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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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Wang H, Xu Q, Heng H, Zhao W, Ni H, Chen K, Wai Chan BK, Tang Y, Xie M, Peng M, Chi Chan EW, Yang G, Chen S. High mortality of Acinetobacter baumannii infection is attributed to macrophage-mediated induction of cytokine storm but preventable by naproxen. EBioMedicine 2024; 108:105340. [PMID: 39303669 PMCID: PMC11437915 DOI: 10.1016/j.ebiom.2024.105340] [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: 12/15/2023] [Revised: 08/25/2024] [Accepted: 08/30/2024] [Indexed: 09/22/2024] Open
Abstract
BACKGROUND The continuous emergence of multidrug-resistant (MDR) Acinetobacter baumannii (Ab) strains poses further challenges in its control and clinical management. It is necessary to decipher the mechanisms underlying the high mortality of Ab infections to explore unconventional strategies for controlling outbreaks of drug-resistant infections. METHODS The immune responses of Ab sepsis infection were investigated using flow cytometry, RNA-seq, qRT-PCR, and ELISA and scRNA-seq. The detailed pathways mediating Ab immune responses were also depicted and a specific therapy was developed based on the understanding of the mechanisms underlying Ab-induced cytokine storms. FINDINGS The results highlighted the critical role of alveolar and interstitial macrophages as targets of Ab during the infection process. These cells were found to undergo polarization towards the M1 phenotype, triggering a cytokine storm that eventually caused the death of the host. The polarization and excessive inflammatory response mediated by macrophages were mainly regulated by the TLR2/Myd88/NF-κB signaling pathway. Suppression of Ab-triggered inflammatory responses and M1 polarization by the drug naproxen (NPXS) was shown to confer full protection of mice from lethal infections. INTERPRETATION The findings in this work depict the major mechanisms underlying the high mortality rate of Ab infections and highlight the clinical potential application of anti-inflammatory drugs or immunosuppressants in reducing the mortality of such infections, including those caused by MDR strains. FUNDING Funding sources are described in the acknowledgments section.
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Affiliation(s)
- Han Wang
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China; State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Qi Xu
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Heng Heng
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China; State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Wenxing Zhao
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Hongyuhang Ni
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China; State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Kaichao Chen
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Bill Kwan Wai Chan
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Yang Tang
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China; State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Miaomiao Xie
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Mingxiu Peng
- Shenzhen Key Lab for Food Biological Safety Control, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China
| | - Edward Wai Chi Chan
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Guan Yang
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
| | - Sheng Chen
- State Key Lab of Chemical Biology and Drug Discovery and the Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China; Shenzhen Key Lab for Food Biological Safety Control, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China.
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Shashkov AS, Arbatsky NP, Senchenkova SN, Kasimova AA, Dmitrenok AS, Shneider MM, Knirel YA, Hall RM, Kenyon JJ. Characterization of the carbapenem-resistant Acinetobacter baumannii clinical reference isolate BAL062 (CC2:KL58:OCL1): resistance properties and capsular polysaccharide structure. mSystems 2024:e0094124. [PMID: 39254035 DOI: 10.1128/msystems.00941-24] [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: 07/14/2024] [Accepted: 08/19/2024] [Indexed: 09/11/2024] Open
Abstract
The carbapenem-resistant Acinetobacter baumannii isolate BAL062 is a clinical reference isolate used in several recent experimental studies. It is from a ventilator-associated pneumonia (VAP) patient in an intensive care unit at the Hospital for Tropical Diseases (HTD), Ho Chi Minh City, Vietnam in 2009. Here, BAL062 was found to belong to the B sub-lineage of global clone 2 (GC2) isolates in the previously reported outbreak (2008 and 2012) of carbapenem-resistant VAP A. baumannii at the HTD. While related sub-lineage B outbreak isolates were extensively antibiotic-resistant and carry GC2-associated genomic resistance islands, AbGRI1, AbGRI2, and AbGRI3, BAL062 has lost AbGRI3 and three aminoglycoside resistance genes, armA, aacA4, and aphA1, leading to amikacin, tobramycin and kanamycin susceptibility. The location of Tn2008VAR found in the chromosome of this sub-lineage was also corrected. Like many of the outbreak isolates, BAL062 carries the KL58 gene cluster at the capsular polysaccharide (CPS) synthesis locus and an annotation key is provided. As information about K type is important for the development of novel CPS-targeting therapies, the BAL062 K58-type CPS structure was established using NMR spectroscopy. It is most closely related to K2 and K93, sharing similar configurations and linkages between K units, and contains the rare higher monosaccharide, 5,7-diacetamido-3,5,7,9-tetradeoxy-d-glycero-l-manno-non-2-ulosonic acid (5,7-di-N-acetyl-8-epipseudaminic acid; 8ePse5Ac7Ac), the 8-epimer of Pse5Ac7Ac (5,7-di-N-acetylpseudaminic acid). Inspection of publicly available A. baumannii genomes revealed a wide distribution of the KL58 locus in geographically diverse isolates belonging to several sequence types that were recovered over two decades from clinical, animal, and environmental sources.IMPORTANCEMany published experimental studies aimed at developing a clearer understanding of the pathogenicity of carbapenem-resistant Acinetobacter baumannii strains currently causing treatment failure due to extensive antibiotic resistance are undertaken using historic, laboratory-adapted isolates. However, it is ideal if not imperative that recent clinical isolates are used in such studies. The clinical reference isolate characterized here belongs to the dominant A. baumannii GC2 clone causing extensively resistant infections and has been used in various recent studies. The correlation of resistance profiles and resistance gene data is key to identifying genes available for gene knockout and complementation analyses, and we have mapped the antibiotic resistance genes to find candidates. Novel therapies, such as bacteriophage or monoclonal antibody therapies, currently under investigation as alternatives or adjuncts to antibiotic treatment to combat difficult-to-treat CRAb infections often exhibit specificity for specific structural epitopes of the capsular polysaccharide (CPS), the outer-most polysaccharide layer. Here, we have solved the structure of the CPS type found in BAL062 and other extensively resistant isolates. As consistent gene naming and annotation are important for locus identification and interpretation of experimental studies, we also have correlated automatic annotations to the standard gene names.
