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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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Nasser F, Gaudreau A, Lubega S, Zaker A, Xia X, Mer AS, D'Costa VM. Characterization of the diversity of type IV secretion system-encoding plasmids in Acinetobacter. Emerg Microbes Infect 2024; 13:2320929. [PMID: 38530969 DOI: 10.1080/22221751.2024.2320929] [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: 09/14/2023] [Accepted: 02/14/2024] [Indexed: 03/28/2024]
Abstract
The multi-drug resistant pathogen Acinetobacter baumannii has gained global attention as an important clinical challenge. Owing to its ability to survive on surfaces, its capacity for horizontal gene transfer, and its resistance to front-line antibiotics, A. baumannii has established itself as a successful pathogen. Bacterial conjugation is a central mechanism for pathogen evolution. The epidemic multidrug-resistant A. baumannii ACICU harbours a plasmid encoding a Type IV Secretion System (T4SS) with homology to the E. coli F-plasmid, and plasmids with homologous gene clusters have been identified in several A. baumannii sequence types. However the genetic and host strain diversity, global distribution, and functional ability of this group of plasmids is not fully understood. Using systematic analysis, we show that pACICU2 belongs to a group of almost 120 T4SS-encoding plasmids within four different species of Acinetobacter and one strain of Klebsiella pneumoniae from human and environmental origin, and globally distributed across 20 countries spanning 4 continents. Genetic diversity was observed both outside and within the T4SS-encoding cluster, and 47% of plasmids harboured resistance determinants, with two plasmids harbouring eleven. Conjugation studies with an extensively drug-resistant (XDR) strain showed that the XDR plasmid could be successfully transferred to a more divergent A. baumanii, and transconjugants exhibited the resistance phenotype of the plasmid. Collectively, this demonstrates that these T4SS-encoding plasmids are globally distributed and more widespread among Acinetobacter than previously thought, and that they represent an important potential reservoir for future clinical concern.
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Affiliation(s)
- Farah Nasser
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Avery Gaudreau
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Shareefah Lubega
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
| | - Arvin Zaker
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Xuhua Xia
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
- Department of Biology, University of Ottawa, Ottawa, Canada
| | - Arvind S Mer
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Canada
| | - Vanessa M D'Costa
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
- Centre for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, Canada
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3
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Shields RK, Dorazio AJ, Tiseo G, Squires KM, Leonildi A, Giordano C, Kline EG, Barnini S, Iovleva A, Griffith MP, Van Tyne D, Doi Y, Falcone M. Frequency of cefiderocol heteroresistance among patients treated with cefiderocol for carbapenem-resistant Acinetobacter baumannii infections. JAC Antimicrob Resist 2024; 6:dlae146. [PMID: 39253335 PMCID: PMC11382143 DOI: 10.1093/jacamr/dlae146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Accepted: 08/22/2024] [Indexed: 09/11/2024] Open
Abstract
Background Cefiderocol exhibits potent in vitro activity against carbapenem-resistant Acinetobacter baumannii (CRAb), but this activity has not consistently translated to improved outcomes among patients. Cefiderocol heteroresistance, or the presence of a resistant subpopulation, has been proposed as one possible explanation. The objective of this study was to explore associations between heteroresistance and outcomes of patients with CRAb infections. Methods Baseline CRAb isolates were collected from 27 consecutive patients in the USA and Italy. Cefiderocol susceptibility was tested by broth microdilutions in triplicate. Heteroresistance was defined by population analysis profiling in duplicate. Resistance mechanisms and strain relatedness were evaluated through comparative genomic analysis. Results Overall, 59% of infecting CRAb isolates were identified as cefiderocol-heteroresistant; rates were higher among isolates from Italy (79%) than the USA (38%). The median Charlson Comorbidity and SOFA scores were 4 and 5, respectively; 44% of patients had pneumonia, which was the most common infection type. Rates of 28-day clinical success and survival were 30% and 73%, respectively. By broth microdilution, cefiderocol MICs ≥1 mg/L were associated with higher failure rates than MICs ≤0.5 mg/L (81% versus 55%). Rates of clinical failure were numerically higher among patients infected by cefiderocol-heteroresistant compared with susceptible CRAb (81% versus 55%). Whole-genome sequencing identified a premature stop codon in the TonB-dependent receptor gene piuA in six isolates, all of which were heteroresistant. Conclusions This pilot study supports the hypothesis that cefiderocol treatment failure may be associated with higher MICs and/or the presence of heteroresistance. Further studies are needed to confirm these findings.
