically disordered protein. This category of protein is critical for the small animals named tardigrades to survive desiccation. Our results suggest that A. baumannii may have novel strategies to survive desiccation that have not previously been seen in bacteria.
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Abstract
Small molecule adjuvants that enhance the activity of established antibiotics represent promising agents in the battle against antibiotic resistance. Adjuvants generally act by inhibiting antibiotic resistance processes, and specifying the process acted on is a critical step in defining an adjuvant's mechanism of action. This step is typically carried out biochemically by identifying molecules that bind adjuvants and then inferring their roles in resistance. Here, we present a complementary genetic strategy based on identifying mutations that both sensitize cells to antibiotic and make them "adjuvant blind." We tested the approach in Acinetobacter baumannii AB5075 using two adjuvants: a well-characterized β-lactamase inhibitor (avibactam) and a compound enhancing outer membrane permeability (aryl 2-aminoimidazole AI-1). The avibactam studies showed that the adjuvant potentiated one β-lactam (ceftazidime) through action on a single β-lactamase (GES-14) and a second (meropenem) by targeting two different enzymes (GES-14 and OXA-23). Mutations impairing disulfide bond formation (DsbAB) also reduced potentiation, possibly by impairing β-lactamase folding. Mutations reducing AI-1 potentiation of canonical Gram-positive antibiotics (vancomycin and clarithromycin) blocked lipooligosaccharide (LOS/LPS) synthesis or its acyl modification. The results indicate that LOS-mediated outer membrane impermeability is targeted by the adjuvant and show the importance of acylation in the resistance. As part of the study, we employed Acinetobacter baylyi as a model to verify the generality of the A. baumannii results and identified the principal resistance genes for ceftazidime, meropenem, vancomycin, and clarithromycin in A. baumannii AB5075. Overall, the work provides a foundation for analyzing adjuvant action using a comprehensive genetic approach. IMPORTANCE One strategy to confront the antibiotic resistance crisis is through the development of adjuvant compounds that increase the efficacy of established drugs. A key step in the development of a natural product adjuvant as a drug is identifying the resistance process it undermines to enhance antibiotic activity. Previous procedures designed to accomplish this have relied on biochemical identification of cell components that bind adjuvant. Here, we present a complementary strategy based on identifying mutations that eliminate adjuvant activity.
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Breine A, Van Gysel M, Elsocht M, Whiteway C, Philippe C, Quinet T, Valcek A, Wouters J, Ballet S, Van der Henst C. Antimicrobial Activity of a Repurposed Harmine-Derived Compound on Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates. Front Cell Infect Microbiol 2022; 11:789672. [PMID: 35141168 PMCID: PMC8819726 DOI: 10.3389/fcimb.2021.789672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/15/2021] [Indexed: 11/18/2022] Open
Abstract
Objectives The spread of antibiotic resistant bacteria is an important threat for human health. Acinetobacter baumannii bacteria impose such a major issue, as multidrug- to pandrug-resistant strains have been isolated, rendering some infections untreatable. In this context, carbapenem-resistant A. baumannii bacteria were ranked as top priority by both WHO and CDC. In addition, A. baumannii bacteria survive in harsh environments, being capable of resisting to disinfectants and to persist prolonged periods of desiccation. Due to the high degree of variability found in A. baumannii isolates, the search for new antibacterials is very challenging because of the requirement of drug target conservation amongst the different strains. Here, we screened a chemical library to identify compounds active against several reference strains and carbapenem-resistant A. baumannii bacteria. Methods A repurposing drug screen was undertaken to identify A. baumannii growth inhibitors. One hit was further characterized by determining the IC50 and testing the activity on 43 modern clinical A. baumannii isolates, amongst which 40 are carbapenem-resistant. Results The repurposing screen led to the identification of a harmine-derived compound, called HDC1, which proves to have bactericidal activity on the multidrug-resistant AB5075-VUB reference strain with an IC50 of 48.23 µM. In addition, HDC1 impairs growth of 43 clinical A. baumannii isolates. Conclusions We identified a compound with inhibitory activity on all tested strains, including carbapenem-resistant clinical A. baumannii isolates.