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Affiliation(s)
- Alexander S Shashkov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Nikolay P Arbatsky
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Sof'ya N Senchenkova
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Anastasiya A Kasimova
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Andrei S Dmitrenok
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Mikhail M Shneider
- M. M. Shemyakin & Y. A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Yuriy A Knirel
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Ruth M Hall
- School of Life and Environmental Science, The University of Sydney, Sydney, Australia
| | - Johanna J Kenyon
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- School of Pharmacy and Medical Sciences, Health Group, Griffith University, Gold Coast, Australia
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Sabatini A, Lucidi M, Ciolfi S, Vuotto C, De Bardi M, Visca P, Battistini L, Visaggio D, Volpe E. Innate immune mechanisms promote human response to Acinetobacter baumannii infection. Eur J Immunol 2024:e2451170. [PMID: 39072714 DOI: 10.1002/eji.202451170] [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: 04/02/2024] [Revised: 07/15/2024] [Accepted: 07/17/2024] [Indexed: 07/30/2024]
Abstract
Acinetobacter baumannii is an opportunistic Gram-negative bacterium representing one of the leading causes of ventilator-associated pneumonia. The development of pneumonia results from a complex interplay between pathogens and pulmonary innate mucosal immunity. Therefore, the knowledge of the host immune responses is pivotal for the development of effective therapeutics to treat A. baumannii infections. Previous studies were conducted using cell lines and animal models, but a comprehensive understanding of the interaction between A. baumannii and primary human immune cells is still lacking. To bridge this gap, we investigated the response of primary monocytes, macrophages, and dendritic cells to the A. baumannii-type strain and an epidemic clinical isolate. We found that all immune cells trigger different responses when interacting with A. baumannii. In particular, macrophages and monocytes mediate bacterial clearance, whereas monocytes and dendritic cells activate a late response through the production of cytokines, chemokines, and the expression of co-stimulatory molecules. The epidemic strain induces lower expression of interleukin-10 and CD80 compared with the type strain, potentially constituting two immune evasion strategies.
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Affiliation(s)
- Andrea Sabatini
- Molecular Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Massimiliano Lucidi
- Department of Science, University Roma Tre, Rome, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
| | - Serena Ciolfi
- Molecular Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Claudia Vuotto
- Neuromicrobiology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Marco De Bardi
- Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Paolo Visca
- Department of Science, University Roma Tre, Rome, Italy
- Molecular Microbiology and Microbiomics, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Luca Battistini
- Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Daniela Visaggio
- Department of Science, University Roma Tre, Rome, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
- Molecular Microbiology and Microbiomics, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Elisabetta Volpe
- Molecular Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
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Li Y, Cui Y, Song K, Shen L, Xiao L, Jin J, Zhao Y, Yan Y, Zhao S, Yao W, Wang S, Du Z, Yang R, Yi B, Song Y. TagP, a PAAR-domain containing protein, plays roles in the fitness and virulence of Acinetobacter baumannii. Front Cell Infect Microbiol 2024; 14:1379106. [PMID: 39193505 PMCID: PMC11348943 DOI: 10.3389/fcimb.2024.1379106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 07/03/2024] [Indexed: 08/29/2024] Open
Abstract
Background Type VI secretion system (T6SS) is widely present in Gram-negative bacteria and directly mediates antagonistic prokaryote interactions. PAAR (proline-alanine-alanine-arginine repeats) proteins have been proven essential for T6SS-mediated secretion and target cell killing. Although PAAR proteins are commonly found in A. baumannii, their biological functions are not fully disclosed yet. In this study, we investigated the functions of a PAAR protein termed TagP (T6SS-associated-gene PAAR), encoded by the gene ACX60_RS09070 outside the core T6SS locus of A. baumannii strain ATCC 17978. Methods In this study, tagP null and complement A. baumannii ATCC 17978 strains were constructed. The influence of TagP on T6SS function was investigated through Hcp detection and bacterial competition assay; the influence on environmental fitness was studied through in vitro growth, biofilm formation assay, surface motility assay, survivability in various simulated environmental conditions; the influence on pathogenicity was explored through cell adhesion and invasion assays, intramacrophage survival assay, serum survival assay, and G. melonella Killing assays. Quantitative transcriptomic and proteomic analyses were utilized to observe the global impact of TagP on bacterial status. Results Compared with the wildtype strain, the tagP null mutant was impaired in several tested phenotypes such as surface motility, biofilm formation, tolerance to adverse environments, adherence to eukaryotic cells, endurance to serum complement killing, and virulence to Galleria melonella. Notably, although RNA-Seq and proteomics analysis revealed that many genes were significantly down-regulated in the tagP null mutant compared to the wildtype strain, there is no significant difference in their antagonistic abilities. We also found that Histone-like nucleoid structuring protein (H-NS) was significantly upregulated in the tagP null mutant at both mRNA and protein levels. Conclusions This study enriches our understanding of the biofunction of PAAR proteins in A. baumannii. The results indicates that TagP involved in a unique modulation of fitness and virulence control in A. baumannii, it is more than a classic PAAR protein involved in T6SS, while how TagP play roles in the fitness and virulence of A. baumannii needs further investigation to clarify.