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Affiliation(s)
- Ryan K Shields
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Innovative Antimicrobial Therapy, University of Pittsburgh, Pittsburgh, PA, USA
- Antibiotic Management Program, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Ava J Dorazio
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Giusy Tiseo
- Department of Clinical and Experimental Medicine, Azienda Osperdaliero Universitaria Pisana, University of Pisa, Pisa, Italy
| | - Kevin M Squires
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Cesira Giordano
- Microbiology Unit, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy
| | - Ellen G Kline
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Simona Barnini
- Microbiology Unit, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy
| | - Alina Iovleva
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Innovative Antimicrobial Therapy, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Daria Van Tyne
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Innovative Antimicrobial Therapy, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Evolutionary Biology and Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yohei Doi
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Innovative Antimicrobial Therapy, University of Pittsburgh, Pittsburgh, PA, USA
- Departments of Microbiology and Infectious Diseases, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Marco Falcone
- Department of Clinical and Experimental Medicine, Azienda Osperdaliero Universitaria Pisana, University of Pisa, Pisa, Italy
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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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Fardelli E, Di Gioacchino M, Lucidi M, Capecchi G, Bruni F, Sodo A, Visca P, Capellini G. Evidence of Correlation between Membrane Phase Transition and Clonogenicity in Dehydrating Acinetobacter baumannii: A Combined Micro-Raman and AFM Study. J Phys Chem B 2024; 128:6806-6815. [PMID: 38959442 DOI: 10.1021/acs.jpcb.4c01246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The Gram-negative bacterium Acinetobacter baumannii is one of the most resilient multidrug-resistant pathogens in hospitals. Among Gram-negative bacteria, it is particularly resistant to dehydration (anhydrobiosis), and this feature allows A. baumannii to persist in hospital environments for long periods, subjected to unfavorable conditions. We leverage the combination of μ-Raman spectroscopy and atomic force microscopy (AFM) to investigate the anhydrobiotic mechanisms in A. baumannii cells by monitoring the membrane (both inner and outer membranes) properties of four A. baumannii strains during a 16-week dehydration period and in response to temperature excursions. We noted that the membranes of A. baumannii remained intact during the dehydration period despite undergoing a liquid-crystal-to-gel-phase transition, accompanied by changes in the mechanical properties of the membrane. This was evident from the AFM images, which showed the morphology of the bacterial cells alongside modifications of their superficial mechanical properties, and from the alteration in the intensity ratio of μ-Raman features linked to the CH3 and CH2 symmetric stretching modes. Furthermore, employing a universal power law revealed a significant correlation between this ratio and bacterial fitness across all tested strains. Additionally, we subjected dry A. baumannii to a temperature-dependent experiment, the results of which supported the correlation between the Raman ratio and culturability, demonstrating that the phase transition becomes irreversible when A. baumannii cells undergo different temperature cycles. Besides the relevance to the present study, we argue that μ-Raman can be used as a powerful nondestructive tool to assess the health status of bacterial cells based on membrane properties with a relatively high throughput.
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Affiliation(s)
- Elisa Fardelli
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Michael Di Gioacchino
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Massimiliano Lucidi
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
- National Biodiversity Future Center, piazza Marina 61, 90133 Palermo, Italy
| | - Giulia Capecchi
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Fabio Bruni
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Armida Sodo
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Paolo Visca
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
- Fondazione Santa Lucia, Via Ardeatina, 306/354, 00179 Rome, Italy
| | - Giovanni Capellini
- Dipartimento di Scienze, Università degli Studi di Roma Tre, Viale Marconi 446, 00146 Rome, Italy
- IHP Leibniz Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
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Ilyas M, Purkait D, Atmakuri K. Genomic islands and their role in fitness traits of two key sepsis-causing bacterial pathogens. Brief Funct Genomics 2024; 23:55-68. [PMID: 36528816 DOI: 10.1093/bfgp/elac051] [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: 09/13/2022] [Revised: 11/03/2022] [Accepted: 11/11/2022] [Indexed: 01/21/2024] Open
Abstract
To survive and establish a niche for themselves, bacteria constantly evolve. Toward that, they not only insert point mutations and promote illegitimate recombinations within their genomes but also insert pieces of 'foreign' deoxyribonucleic acid, which are commonly referred to as 'genomic islands' (GEIs). The GEIs come in several forms, structures and types, often providing a fitness advantage to the harboring bacterium. In pathogenic bacteria, some GEIs may enhance virulence, thus altering disease burden, morbidity and mortality. Hence, delineating (i) the GEIs framework, (ii) their encoded functions, (iii) the triggers that help them move, (iv) the mechanisms they exploit to move among bacteria and (v) identification of their natural reservoirs will aid in superior tackling of several bacterial diseases, including sepsis. Given the vast array of comparative genomics data, in this short review, we provide an overview of the GEIs, their types and the compositions therein, especially highlighting GEIs harbored by two important pathogens, viz. Acinetobacter baumannii and Klebsiella pneumoniae, which prominently trigger sepsis in low- and middle-income countries. Our efforts help shed some light on the challenges these pathogens pose when equipped with GEIs. We hope that this review will provoke intense research into understanding GEIs, the cues that drive their mobility across bacteria and the ways and means to prevent their transfer, especially across pathogenic bacteria.
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Affiliation(s)
- Mohd Ilyas
- Bacterial Pathogenesis Lab, Infection and Immunity Group, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana 121001, India
| | - Dyuti Purkait
- Bacterial Pathogenesis Lab, Infection and Immunity Group, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana 121001, India
| | - Krishnamohan Atmakuri
- Bacterial Pathogenesis Lab, Infection and Immunity Group, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana 121001, India
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Artuso I, Poddar H, Evans BA, Visca P. Genomics of Acinetobacter baumannii iron uptake. Microb Genom 2023; 9:mgen001080. [PMID: 37549061 PMCID: PMC10483418 DOI: 10.1099/mgen.0.001080] [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: 05/12/2023] [Accepted: 07/10/2023] [Indexed: 08/09/2023] Open
Abstract
Iron is essential for growth in most bacteria due to its redox activity and its role in essential metabolic reactions; it is a cofactor for many bacterial enzymes. The bacterium Acinetobacter baumannii is a multidrug-resistant nosocomial pathogen. A. baumannii responds to low iron availability imposed by the host through the exploitation of multiple iron-acquisition strategies, which are likely to deliver iron to the cell under a variety of environmental conditions, including human and animal infection. To date, six different gene clusters for active iron uptake have been described in A. baumannii , encoding protein systems involved in (i) ferrous iron uptake (feo ); (ii) haem uptake (hemT and hemO ); and (iii) synthesis and transport of the baumannoferrin(s) (bfn ), acinetobactin (bas /bau ) and fimsbactin(s) (fbs ) siderophores. Here we describe the structure, distribution and phylogeny of iron-uptake gene clusters among >1000 genotypically diverse A. baumannii isolates, showing that feo , hemT , bfn and bas /bau clusters are very prevalent across the dataset, whereas the additional haem-uptake system hemO is only present in a portion of the dataset and the fbs gene cluster is very rare. Since the expression of multiple iron-uptake clusters can be linked to virulence, the presence of the additional haem-uptake system hemO may have contributed to the success of some A. baumannii clones.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Harsh Poddar
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Benjamin A. Evans
- Norwich Medical School, University of East Anglia, Rosalind Franklin Road, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
- Fondazione Santa Lucia IRCCS, Via Ardeatina, 306/354, 00179 Rome, Italy
- National Biodiversity Future Centre, Palermo 90133, Italy
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Canciello S, Parisi M, Lucidi M, Visca P, Cincotti G. An image processing-based quantification of gram variability in Acinetobacter baumannii. Microsc Res Tech 2023; 86:378-382. [PMID: 36519728 DOI: 10.1002/jemt.24271] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 11/09/2022] [Accepted: 11/19/2022] [Indexed: 12/16/2022]
Abstract
Gram staining differentiates bacteria as gram-positive and gram-negative, depending on their cell wall constituents, and coloring cells in violet and pink, respectively. Sometimes, a subpopulation of the same bacterial species assumes different colors, ranging from pink to violet, for reasons that are not completely understood yet. We analyze conventional brightfield images and use an automated pipeline to count pink and violet cells. The ImageJ-based processing algorithm quantifies the gram variability in Acinetobacter baumannii ACICU in the stationary phase of growth with a percentage of 66% pink cells. Different bacterial strains and cell growth stages have been considered. RESEARCH HIGHLIGHTS: Gram staining differentiates bacteria into gram-positive (violet) and gram-negative (pink). Gram variability represents an inhomogeneous distribution of pink and violet cells within the same species. We developed an ImageJ-based pipeline for the quantification of Gram variability in Acinetobacter baumannii.