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Affiliation(s)
- Anke Breine
- Microbial Resistance and Drug Discovery, Vlaams Instituut voor Biotechnologie-Vrije Universiteit Brussel (VIB-VUB) Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Mégane Van Gysel
- Namur Medicine and Drug Innovation Center (NAMEDIC), University of Namur (UNamur), Namur, Belgium
| | - Mathias Elsocht
- Research Group of Organic Chemistry, Departments of Chemistry and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Clémence Whiteway
- Microbial Resistance and Drug Discovery, Vlaams Instituut voor Biotechnologie-Vrije Universiteit Brussel (VIB-VUB) Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Chantal Philippe
- Research Unit in the Biology of Microorganisms (URBM), NARILIS, University of Namur (UNamur), Namur, Belgium
| | - Théo Quinet
- Laboratory of Evolutionary Genetics and Ecology, URBE, University of Namur (UNamur), Namur, Belgium
- Molecular Biology and Evolution, Universite´ Libre de Bruxelles (ULB), Brussels, Belgium
| | - Adam Valcek
- Microbial Resistance and Drug Discovery, Vlaams Instituut voor Biotechnologie-Vrije Universiteit Brussel (VIB-VUB) Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Johan Wouters
- Namur Medicine and Drug Innovation Center (NAMEDIC), University of Namur (UNamur), Namur, Belgium
| | - Steven Ballet
- Research Group of Organic Chemistry, Departments of Chemistry and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, Vlaams Instituut voor Biotechnologie-Vrije Universiteit Brussel (VIB-VUB) Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), Flanders Institute for Biotechnology, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- *Correspondence: Charles Van der Henst,
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Fonseca ÉL, Vicente AC. Integron Functionality and Genome Innovation: An Update on the Subtle and Smart Strategy of Integrase and Gene Cassette Expression Regulation. Microorganisms 2022; 10:microorganisms10020224. [PMID: 35208680 PMCID: PMC8876359 DOI: 10.3390/microorganisms10020224] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 12/22/2022] Open
Abstract
Integrons are considered hot spots for bacterial evolution, since these platforms allow one-step genomic innovation by capturing and expressing genes that provide advantageous novelties, such as antibiotic resistance. The acquisition and shuffling of gene cassettes featured by integrons enable the population to rapidly respond to changing selective pressures. However, in order to avoid deleterious effects and fitness burden, the integron activity must be tightly controlled, which happens in an elegant and elaborate fashion, as discussed in detail in the present review. Here, we aimed to provide an up-to-date overview of the complex regulatory networks that permeate the expression and functionality of integrons at both transcriptional and translational levels. It was possible to compile strong shreds of evidence clearly proving that these versatile platforms include functions other than acquiring and expressing gene cassettes. The well-balanced mechanism of integron expression is intricately related with environmental signals, host cell physiology, fitness, and survival, ultimately leading to adaptation on the demand.
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Trzilova D, Warren MAH, Gadda NC, Williams CL, Tamayo R. Flagellum and toxin phase variation impacts intestinal colonization and disease development in a mouse model of Clostridioides difficile infection. Gut Microbes 2022; 14:2038854. [PMID: 35192433 PMCID: PMC8890394 DOI: 10.1080/19490976.2022.2038854] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 01/14/2022] [Indexed: 02/04/2023] Open
Abstract
Clostridioides difficile is a major nosocomial pathogen that can cause severe, toxin-mediated diarrhea and pseudomembranous colitis. Recent work has shown that C. difficile exhibits heterogeneity in swimming motility and toxin production in vitro through phase variation by site-specific DNA recombination. The recombinase RecV reversibly inverts the flagellar switch sequence upstream of the flgB operon, leading to the ON/OFF expression of flagellum and toxin genes. How this phenomenon impacts C. difficile virulence in vivo remains unknown. We identified mutations in the right inverted repeat that reduced or prevented flagellar switch inversion by RecV. We introduced these mutations into C. difficile R20291 to create strains with the flagellar switch "locked" in either the ON or OFF orientation. These mutants exhibited a loss of flagellum and toxin phase variation during growth in vitro, yielding precisely modified mutants suitable for assessing virulence in vivo. In a hamster model of acute C. difficile infection, the phase-locked ON mutant caused greater toxin accumulation than the phase-locked OFF mutant but did not differ significantly in the ability to cause acute disease symptoms. In contrast, in a mouse model, preventing flagellum and toxin phase variation affected the ability of C. difficile to colonize the intestinal tract and to elicit weight loss, which is attributable to differences in toxin production during infection. These results show that the ability of C. difficile to phase vary flagella and toxins influences colonization and disease development and suggest that the phenotypic variants generated by flagellar switch inversion have distinct capacities for causing disease.