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Affiliation(s)
- Yanbing Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yiming Cui
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kai Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Leiming Shen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Liting Xiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Junyan Jin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanting Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shengyuan Zhao
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Wenwu Yao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zongmin Du
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Bin Yi
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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Kunkle DE, Cai Y, Eichman BF, Skaar EP. An interstrand DNA crosslink glycosylase aids Acinetobacter baumannii pathogenesis. Proc Natl Acad Sci U S A 2024; 121:e2402422121. [PMID: 38923984 PMCID: PMC11228520 DOI: 10.1073/pnas.2402422121] [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: 02/04/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
Maintenance of DNA integrity is essential to all forms of life. DNA damage generated by reaction with genotoxic chemicals results in deleterious mutations, genome instability, and cell death. Pathogenic bacteria encounter several genotoxic agents during infection. In keeping with this, the loss of DNA repair networks results in virulence attenuation in several bacterial species. Interstrand DNA crosslinks (ICLs) are a type of DNA lesion formed by covalent linkage of opposing DNA strands and are particularly toxic as they interfere with replication and transcription. Bacteria have evolved specialized DNA glycosylases that unhook ICLs, thereby initiating their repair. In this study, we describe AlkX, a DNA glycosylase encoded by the multidrug resistant pathogen Acinetobacter baumannii. AlkX exhibits ICL unhooking activity similar to that of its Escherichia coli homolog YcaQ. Interrogation of the in vivo role of AlkX revealed that its loss sensitizes cells to DNA crosslinking and impairs A. baumannii colonization of the lungs and dissemination to distal tissues during pneumonia. These results suggest that AlkX participates in A. baumannii pathogenesis and protects the bacterium from stress conditions encountered in vivo. Consistent with this, we found that acidic pH, an environment encountered during host colonization, results in A. baumannii DNA damage and that alkX is induced by, and contributes to, defense against acidic conditions. Collectively, these studies reveal functions for a recently described class of proteins encoded in a broad range of pathogenic bacterial species.
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Affiliation(s)
- Dillon E. Kunkle
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN37232
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN37232
| | - Yujuan Cai
- Department of Biological Sciences, Vanderbilt University, Nashville, TN37232
| | - Brandt F. Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN37232
- Department of Biochemistry, Vanderbilt University, Nashville, TN37232
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN37232
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Biological Sciences, Vanderbilt University, Nashville, TN37232
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Ellison TJ, Ellison CK. DNA binding is rate-limiting for natural transformation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.06.597730. [PMID: 38895488 PMCID: PMC11185590 DOI: 10.1101/2024.06.06.597730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Bacteria take up environmental DNA using dynamic appendages called type IV pili (T4P) to elicit horizontal gene transfer in a process called natural transformation. Natural transformation is widespread amongst bacteria yet determining how different factors universally contribute to or limit this process across species has remained challenging. Here we show that Acinetobacter baylyi, the most naturally transformable species, is highly transformable due to its ability to robustly bind nonspecific DNA via a dedicated orphan minor pilin, FimT. We show that, compared to its homologues, A. baylyi FimT contains multiple positively charged residues that additively promote DNA binding efficiency. Expression of A. baylyi FimT in a closely related Acinetobacter pathogen is sufficient to substantially improve its capacity for natural transformation, demonstrating that T4P-DNA binding is a rate-limiting step in this process. These results demonstrate the importance of T4P-DNA binding efficiency in driving natural transformation, establishing a key factor limiting horizontal gene transfer.