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Affiliation(s)
| | - Miranda Parisi
- Department of Engineering, Roma Tre University, Rome, Italy
| | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy.,Santa Lucia Foundation IRCCS, Rome, Italy
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9
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Traglia GM, Pasteran F, Escalante J, Nishimura B, Tuttobene MR, Subils T, Nuñez MR, Rivollier MG, Corso A, Tolmasky ME, Ramirez MS. Genomic Comparative Analysis of Two Multi-Drug Resistance (MDR) Acinetobacter baumannii Clinical Strains Assigned to International Clonal Lineage II Recovered Pre- and Post-COVID-19 Pandemic. BIOLOGY 2023; 12:358. [PMID: 36979049 PMCID: PMC10045941 DOI: 10.3390/biology12030358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/09/2023] [Accepted: 02/23/2023] [Indexed: 02/26/2023]
Abstract
BACKGROUND After the emergence of COVID-19, numerous cases of A. baumannii/SARS-CoV-2 co-infection were reported. Whether the co-infecting A. baumannii strains have distinctive characteristics remains unknown. METHODS AND RESULTS A. baumannii AMA_NO was isolated in 2021 from a patient with COVID-19. AMA166 was isolated from a mini-BAL used on a patient with pneumonia in 2016. Both genomes were similar, but they possessed 337 (AMA_NO) and 93 (AMA166) unique genes that were associated with biofilm formation, flagellar assembly, antibiotic resistance, secretion systems, and other functions. The antibiotic resistance genes were found within mobile genetic elements. While both strains harbored the carbapenemase-coding gene blaOXA-23, only the strain AMA_NO carried blaNDM-1. Representative functions coded for by virulence genes are the synthesis of the outer core of lipooligosaccharide (OCL5), biosynthesis and export of the capsular polysaccharide (KL2 cluster), high-efficiency iron uptake systems (acinetobactin and baumannoferrin), adherence, and quorum sensing. A comparative phylogenetic analysis including 239 additional sequence type (ST) 2 representative genomes showed high similarity to A. baumannii ABBL141. Since the degree of similarity that was observed between A. baumannii AMA_NO and AMA166 is higher than that found among other ST2 strains, we propose that they derive from a unique background based on core-genome phylogeny and comparative genome analysis. CONCLUSIONS Acquisition or shedding of specific genes could increase the ability of A. baumannii to infect patients with COVID-19.
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Affiliation(s)
- German Matias Traglia
- Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la Republica, Montevideo 11200, Uruguay
| | - Fernando Pasteran
- National Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires 1282, Argentina
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Marisel R. Tuttobene
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario 2000, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario 2000, Argentina
| | - Maria Rosa Nuñez
- Laboratorio de Microbiología, Hospital Provincial Neuquén Dr. Castro Rendón, Neuquén 8300, Argentina
| | | | - Alejandra Corso
- National Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires 1282, Argentina
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Maria Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
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Xu C, Rao J, Xie Y, Lu J, Li Z, Dong C, Wang L, Jiang J, Chen C, Chen S. The DNA Phosphorothioation Restriction-Modification System Influences the Antimicrobial Resistance of Pathogenic Bacteria. Microbiol Spectr 2023; 11:e0350922. [PMID: 36598279 PMCID: PMC9927239 DOI: 10.1128/spectrum.03509-22] [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: 09/04/2022] [Accepted: 11/30/2022] [Indexed: 01/05/2023] Open
Abstract
Bacterial defense barriers, such as DNA methylation-associated restriction-modification (R-M) and the CRISPR-Cas system, play an important role in bacterial antimicrobial resistance (AMR). Recently, a novel R-M system based on DNA phosphorothioate (PT) modification has been shown to be widespread in the kingdom of Bacteria as well as Archaea. However, the potential role of the PT R-M system in bacterial AMR remains unclear. In this study, we explored the role of PT R-Ms in AMR with a series of common clinical pathogenic bacteria. By analyzing the distribution of AMR genes related to mobile genetic elements (MGEs), it was shown that the presence of PT R-M effectively reduced the distribution of horizontal gene transfer (HGT)-derived AMR genes in the genome, even in the bacteria that did not tend to acquire AMR genes by HGT. In addition, unique gene variation analysis based on pangenome analysis and MGE prediction revealed that the presence of PT R-M could suppress HGT frequency. Thus, this is the first report showing that the PT R-M system has the potential to repress HGT-derived AMR gene acquisition by reducing the HGT frequency. IMPORTANCE In this study, we demonstrated the effect of DNA PT modification-based R-M systems on horizontal gene transfer of AMR genes in pathogenic bacteria. We show that there is no apparent association between the genetic background of the strains harboring PT R-Ms and the number of AMR genes or the kinds of gene families. The strains equipped with PT R-M harbor fewer plasmid-derived, prophage-derived, or integrating mobile genetic element (iMGE)-related AMR genes and have a lower HGT frequency, but the degree of inhibition varies among different bacteria. In addition, compared with Salmonella enterica and Escherichia coli, Klebsiella pneumoniae prefers to acquire MGE-derived AMR genes, and there is no coevolution between PT R-M clusters and bacterial core genes.