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Affiliation(s)
- Dominika Trzilova
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Mercedes A. H. Warren
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Nicole C. Gadda
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Caitlin L. Williams
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
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OXA-23 β-Lactamase Overexpression in Acinetobacter baumannii Drives Physiological Changes Resulting in New Genetic Vulnerabilities. mBio 2021; 12:e0313721. [PMID: 34872351 PMCID: PMC8649759 DOI: 10.1128/mbio.03137-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
β-Lactamase expression is the major mechanism of resistance to penicillins, cephalosporins, and carbapenems in the multidrug-resistant (MDR) bacterium Acinetobacter baumannii. In fact, stable high-level expression of at least one β-lactamase has been rapidly increasing and reported to occur in up to 98.5% of modern A. baumannii isolates recovered in the clinic. Moreover, the OXA-51 β-lactamase is universally present in the A. baumannii chromosome, suggesting it may have a cellular function beyond antibiotic resistance. However, the consequences associated with OXA β-lactamase overexpression on A. baumannii physiology are not well understood. Using peptidoglycan composition analysis, we show that overexpressing the OXA-23 β-lactamase in A. baumannii drives significant collateral changes with alterations consistent with increased amidase activity. Consequently, we predicted that these changes create new cellular vulnerabilities. As proof of principle, a small screen of random transposon insertions revealed three genes, where mutations resulted in a greater than 19-fold loss of viability when OXA-23 was overexpressed. The identified genes remained conditionally essential even when a catalytically inactive OXA-23 β-lactamase was overexpressed. In addition, we demonstrated a synergistic lethal relationship between OXA-23 overexpression and a CRISPR interference (CRISPRi) knockdown of the essential peptidoglycan synthesis enzyme MurA. Last, OXA-23 overexpression sensitized cells to two inhibitors of peptidoglycan synthesis, d-cycloserine and fosfomycin. Our results highlight the impact of OXA-23 hyperexpression on peptidoglycan integrity and reveal new genetic vulnerabilities, which may represent novel targets for antimicrobial agents specific to MDR A. baumannii and other OXA β-lactamase-overexpressing Enterobacteriaceae, while having no impact on the normal flora. IMPORTANCE Acinetobacter baumannii has become a serious pathogen in both hospital and community settings. The β-lactam class of antibiotics is a primary treatment option for A. baumannii infections, and expression of β-lactamases is the most frequent mechanism of resistance in this bacterium. New approaches to treating multidrug-resistant A. baumannii strains are needed. In this study, we demonstrate that overexpressing the OXA-23 β-lactamase leads to significant collateral changes, where peptidoglycan structure is altered. We have identified genes that become selectively essential in OXA-23-expressing strains and confirmed the relationship between altered peptidoglycan and OXA-23 expression by demonstrating that OXA-23 overexpression sensitizes cells to genetic and chemical inhibition of peptidoglycan synthesis. This work paves the way for the identification of new antimicrobial targets, where inhibitors would selectively kill β-lactamase-expressing strains.
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Acinetobacter baumannii regulates its stress responses via the BfmRS two-component regulatory system. J Bacteriol 2021; 204:e0049421. [PMID: 34871031 DOI: 10.1128/jb.00494-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a common nosocomial pathogen that utilizes numerous mechanisms to aid its survival in both the environment and in the host. Coordination of such mechanisms requires an intricate regulatory network. We report here that A. baumannii can directly regulate several stress-related pathways via the two-component regulatory system, BfmRS. Similar to previous studies, results from transcriptomic analysis showed that mutation of the BfmR response regulator causes dysregulation of genes required for the oxidative stress response, the osmotic stress response, the misfolded protein/heat shock response, Csu pili/fimbriae production, and capsular polysaccharide biosynthesis. We also found that the BfmRS system is involved in controlling siderophore biosynthesis and transport, and type IV pili production. We provide evidence that BfmR binds to various stress-related promoter regions and show that BfmR alone can directly activate transcription of some stress-related genes. Additionally, we show that the BfmS sensor kinase acts as a BfmR phosphatase to negatively regulate BfmR activity. This work highlights the importance of the BfmRS system in promoting survival of A. baumannii. Importance Acinetobacter baumannii is a nosocomial pathogen that has extremely high rates of multidrug resistance. This organism's ability to endure stressful conditions is a key part of its ability to spread in the hospital environment and cause infections. Unlike other members of the γ-proteobacteria, A. baumannii does not encode a homolog of the RpoS sigma factor to coordinate its stress response. Here, we demonstrate that the BfmRS two-component system directly controls the expression of multiple stress resistance genes. Our findings suggest that BfmRS is central to a unique scheme of general stress response regulation by A. baumannii.
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Whiteway C, Breine A, Philippe C, Van der Henst C. Acinetobacter baumannii. Trends Microbiol 2021; 30:199-200. [PMID: 34836792 DOI: 10.1016/j.tim.2021.11.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/25/2021] [Accepted: 11/08/2021] [Indexed: 12/24/2022]
Affiliation(s)
- Clémence Whiteway
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Anke Breine
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Chantal Philippe
- Research Unit in the Biology of Microorganisms (URBM), NARILIS, University of Namur (UNamur), Namur, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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