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Darby EM, Moran RA, Holden E, Morris T, Harrison F, Clough B, McInnes RS, Schneider L, Frickel EM, Webber MA, Blair JMA. Differential development of antibiotic resistance and virulence between Acinetobacter species. mSphere 2024; 9:e0010924. [PMID: 38578105 PMCID: PMC11237425 DOI: 10.1128/msphere.00109-24] [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: 02/10/2024] [Accepted: 03/13/2024] [Indexed: 04/06/2024] Open
Abstract
The two species that account for most cases of Acinetobacter-associated bacteremia in the United Kingdom are Acinetobacter lwoffii, often a commensal but also an emerging pathogen, and Acinetobacter baumannii, a well-known antibiotic-resistant species. While these species both cause similar types of human infection and occupy the same niche, A. lwoffii (unlike A. baumannii) has thus far remained susceptible to antibiotics. Comparatively little is known about the biology of A. lwoffii, and this is the largest study on it conducted to date, providing valuable insights into its behaviour and potential threat to human health. This study aimed to explain the antibiotic susceptibility, virulence, and fundamental biological differences between these two species. The relative susceptibility of A. lwoffii was explained as it encoded fewer antibiotic resistance and efflux pump genes than A. baumannii (9 and 30, respectively). While both species had markers of horizontal gene transfer, A. lwoffii encoded more DNA defense systems and harbored a far more restricted range of plasmids. Furthermore, A. lwoffii displayed a reduced ability to select for antibiotic resistance mutations, form biofilm, and infect both in vivo and in in vitro models of infection. This study suggests that the emerging pathogen A. lwoffii has remained susceptible to antibiotics because mechanisms exist to make it highly selective about the DNA it acquires, and we hypothesize that the fact that it only harbors a single RND system restricts the ability to select for resistance mutations. This provides valuable insights into how development of resistance can be constrained in Gram-negative bacteria. IMPORTANCE Acinetobacter lwoffii is often a harmless commensal but is also an emerging pathogen and is the most common cause of Acinetobacter-derived bloodstream infections in England and Wales. In contrast to the well-studied and often highly drug-resistant A. baumannii, A. lwoffii has remained susceptible to antibiotics. This study explains why this organism has not evolved resistance to antibiotics. These new insights are important to understand why and how some species develop antibiotic resistance, while others do not, and could inform future novel treatment strategies.
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Affiliation(s)
- Elizabeth M. Darby
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Robert A. Moran
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Emma Holden
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Theresa Morris
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Freya Harrison
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Barbara Clough
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ross S. McInnes
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Ludwig Schneider
- Centre for Electron Microscopy, University of Birmingham, Birmingham, United Kingdom
| | - Eva M. Frickel
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Mark A. Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, Norfolk, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Jessica M. A. Blair
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
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Feng Z, Wang L, Guan Q, Chu X, Luo ZQ. Acinetobacter baumannii coordinates central metabolism, plasmid dissemination, and virulence by sensing nutrient availability. mBio 2023; 14:e0227623. [PMID: 37855599 PMCID: PMC10746170 DOI: 10.1128/mbio.02276-23] [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: 08/28/2023] [Accepted: 09/01/2023] [Indexed: 10/20/2023] Open
Abstract
IMPORTANCE Plasmid conjugation is known to be an energy-expensive process, but our understanding of the molecular linkage between conjugation and metabolism is limited. Our finding reveals that Acinetobacter baumannii utilizes a two-component system to co-regulate metabolism, plasmid transfer, and virulence by sensing reaction intermediates of key metabolic pathways, which suggests that nutrient availability dictates not only bacterial proliferation but also horizontal gene transfer. The identification of Dot/Icm-like proteins as components of a conjugation system involved in the dissemination of antibiotic-resistance genes by A. baumannii has provided important targets for the development of agents capable of inhibiting virulence and the spread of anti-microbial-resistance genes in bacterial communities.
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Affiliation(s)
- Zhengshan Feng
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Lidong Wang
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Qingtian Guan
- Bioinformatics Laboratory, The First Hospital of Jilin University, Changchun, China
| | - Xiao Chu
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
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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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11
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Pfefferle K, Averhoff B. Wax Ester and Triacylglycerol Production in Acinetobacter baumannii: Role in Osmostress Protection, Reactive Oxygen Species, and Antibiotic Sensitivity. ACS Infect Dis 2023; 9:2093-2104. [PMID: 37883671 DOI: 10.1021/acsinfecdis.3c00214] [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] [Indexed: 10/28/2023]
Abstract
Wax esters (WEs) are neutral lipids that are produced by many different bacteria as potential carbon and energy storage compounds. Comparatively little is known about the role of WE in pathogenic bacteria. The opportunistic pathogen Acinetobacter baumannii is a major cause of hospital-acquired infections worldwide. Salt and desiccation resistance foster A. baumannii infections such as urinary tract infections and allow for reinfection when bacteria are taken up from dry surfaces in the hospital environment. Here we report on WE and triacylglycerol (TAG) production in A. baumannii as a response to nitrogen limitation and high salt stress. Fatty acids and fatty alcohols with chain lengths of C16 and C18 were identified as the most prominent WE constituents. We identified the terminal key enzyme of WE biosynthesis, the bifunctional wax ester synthase/acylCoA:diacylglycerol acyltransferase (WS/DGAT) encoded by the wax/dgat gene, and demonstrated that transcription of wax/dgat and production of WS/DGAT are independent of the nitrogen concentration. A Δwax/dgat mutant was impaired in growth in the presence of high salt concentration and was more sensitive to imipenem and reactive oxygen species.