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Affiliation(s)
- Congrui Xu
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Jing Rao
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Yuqing Xie
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Jiajun Lu
- Information Engineering Institute, Wuchang Institute of Technology, Wuhan, China
| | - Zhiqiang Li
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Changjiang Dong
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Lianrong Wang
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
| | - Jinghong Jiang
- Department of Obstetrics & Gynecology, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Chao Chen
- Department of Burn and Plastic Surgery, Shenzhen Institute of Translational Medicine, Health Science Center, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Shi Chen
- Brain Center, Department of Neurosurgery, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China
- Department of Burn and Plastic Surgery, Shenzhen Institute of Translational Medicine, Health Science Center, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
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11
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Li P, Zhang S, Wang J, Al-Shamiri MM, Han B, Chen Y, Han S, Han L. Uncovering the Secretion Systems of Acinetobacter baumannii: Structures and Functions in Pathogenicity and Antibiotic Resistance. Antibiotics (Basel) 2023; 12:antibiotics12020195. [PMID: 36830106 PMCID: PMC9952577 DOI: 10.3390/antibiotics12020195] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Infections led by Acinetobacter baumannii strains are of great concern in healthcare environments due to the strong ability of the bacteria to spread through different apparatuses and develop drug resistance. Severe diseases can be caused by A. baumannii in critically ill patients, but its biological process and mechanism are not well understood. Secretion systems have recently been demonstrated to be involved in the pathogenic process, and five types of secretion systems out of the currently known six from Gram-negative bacteria have been found in A. baumannii. They can promote the fitness and pathogenesis of the bacteria by releasing a variety of effectors. Additionally, antibiotic resistance is found to be related to some types of secretion systems. In this review, we describe the genetic and structural compositions of the five secretion systems that exist in Acinetobacter. In addition, the function and molecular mechanism of each secretion system are summarized to explain how they enable these critical pathogens to overcome eukaryotic hosts and prokaryotic competitors to cause diseases.
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Affiliation(s)
- Pu Li
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Sirui Zhang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Jingdan Wang
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Mona Mohamed Al-Shamiri
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Bei Han
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Yanjiong Chen
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Shaoshan Han
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710061, China
| | - Lei Han
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
- Correspondence:
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12
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Fardelli E, Lucidi M, Di Gioacchino M, Bashiri S, Persichetti L, Capecchi G, Gasperi T, Sodo A, Visca P, Capellini G. Bio-physical mechanisms of dehydrating membranes of Acinetobacter baumannii linked to drought-resistance. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184045. [PMID: 36108779 DOI: 10.1016/j.bbamem.2022.184045] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/29/2022] [Accepted: 09/05/2022] [Indexed: 06/15/2023]
Abstract
Acinetobacter baumanni, is an opportunistic nosocomial multi-drug resistant bacterium, which represents a threat for human health. This pathogen is able to persist in intensive care units thanks to its extraordinary resistance towards dehydration, whose mechanisms are unknown and enable it to easily spread through surfaces, contaminating also medical devices. In this article we reveal, with a multimodal approach, based on μ-R Spectroscopy, Gas Chromatography coupled to Mass Spectroscopy, Atomic Force Microscopy and Fluorescence Recovery After Photobleaching, the bio-physical mechanisms that the membrane of two A. baumannii strains undergoes during dehydration. Showing a substantial decoupling of the phase transition from liquid crystalline to gel phase from evidence of cell lysis. Such decoupling may be the core of the resistance of A. baumannii against dehydration and highlights the different ability to resist to drought between strains.
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Affiliation(s)
- Elisa Fardelli
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy.
| | - Massimiliano Lucidi
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy
| | - Michael Di Gioacchino
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy
| | - Shadi Bashiri
- CNR, NEST, Istituto Nanoscienze, P.zza S. Silvestro, 12, Pisa, 56127, Italy
| | - Luca Persichetti
- University of Tor Vergata, Department of physics, Via della Ricerca Scientifica, 1, Rome, 00133, Italy
| | - Giulia Capecchi
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy
| | - Tecla Gasperi
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy; National Institute of Biostructures and Biosystems (INBB), Viale delle Medaglie d'Oro, 305, Rome, 00136, Italy
| | - Armida Sodo
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy
| | - Paolo Visca
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy; Santa Lucia Foundation IRCCS, Via Ardeatina, 306/354, Rome, 00179, Italy
| | - Giovanni Capellini
- University of Roma Tre, Department of Science, Viale G. Marconi, 446, Rome, 00146, Italy
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13
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Segatore B, Piccirilli A, Cherubini S, Principe L, Alloggia G, Mezzatesta ML, Salmeri M, Di Bella S, Migliavacca R, Piazza A, Meroni E, Fazii P, Visaggio D, Visca P, Cortazzo V, De Angelis G, Pompilio A, Perilli M. In Vitro Activity of Sulbactam-Durlobactam against Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates: A Multicentre Report from Italy. Antibiotics (Basel) 2022; 11:antibiotics11081136. [PMID: 36010006 PMCID: PMC9404735 DOI: 10.3390/antibiotics11081136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/18/2022] [Accepted: 08/19/2022] [Indexed: 11/16/2022] Open
Abstract
In the present study, the in vitro activity of the sulbactam-durlobactam (SUL-DUR) combination was evaluated against 141 carbapenem-resistant A. baumannii (CRAb) clinical strains collected from six Italian laboratories. Over half (54.6%) of these isolates were resistant to colistin. The SUL-DUR combination was active against these CRAb isolates with MIC50 and MIC90 values of 0.5 mg/L and 4 mg/L, respectively. Only eleven isolates were resistant to SUL-DUR with MIC values ranging from 8 to 128 mg/L. The SUL-DUR resistant A. baumannii exhibited several antimicrobial resistance genes (ARGs) such as blaOXA-20, blaOXA-58, blaOXA-66, blaADC-25, aac(6')-Ib3 and aac(6')-Ib-cr and mutations in gyrA (S81L) and parC (V104I, D105E). However, in these isolates, mutations Q488K and Y528H were found in PBP3. Different determinants were also identified in these CRAb isolates, including adeABC, adeFGH, adeIJK, abeS, abaQ and abaR, which encode multidrug efflux pumps associated with resistance to multiple antibacterial agents. This is the first report on the antimicrobial activity of SUL-DUR against carbapenem-resistant A. baumannii isolates selected from multiple regions in Italy.