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Affiliation(s)
- Katharina Pfefferle
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, 60438 Frankfurt, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, 60438 Frankfurt, Germany
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12
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McGuffey JC, Jackson-Litteken CD, Di Venanzio G, Zimmer AA, Lewis JM, Distel JS, Kim KQ, Zaher HS, Alfonzo J, Scott NE, Feldman MF. The tRNA methyltransferase TrmB is critical for Acinetobacter baumannii stress responses and pulmonary infection. mBio 2023; 14:e0141623. [PMID: 37589464 PMCID: PMC10653896 DOI: 10.1128/mbio.01416-23] [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: 06/09/2023] [Accepted: 07/10/2023] [Indexed: 08/18/2023] Open
Abstract
IMPORTANCE As deficiencies in tRNA modifications have been linked to human diseases such as cancer and diabetes, much research has focused on the modifications' impacts on translational regulation in eukaryotes. However, the significance of tRNA modifications in bacterial physiology remains largely unexplored. In this paper, we demonstrate that the m7G tRNA methyltransferase TrmB is crucial for a top-priority pathogen, Acinetobacter baumannii, to respond to stressors encountered during infection, including oxidative stress, low pH, and iron deprivation. We show that loss of TrmB dramatically attenuates a murine pulmonary infection. Given the current efforts to use another tRNA methyltransferase, TrmD, as an antimicrobial therapeutic target, we propose that TrmB, and other tRNA methyltransferases, may also be viable options for drug development to combat multidrug-resistant A. baumannii.
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Affiliation(s)
- Jenna C. McGuffey
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Clay D. Jackson-Litteken
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Aubree A. Zimmer
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Jessica M. Lewis
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Jesus S. Distel
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Kyusik Q. Kim
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Hani S. Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Juan Alfonzo
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Nichollas E. Scott
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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13
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Vaca DJ, Frenzel F, Ballhorn W, Torres SG, Leisegang MS, Günther S, Bender D, Kraiczy P, Göttig S, Kempf VAJ. Adhesion of human pathogenic bacteria to endothelial cells is facilitated by fibronectin interaction. Microbes Infect 2023; 25:105172. [PMID: 37343664 DOI: 10.1016/j.micinf.2023.105172] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 06/23/2023]
Abstract
Human pathogenic bacteria circulating in the bloodstream need to find a way to interact with endothelial cells (ECs) lining the blood vessels to infect and colonise the host. The extracellular matrix (ECM) of ECs might represent an attractive initial target for bacterial interaction, as many bacterial adhesins have reported affinities to ECM proteins, in particular to fibronectin (Fn). Here, we analysed the general role of EC-expressed Fn for bacterial adhesion. For this, we evaluated the expression levels of ECM coding genes in different ECs, revealing that Fn is the highest expressed gene and thereby, it is highly abundant in the ECM environment of ECs. The role of Fn as a mediator in bacterial cell-host adhesion was evaluated in adhesion assays of Acinetobacter baumannii, Bartonella henselae, Borrelia burgdorferi, and Staphylococcus aureus to ECs. The assays demonstrated that bacteria colocalised with Fn fibres, as observed by confocal laser scanning microscopy. Fn removal from the ECM environment (FN1 knockout ECs) diminished bacterial adherence to ECs in both static and dynamic adhesion assays to varying extents, as evaluated via absolute quantification using qPCR. Interactions between adhesins and Fn might represent the crucial step for the adhesion of human-pathogenic Gram-negative and Gram-positive bacteria targeting the ECs as a niche of infection.
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Affiliation(s)
- Diana J Vaca
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Fabienne Frenzel
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Wibke Ballhorn
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Sara Garcia Torres
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Matthias S Leisegang
- Institute for Cardiovascular Physiology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
| | - Stefan Günther
- Max Planck Institute for Heart and Lung Research, Parkstraße 1, 61231, Bad Nauheim, Germany.
| | - Daniela Bender
- Federal Institute for Vaccines and Biomedicines, Department of Virology, Paul Ehrlich Institute, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany.
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Stephan Göttig
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Volkhard A J Kempf
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
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14
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Distel JS, Di Venanzio G, Mackel JJ, Rosen DA, Feldman MF. Replicative Acinetobacter baumannii strains interfere with phagosomal maturation by modulating the vacuolar pH. PLoS Pathog 2023; 19:e1011173. [PMID: 37294840 DOI: 10.1371/journal.ppat.1011173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/23/2023] [Indexed: 06/11/2023] Open
Abstract
Bacterial pneumonia is a common infection of the lower respiratory tract that can afflict patients of all ages. Multidrug-resistant strains of Acinetobacter baumannii are increasingly responsible for causing nosocomial pneumonias, thus posing an urgent threat. Alveolar macrophages play a critical role in overcoming respiratory infections caused by this pathogen. Recently, we and others have shown that new clinical isolates of A. baumannii, but not the common lab strain ATCC 19606 (19606), can persist and replicate in macrophages within spacious vacuoles that we called Acinetobacter Containing Vacuoles (ACV). In this work, we demonstrate that the modern A. baumannii clinical isolate 398, but not the lab strain 19606, can infect alveolar macrophages and produce ACVs in vivo in a murine pneumonia model. Both strains initially interact with the alveolar macrophage endocytic pathway, as indicated by EEA1 and LAMP1 markers; however, the fate of these strains diverges at a later stage. While 19606 is eliminated in an autophagy pathway, 398 replicates in ACVs and are not degraded. We show that 398 reverts the natural acidification of the phagosome by secreting large amounts of ammonia, a by-product of amino acid catabolism. We propose that this ability to survive within macrophages may be critical for the persistence of clinical A. baumannii isolates in the lung during a respiratory infection.
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Affiliation(s)
- Jesus S Distel
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Joseph J Mackel
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - David A Rosen
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
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15
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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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16
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Distel JS, Di Venanzio G, Mackel JJ, Rosen DA, Feldman MF. Replicative Acinetobacter baumannii strains interfere with phagosomal maturation by modulating the vacuolar pH. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526753. [PMID: 36778331 PMCID: PMC9915592 DOI: 10.1101/2023.02.02.526753] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bacterial pneumonia is a common infection of the lower respiratory tract that can afflict patients of all ages. Multidrug-resistant strains of Acinetobacter baumannii are increasingly responsible for causing nosocomial pneumonias, thus posing an urgent threat. Alveolar macrophages play a critical role in overcoming respiratory infections caused by this pathogen. Recently, we and others have shown that new clinical isolates of A. baumannii , but not the common lab strain ATCC 19606 (19606), can persist and replicate in macrophages within spacious vacuoles that we called A cinetobacter C ontaining V acuoles (ACV). In this work, we demonstrate that the modern A. baumannii clinical isolate 398, but not the lab strain 19606, can infect alveolar macrophages and produce ACVs in vivo in a murine pneumonia model. Both strains initially interact with the alveolar macrophage endocytic pathway, as indicated by EEA1 and LAMP1 markers; however, the fate of these strains diverges at a later stage. While 19606 is eliminated in an autophagy pathway, 398 replicates in ACVs and are not degraded. We show that 398 reverts the natural acidification of the phagosome by secreting large amounts of ammonia, a by-product of amino acid catabolism. We propose that this ability to survive within macrophages may be critical for the persistence of clinical A. baumannii isolates in the lung during a respiratory infection.
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Affiliation(s)
- Jesus S. Distel
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Joseph J. Mackel
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - David A Rosen
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
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17
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Hazen JE, Di Venanzio G, Hultgren SJ, Feldman MF. Catheterization of mice triggers resurgent urinary tract infection seeded by a bladder reservoir of Acinetobacter baumannii. Sci Transl Med 2023; 15:eabn8134. [PMID: 36630484 PMCID: PMC10464790 DOI: 10.1126/scitranslmed.abn8134] [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: 12/21/2021] [Accepted: 10/11/2022] [Indexed: 01/13/2023]
Abstract
The antibiotic-resistant bacterium Acinetobacter baumannii is a leading cause of hospital-associated infections. Despite surveillance and infection control efforts, new A. baumannii strains are regularly isolated from health care facilities worldwide. In a mouse model of urinary tract infection, we found that mice infected with A. baumannii displayed high bacterial burdens in urine for several weeks. Two months after the resolution of A. baumannii infection, inserting a catheter into the bladder of mice with resolved infection led to the resurgence of a same-strain urinary tract infection in ~53% of the mice within 24 hours. We identified intracellular A. baumannii bacteria in the bladder epithelial cells of mice with resolved infection, which we propose could act as a host reservoir that was activated upon insertion of a catheter, leading to a resurgent secondary infection.
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Affiliation(s)
- Jennie E. Hazen
- Department of Molecular Microbiology, Washington University School of Medicine; St Louis, MO 63110, USA
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine; St Louis, MO 63110 USA
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine; St Louis, MO 63110, USA
| | - Scott J. Hultgren
- Department of Molecular Microbiology, Washington University School of Medicine; St Louis, MO 63110, USA
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine; St Louis, MO 63110 USA
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine; St Louis, MO 63110, USA
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18
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Rafei R, Koong J, Osman M, Al Atrouni A, Hamze M, Hamidian M. Analysis of pCl107 a large plasmid carried by an ST25 Acinetobacter baumannii strain reveals a complex evolutionary history and links to multiple antibiotic resistance and metabolic pathways. FEMS MICROBES 2022; 3:xtac027. [PMID: 37332503 PMCID: PMC10117892 DOI: 10.1093/femsmc/xtac027] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/13/2022] [Accepted: 11/14/2022] [Indexed: 09/14/2023] Open
Abstract
Acinetobacter baumannii has successfully spread during the last decades as one of the main critically important pathogens. However, many aspects including plasmids, are still under-investigated. Here, we report the complete sequence of an Acinetobacter baumannii strain, belonging to the ST25IP (Institut Pasteur) sequence type recovered in 2012 in Lebanon, using a combination of Illumina MiSeq and Oxford Nanopore sequencing and a hybrid assembly approach. This strain (Cl107) carries a 198 kb plasmid called pCl107 that encodes the MPFI conjugative transfer system. The plasmid carries the aacA1, aacC2, sul2, strAB, and tetA(B) antibiotic resistance genes. pCl107 region encompassing the sul2, strAB, tetA(B) is closely related to AbGRI1 chromosomal resistance islands, which are widespread in A. baumannii strains belonging to Global Clone 2. The resistance region found in pCl107 is one of the missing links in the evolutionary history of the AbGRI1 islands. pCl107 also contains a BREX Type 1 region and represents one of the two main evolution patterns observed in BREX clusters found in plasmids related to pCl107. pCl107 also harbours a ptx phosphonate metabolism module, which plays an ancestral structure compared to other large plasmids in ST25 strains. While the uric acid metabolic module found in pCl107 is incomplete, we identified possible ancestors from plasmids and chromosomes of Acinetobacter spp. Our analyses indicate a complex evolutionary history of plasmids related to pCl107 with many links to multiple antibiotic resistance and metabolic pathways.