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Affiliation(s)
- Bernardetta Segatore
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Alessandra Piccirilli
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Sabrina Cherubini
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Luigi Principe
- Clinical Pathology and Microbiology Unit, “S. Giovanni di Dio” Hospital, 88900 Crotone, Italy
- Correspondence:
| | - Giovanni Alloggia
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Maria Lina Mezzatesta
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, 95131 Catania, Italy
| | - Mario Salmeri
- Department of Biomedical and Biotechnological Sciences, Section of Microbiology, University of Catania, 95131 Catania, Italy
| | - Stefano Di Bella
- Clinical Department of Medical, Surgical and Health Sciences, University of Trieste, 34129 Trieste, Italy
| | - Roberta Migliavacca
- Unit of Microbiology and Clinical Microbiology, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
| | - Aurora Piazza
- Unit of Microbiology and Clinical Microbiology, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
| | - Elisa Meroni
- Clinical Microbiology and Virology Unit, “A. Manzoni” Hospital, 23900 Lecco, Italy
| | - Paolo Fazii
- Clinical Microbiology and Virology Unit, Spirito Santo Hospital, 65122 Pescara, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
- Santa Lucia Foundation IRCCS, 00179 Rome, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
- Santa Lucia Foundation IRCCS, 00179 Rome, Italy
| | - Venere Cortazzo
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Giulia De Angelis
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Arianna Pompilio
- Department of Medical, Oral and Biotechnological Sciences, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy
- Center of Advanced Studies and Technology (CAST), “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy
| | - Mariagrazia Perilli
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
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Camargo CH, Yamada AY, Nagamori FO, de Souza AR, Tiba-Casas MR, de Moraes França FA, Porto MHTN, de Lima Garzon ML, Higgins P, Madalosso G, de Assis DB. Clonal spread of ArmA- and OXA-23-coproducing Acinetobacter baumannii International Clone 2 in Brazil during the first wave of the COVID-19 pandemic. J Med Microbiol 2022; 71. [PMID: 35417321 DOI: 10.1099/jmm.0.001509] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Introduction. Carbapenem-resistant Acinetobacter baumannii (CRAB) is the primary pathogen causing hospital-acquired infections. The spread of CRAB is mainly driven by the dissemination of resistant clones, and in Latin America, International Clones IC-1 (also known as clonal complex CC1), IC-4 (CC15) and IC-5 (CC79) are the most prevalent.Gap Statement. There are no documented outbreaks of CRAB International Clone 2 (IC-2) reported in Brazil.Aim. To describe a large outbreak of CRAB caused by the uncommon IC-2 in a Brazilian COVID-19 hospital.Methodology. From May 2020 to May 2021, 224 patients infected or colonized with CRAB were identified in a single hospital; 92 % of them were also infected with SARS-CoV-2. From these patients, 137 isolates were recovered and subjected to antimicrobial susceptibility testing, PCR analysis and molecular typing. Whole-genome sequencing and downstream analysis were carried out on a representative isolate (the first available isolate).Results. In 76 % of the patients, a single OXA-23-producing CRAB IC-2 was identified. All the isolates were susceptible to polymyxin B, but highly resistant (>95 %) to aminoglycosides, fluoroquinolones and beta-lactams. Genomic analysis revealed that the representative isolate also carried the 16S rRNA Methylase ArmA, which was detected for the first time in this species in Brazil.Conclusion. We report the rapid spread of an emerging CRAB clone responsible for causing a large outbreak in a hospital in Brazil, a country with predominance of other CRAB clones. Continuous and prospective surveillance is warranted to evaluate the impact of this clone in Brazilian hospital settings.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Paul Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Partner site Bonn-Cologne, Cologne, Germany
| | - Geraldine Madalosso
- Divisão de Infecção Hospitalar, Centro de Vigilância Epidemiológica, São Paulo, Brazil
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Dong JF, Feng CJ, Wang P, Li RQ, Zou QH. Comparative genomics analysis of Acinetobacter baumannii multi-drug resistant and drug sensitive strains in China. Microb Pathog 2022; 165:105492. [DOI: 10.1016/j.micpath.2022.105492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/28/2022] [Accepted: 03/15/2022] [Indexed: 10/18/2022]
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16
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Jones NI, Harmer CJ, Hamidian M, Hall RM. Evolution of Acinetobacter baumannii plasmids carrying the oxa58 carbapenemase resistance gene via plasmid fusion, IS26-mediated events and dif module shuffling. Plasmid 2022; 121:102628. [DOI: 10.1016/j.plasmid.2022.102628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 10/18/2022]
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Abstract
Acinetobacter baumannii is an important hospital-associated pathogen that causes antibiotic resistant infections and reoccurring hospital outbreaks. A. baumannii’s ability to asymptomatically colonize patients is a risk factor for infection and exacerbates its spread. However, there is little information describing the mechanisms it employs to colonize patients. A. baumannii often colonizes the upper respiratory tract and skin. Antibiotic use is a risk factor for colonization and infection suggesting that A. baumannii likely competes with commensal bacteria to establish a niche. To begin to investigate this possibility, we cocultured A. baumannii and commensal bacteria of the upper respiratory tract and skin. In conditions that mimic iron starvation experienced in the host, we observed that A. baumannii inhibits Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus haemolyticus and Corynebacterium striatum. Then using an ordered transposon library screen we identified the A. baumannii siderophore acinetobactin as the causative agent of the inhibition phenotype. Using mass spectrometry, we show that acinetobactin is released from A. baumannii under our coculture conditions and that purified acinetobactin can inhibit C. striatum and S. hominis. Together our data suggest that acinetobactin may provide a competitive advantage for A. baumannii over some respiratory track and skin commensal bacteria and possibly support its ability to colonize patients. IMPORTANCE The ability of Acinetobacter baumannii to asymptomatically colonize patients is a risk factor for infection and exacerbates its clinical spread. However, there is minimal information describing how A. baumannii asymptomatically colonizes patients. Here we provide evidence that A. baumannii can inhibit the growth of many skin and upper respiratory commensal bacteria through iron competition and identify acinetobactin as the molecule supporting its nutritional advantage. Outcompeting endogenous commensals through iron competition may support the ability of A. baumannii to colonize and spread among patients.
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18
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Migliaccio A, Esposito EP, Bagattini M, Berisio R, Triassi M, De Gregorio E, Zarrilli R. Inhibition of AdeB, AceI, and AmvA Efflux Pumps Restores Chlorhexidine and Benzalkonium Susceptibility in Acinetobacter baumannii ATCC 19606. Front Microbiol 2022; 12:790263. [PMID: 35197939 PMCID: PMC8859242 DOI: 10.3389/fmicb.2021.790263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/23/2021] [Indexed: 01/17/2023] Open
Abstract
The management of infections caused by Acinetobacter baumannii is hindered by its intrinsic tolerance to a wide variety of biocides. The aim of the study was to analyze the role of different A. baumannii efflux pumps (EPs) in tolerance to chlorhexidine (CHX) and benzalkonium (BZK) and identify non-toxic compounds, which can restore susceptibility to CHX and BZK in A. baumannii. A. baumannii ATCC 19606 strain was tolerant to both CHX and BZK with MIC and MBC value of 32 mg/L. CHX subMIC concentrations increased the expression of adeB and adeJ (RND superfamily), aceI (PACE family) and amvA (MFS superfamily) EP genes. The values of CHX MIC and MBC decreased by eightfold in ΔadeB and twofold in ΔamvA or ΔaceI mutants, respectively, while not affected in ΔadeJ mutant; EPs double and triple deletion mutants showed an additive effect on CHX MIC. CHX susceptibility was restored in double and triple deletion mutants with inactivation of adeB gene. BZK MIC was decreased by fourfold in ΔadeB mutant, and twofold in ΔamvA and ΔaceI mutants, respectively; EPs double and triple deletion mutants showed an additive effect on BZK MIC. BZK susceptibility was recovered in ΔadeB ΔaceI ΔadeJ and ΔamvA ΔadeB ΔadeJ triple mutants. The structural comparison of AdeB and AdeJ protomers showed a more negatively charged entrance binding site and F-loop in AdeB, which may favor the transport of CHX. The carbonyl cyanide m-chlorophenylhydrazine protonophore (CCCP) EP inhibitor reduced dose-dependently CHX MIC in A. baumannii ATCC 19606 and in ΔadeJ, ΔaceI, or ΔamvA mutants, but not in ΔadeB mutant. Either piperine (PIP) or resveratrol (RV) at non-toxic concentrations inhibited CHX MIC in A. baumannii ATCC 19606 parental strain and EPs gene deletion mutants, and CHX-induced EP gene expression. Also, RV inhibited BZK MIC and EP genes expression in A. baumannii ATCC 19606 parental strain and EPs mutants. These results demonstrate that tolerance to CHX and BZK in A. baumannii is mediated by the activation of AdeB, AceI and AmvA EPs, AdeB playing a major role. Importantly, inhibition of EP genes expression by RV restores CHX and BZK susceptibility in A. baumannii.
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Affiliation(s)
| | - Eliana Pia Esposito
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Maria Bagattini
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Rita Berisio
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Maria Triassi
- Department of Public Health, University of Naples Federico II, Naples, Italy
| | - Eliana De Gregorio
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
- *Correspondence: Eliana De Gregorio,
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
- Raffaele Zarrilli,
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19
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Artuso I, Lucidi M, Visaggio D, Capecchi G, Lugli GA, Ventura M, Visca P. Genome diversity of domesticated Acinetobacter baumannii ATCC 19606 T strains. Microb Genom 2022; 8. [PMID: 35084299 PMCID: PMC8914354 DOI: 10.1099/mgen.0.000749] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii has emerged as an important opportunistic pathogen worldwide, being responsible for large outbreaks for nosocomial infections, primarily in intensive care units. A. baumannii ATCC 19606T is the species type strain, and a reference organism in many laboratories due to its low virulence, amenability to genetic manipulation and extensive antibiotic susceptibility. We wondered if frequent propagation of A. baumannii ATCC 19606T in different laboratories may have driven micro- and macro-evolutionary events that could determine inter-laboratory differences of genome-based data. By combining Illumina MiSeq, MinION and Sanger technologies, we generated a high-quality whole-genome sequence of A. baumannii ATCC 19606T, then performed a comparative genome analysis between A. baumannii ATCC 19606T strains from several research laboratories and a reference collection. Differences between publicly available ATCC 19606T genome sequences were observed, including SNPs, macro- and micro-deletions, and the uneven presence of a 52 kb prophage belonging to genus Vieuvirus. Two plasmids, pMAC and p1ATCC19606, were invariably detected in all tested strains. The presence of a putative replicase, a replication origin containing four 22-mer direct repeats, and a toxin-antitoxin system implicated in plasmid stability were predicted by in silico analysis of p1ATCC19606, and experimentally confirmed. This work refines the sequence, structure and functional annotation of the A. baumannii ATCC 19606T genome, and highlights some remarkable differences between domesticated strains, likely resulting from genetic drift.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Massimiliano Lucidi
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy.,Santa Lucia Fundation IRCCS, Via Ardeatina 306-354, 00179 Rome, Italy
| | - Giulia Capecchi
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Gabriele Andrea Lugli
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Marco Ventura
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy.,Santa Lucia Fundation IRCCS, Via Ardeatina 306-354, 00179 Rome, Italy
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20
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Interbacterial Transfer of Carbapenem Resistance and Large Antibiotic Resistance Islands by Natural Transformation in Pathogenic Acinetobacter. mBio 2022; 13:e0263121. [PMID: 35073754 PMCID: PMC8787482 DOI: 10.1128/mbio.02631-21] [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: 12/22/2022] Open
Abstract
Acinetobacter baumannii infection poses a major health threat, with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intrastrain but also interstrain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4 and AbaR1) than when the same bacteria are supplied with large amounts of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genomes of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombinants and results from both spontaneous release and interbacterial predatory behavior. In the light of our results, natural transformation should be considered a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii.