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Affiliation(s)
- Rayane Rafei
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science & Technology, Faculty of Public Health, Lebanese University, Tripoli 1300, Lebanon
| | - Jonathan Koong
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo NSW 2007, Australia
| | - Marwan Osman
- Cornell Atkinson Center for Sustainability, Cornell University, Ithaca, NY 14853, United States
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States
| | - Ahmad Al Atrouni
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science & Technology, Faculty of Public Health, Lebanese University, Tripoli 1300, Lebanon
| | - Monzer Hamze
- Laboratoire Microbiologie Santé et Environnement (LMSE), Doctoral School of Science & Technology, Faculty of Public Health, Lebanese University, Tripoli 1300, Lebanon
| | - Mehrad Hamidian
- Australian Institute for Microbiology and Infection, University of Technology Sydney, Ultimo NSW 2007, Australia
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Krysenko S, Wohlleben W. Polyamine and Ethanolamine Metabolism in Bacteria as an Important Component of Nitrogen Assimilation for Survival and Pathogenicity. Med Sci (Basel) 2022; 10:40. [PMID: 35997332 PMCID: PMC9397018 DOI: 10.3390/medsci10030040] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022] Open
Abstract
Nitrogen is an essential element required for bacterial growth. It serves as a building block for the biosynthesis of macromolecules and provides precursors for secondary metabolites. Bacteria have developed the ability to use various nitrogen sources and possess two enzyme systems for nitrogen assimilation involving glutamine synthetase/glutamate synthase and glutamate dehydrogenase. Microorganisms living in habitats with changeable availability of nutrients have developed strategies to survive under nitrogen limitation. One adaptation is the ability to acquire nitrogen from alternative sources including the polyamines putrescine, cadaverine, spermidine and spermine, as well as the monoamine ethanolamine. Bacterial polyamine and monoamine metabolism is not only important under low nitrogen availability, but it is also required to survive under high concentrations of these compounds. Such conditions can occur in diverse habitats such as soil, plant tissues and human cells. Strategies of pathogenic and non-pathogenic bacteria to survive in the presence of poly- and monoamines offer the possibility to combat pathogens by using their capability to metabolize polyamines as an antibiotic drug target. This work aims to summarize the knowledge on poly- and monoamine metabolism in bacteria and its role in nitrogen metabolism.
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Affiliation(s)
- Sergii Krysenko
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Department of Microbiology and Biotechnology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany;
- Cluster of Excellence ‘Controlling Microbes to Fight Infections’, University of Tübingen, 72076 Tübingen, Germany
| | - Wolfgang Wohlleben
- Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Department of Microbiology and Biotechnology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany;
- Cluster of Excellence ‘Controlling Microbes to Fight Infections’, University of Tübingen, 72076 Tübingen, Germany
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20
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InvL, an Invasin-Like Adhesin, Is a Type II Secretion System Substrate Required for Acinetobacter baumannii Uropathogenesis. mBio 2022; 13:e0025822. [PMID: 35638734 PMCID: PMC9245377 DOI: 10.1128/mbio.00258-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen of growing concern, as isolates are commonly multidrug resistant. While A. baumannii is most frequently associated with pulmonary infections, a significant proportion of clinical isolates come from urinary sources, highlighting its uropathogenic potential. The type II secretion system (T2SS) of commonly used model Acinetobacter strains is important for virulence in various animal models, but the potential role of the T2SS in urinary tract infection (UTI) remains unknown. Here, we used a catheter-associated UTI (CAUTI) model to demonstrate that a modern urinary isolate, UPAB1, requires the T2SS for full virulence. A proteomic screen to identify putative UPAB1 T2SS effectors revealed an uncharacterized lipoprotein with structural similarity to the intimin-invasin family, which serve as type V secretion system (T5SS) adhesins required for the pathogenesis of several bacteria. This protein, designated InvL, lacked the β-barrel domain associated with T5SSs but was confirmed to require the T2SS for both surface localization and secretion. This makes InvL the first identified T2SS effector belonging to the intimin-invasin family. InvL was confirmed to be an adhesin, as the protein bound to extracellular matrix components and mediated adhesion to urinary tract cell lines in vitro. Additionally, the invL mutant was attenuated in the CAUTI model, indicating a role in Acinetobacter uropathogenesis. Finally, bioinformatic analyses revealed that InvL is present in nearly all clinical isolates belonging to international clone 2, a lineage of significant clinical importance. In all, we conclude that the T2SS substrate InvL is an adhesin required for A. baumannii uropathogenesis. IMPORTANCE While pathogenic Acinetobacter can cause various infections, we recently found that 20% of clinical isolates come from urinary sources. Despite the clinical relevance of Acinetobacter as a uropathogen, few virulence factors involved in urinary tract colonization have been defined. Here, we identify a novel type II secretion system effector, InvL, which is required for full uropathogenesis by a modern urinary isolate. Although InvL has predicted structural similarity to the intimin-invasin family of autotransporter adhesins, InvL is predicted to be anchored to the membrane as a lipoprotein. Similar to other invasin homologs, however, we demonstrate that InvL is a bona fide adhesin capable of binding extracellular matrix components and mediating adhesion to urinary tract cell lines. In all, this work establishes InvL as an adhesin important for Acinetobacter's urinary tract virulence and represents the first report of a type II secretion system effector belonging to the intimin-invasin family.