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Characterization of Amino Acid Substitutions in the Two-Component Regulatory System AdeRS Identified in Multidrug-Resistant Acinetobacter baumannii. mSphere 2021; 6:e0070921. [PMID: 34817237 PMCID: PMC8612257 DOI: 10.1128/msphere.00709-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Acinetobacter baumannii, resistance-nodulation-cell division (RND)-type efflux is a resistance mechanism of great importance since it contributes to reduced susceptibility to multiple antimicrobial compounds. Some mutations within the genes encoding the two-component regulatory system AdeRS appear to play a major role in increased expression of the RND efflux pump AdeABC and, consequently, in reduced antimicrobial susceptibility, as they are commonly observed in multidrug-resistant (MDR) A. baumannii. In the present study, the impact of frequently identified amino acid substitutions, namely, D21V and D26N in AdeR and T156M in AdeS, on adeB expression, efflux activity, and antimicrobial susceptibility was investigated. Reverse transcription-quantitative PCR (qRT-PCR) studies revealed significantly increased adeB expression caused by D26N (AdeR) and T156M (AdeS). In addition, accumulation assays have shown that these mutations induce increased efflux activity. Subsequently, antimicrobial susceptibility testing via agar dilution and broth microdilution confirmed the importance of these substitutions for the MDR phenotype, as the MICs for various antimicrobials of different classes were increased. In contrast, the amino acid substitution D21V in AdeR did not lead to increased adeB expression and did not reduce antimicrobial susceptibility. This study demonstrates the impact of the D26N (AdeR) and T156M (AdeS) amino acid substitutions, highlighting that these regulators represent promising targets for interfering with efflux activity to restore antimicrobial susceptibility. IMPORTANCE The active efflux of antimicrobials by bacteria can lead to antimicrobial resistance and persistence and can affect multiple different classes of antimicrobials. Efflux pumps are tightly regulated, and their overexpression can be mediated by changes in their regulators. Identifying these changes is one step in the direction of resistance prediction, but it also opens the possibility of targeting efflux pump regulation as a strategy to overcome antimicrobial resistance. Here, we have investigated commonly found changes in the regulators of the main efflux pumps in Acinetobacter baumannii.
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Abstract
Infection by multidrug-resistant (MDR) Acinetobacter baumannii is one of the major causes of hospital-acquired infections worldwide. The ability of A. baumannii to survive in adverse conditions as well as its extensive antimicrobial resistance make it one of the most difficult to treat pathogens associated with high mortality rates. The aim of this study was to investigate MDR A. baumannii that has spread among pediatric cancer patients in the Children’s Cancer Hospital Egypt 57357. Whole-genome sequencing was used to characterize 31 MDR A. baumannii clinical isolates. Phenotypically, the isolates were MDR, with four isolates showing resistance to the last-resort antibiotic colistin. Multilocus sequence typing showed the presence of eight clonal groups, two of which were previously reported to cause outbreaks in Egypt, and one novel sequence type (ST), Oxf-ST2246. Identification of the circulating plasmids showed the presence of two plasmid lineages in the isolates, strongly governed by sequence type. A large number of antimicrobial genes with a range of resistance mechanisms were detected in the isolates, including β-lactamases and antibiotic efflux pumps. Analysis of insertion sequences (ISs) revealed the presence of ISAba1 and ISAba125 in all the samples, which amplify β-lactamase expression, causing extensive carbapenem resistance. Mutation analysis was used to decipher underlying mutations responsible for colistin resistance and revealed novel mutations in several outer membrane proteins, in addition to previously reported mutations in pmrB. Altogether, understanding the transmissibility of A. baumannii as well as its resistance and virulence mechanisms will help develop novel treatment options for better management of hospital-acquired infections. IMPORTANCEAcinetobacter baumannii represents a major health threat, in particular among immunocompromised cancer patients. The rise in carbapenem-resistant A. baumannii, and the development of resistance to the last-resort antimicrobial agent colistin, complicates the management of A. baumannii outbreaks and increases mortality rates. Here, we investigate 31 multidrug resistant A. baumannii isolates from pediatric cancer patients in Children’s Cancer Hospital Egypt (CCHE) 57357 via whole-genome sequencing. Multilocus sequence typing (MLST) showed the presence of eight clonal groups including a novel sequence type. In silico detection of antimicrobial-resistant genes and virulence factors revealed a strong correlation between certain virulence genes and mortality as well as several point mutations in outer membrane proteins contributing to colistin resistance. Detection of CRISPR/Cas sequences in the majority of the samples was strongly correlated with the presence of prophage sequences and associated with failure of bacteriophage therapy. Altogether, understanding the genetic makeup of circulating A. baumannii is essential for better management of outbreaks.