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Abstract
The spread of antibiotic-resistant Acinetobacter baumannii poses a significant threat to public health worldwide. This nosocomial bacterial pathogen can be associated with life-threatening infections, particularly in intensive care units. A. baumannii is mainly described as an extracellular pathogen with restricted survival within cells. This study shows that a subset of A. baumannii clinical isolates extensively multiply within nonphagocytic immortalized and primary cells without the induction of apoptosis and with bacterial clusters visible up to 48 h after infection. This phenotype was observed for the A. baumannii C4 strain associated with high mortality in a hospital outbreak and the A. baumannii ABC141 strain, which was isolated from the skin but was found to be hyperinvasive. Intracellular multiplication of these A. baumannii strains occurred within spacious single membrane-bound vacuoles, labeled with the lysosomal associate membrane protein (LAMP1). However, these compartments excluded lysotracker, an indicator of acidic pH, suggesting that A. baumannii can divert its trafficking away from the lysosomal degradative pathway. These compartments were also devoid of autophagy features. A high-content microscopy screen of 43 additional A. baumannii clinical isolates highlighted various phenotypes, and (i) the majority of isolates remained extracellular, (ii) a significant proportion was capable of invasion and limited persistence, and (iii) three more isolates efficiently multiplied within LAMP1-positive vacuoles, one of which was also hyperinvasive. These data identify an intracellular niche for specific A. baumannii clinical isolates that enables extensive multiplication in an environment protected from host immune responses and out of reach of many antibiotics. IMPORTANCE Multidrug-resistant Acinetobacter baumannii isolates are associated with significant morbidity and mortality in hospitals worldwide. Understanding their pathogenicity is critical for improving therapeutic management. Although A. baumannii can steadily adhere to surfaces and host cells, most bacteria remain extracellular. Recent studies have shown that a small proportion of bacteria can invade cells but present limited survival. We have found that some A. baumannii clinical isolates can establish a specialized intracellular niche that sustains extensive intracellular multiplication for a prolonged time without induction of cell death. We propose that this intracellular compartment allows A. baumannii to escape the cell’s normal degradative pathway, protecting bacteria from host immune responses and potentially hindering antibiotic accessibility. This may contribute to A. baumannii persistence, relapsing infections, and enhanced mortality in susceptible patients. A high-content microscopy-based screen confirmed that this pathogenicity trait is present in other clinical A. baumannii isolates. There is an urgent need for new antibiotics or alternative antimicrobial approaches, particularly to combat carbapenem-resistant A. baumannii. The discovery of an intracellular niche for this pathogen, as well as hyperinvasive isolates, may help guide the development of antimicrobial therapies and diagnostics in the future.
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Tiku V. Acinetobacter baumannii: Virulence Strategies and Host Defense Mechanisms. DNA Cell Biol 2022; 41:43-48. [PMID: 34941456 PMCID: PMC8787692 DOI: 10.1089/dna.2021.0588] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 10/17/2021] [Accepted: 11/01/2021] [Indexed: 01/20/2023] Open
Abstract
Acinetobacter baumannii is a highly antibiotic-resistant bacterial pathogen known to cause severe life-threatening infections, including pneumonia, meningitis, and sepsis. Recent emergence of this bacterium as a serious nosocomial pathogen has led to categorization of A. baumannii as a "high-priority" pathogen by the World Health Organization (WHO), for which research efforts are urgently required to develop therapeutic interventions. Some of the properties that make A. baumannii a serious pathogen include its capacity to tolerate high levels of stress and enhanced expression of efflux pumps that enable high degrees of antibiotic resistance. Virulence mechanisms employed by A. baumannii to establish successful infection and host responses elicited against A. baumannii to counter the infection are discussed in detail in this article.
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Affiliation(s)
- Varnesh Tiku
- Vir Biotechnology, San Francisco, California, USA
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