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Conde-Pérez K, Vázquez-Ucha JC, Álvarez-Fraga L, Ageitos L, Rumbo-Feal S, Martínez-Guitián M, Trigo-Tasende N, Rodríguez J, Bou G, Jiménez C, Beceiro A, Poza M. In-Depth Analysis of the Role of the Acinetobactin Cluster in the Virulence of Acinetobacter baumannii. Front Microbiol 2021; 12:752070. [PMID: 34675911 PMCID: PMC8524058 DOI: 10.3389/fmicb.2021.752070] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is a multidrug-resistant pathogen that represents a serious threat to global health. A. baumannii possesses a wide range of virulence factors that contribute to the bacterial pathogenicity. Among them, the siderophore acinetobactin is one of the most important, being essential for the development of the infection. In this study we performed an in-depth analysis of the acinetobactin cluster in the strain A. baumannii ATCC 17978. For this purpose, nineteen individual isogenic mutant strains were generated, and further phenotypical analysis were performed. Individual mutants lacking the biosynthetic genes entA, basG, basC, basD, and basB showed a significant loss in virulence, due to the disruption in the acinetobactin production. Similarly, the gene bauA, coding for the acinetobactin receptor, was also found to be crucial for the bacterial pathogenesis. In addition, the analysis of the ΔbasJ/ΔfbsB double mutant strain demonstrated the high level of genetic redundancy between siderophores where the role of specific genes of the acinetobactin cluster can be fulfilled by their fimsbactin redundant genes. Overall, this study highlights the essential role of entA, basG, basC, basD, basB and bauA in the pathogenicity of A. baumannii and provides potential therapeutic targets for the design of new antivirulence agents against this microorganism.
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Affiliation(s)
- Kelly Conde-Pérez
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
| | - Juan C Vázquez-Ucha
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Laura Álvarez-Fraga
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia
| | - Lucía Ageitos
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Soraya Rumbo-Feal
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
| | - Marta Martínez-Guitián
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Noelia Trigo-Tasende
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Jaime Rodríguez
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Germán Bou
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Carlos Jiménez
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Alejandro Beceiro
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Margarita Poza
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
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24
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Recombinant Production and Characterization of an Extracellular Subtilisin-Like Serine Protease from Acinetobacter baumannii of Fermented Food Origin. Protein J 2021; 40:419-435. [PMID: 33870461 PMCID: PMC8053418 DOI: 10.1007/s10930-021-09986-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2021] [Indexed: 12/20/2022]
Abstract
Acinetobacter baumannii is a ubiquitous bacteria that is increasingly becoming a formidable nosocomial pathogen. Due to its clinical relevance, studies on the bacteria's secretory molecules especially extracellular proteases are of interest primarily in relation to the enzyme's role in virulence. Besides, favorable properties that extracellular proteases possess may be exploited for commercial use thus there is a need to investigate extracellular proteases from Acinetobacter baumannii to gain insights into their catalytic properties. In this study, an extracellular subtilisin-like serine protease from Acinetobacter baumannii designated as SPSFQ that was isolated from fermented food was recombinantly expressed and characterized. The mature catalytically active form of SPSFQ shared a high percentage sequence identity of 99% to extracellular proteases from clinical isolates of Acinetobacter baumannii and Klebsiella pneumoniae as well as a moderately high percentage identity to other bacterial proteases with known keratinolytic and collagenolytic activity. The homology model of mature SPSFQ revealed its structure is composed of 10 β-strands, 8 α-helices, and connecting loops resembling a typical architecture of subtilisin-like α/β motif. SPSFQ is catalytically active at an optimum temperature of 40 °C and pH 9. Its activity is stimulated in the presence of Ca2+ and severely inhibited in the presence of PMSF. SPSFQ also displayed the ability to degrade several tissue-associated protein substrates such as keratin, collagen, and fibrin. Accordingly, our study shed light on the catalytic properties of a previously uncharacterized extracellular serine protease from Acinetobacter baumannii that warrants further investigations into its potential role as a virulence factor in pathogenicity and commercial applications.
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25
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Verma P, Tiwari M, Tiwari V. Efflux pumps in multidrug-resistant Acinetobacter baumannii: Current status and challenges in the discovery of efflux pumps inhibitors. Microb Pathog 2021; 152:104766. [PMID: 33545327 DOI: 10.1016/j.micpath.2021.104766] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/13/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
Acinetobacter baumannii is an ESKAPE pathogen known to cause fatal nosocomial infections. With the surge of multidrug resistance (MDR) in the bacterial system, effective treatment measures have become very limited. The MDR in A. baumannii is contributed by various factors out of which efflux pumps have gained major attention due to their broad substrate specificity and wide distribution among bacterial species. The efflux pumps are involved in the MDR as well as contribute to other physiological processes in bacteria, therefore, it is critically important to inhibit efflux pumps in order to combat emerging resistance. The present review provides insight about the different efflux pump systems in A. baumannii and their role in multidrug resistance. A major focus has been put on the different strategies and alternate therapeutics to inhibit the efflux system. This includes use of different efflux pump inhibitors-natural, synthetic or combinatorial therapy. The use of phage therapy and nanoparticles for inhibiting efflux pumps have also been discussed here. Moreover, the present review provides the knowledge of barriers in development of efflux pump inhibitors (EPIs) and their approval for commercialization. Here, different prospectives have been discussed to improve the therapeutic development process and make it more compatible for clinical use.
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Affiliation(s)
- Privita Verma
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Monalisa Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India
| | - Vishvanath Tiwari
- Department of Biochemistry, Central University of Rajasthan, Bandarsindri, Ajmer, 305817, India.
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26
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Bashiri S, Lucidi M, Visaggio D, Capecchi G, Persichetti L, Cincotti G, Visca P, Capellini G. Growth Phase- and Desiccation-Dependent Acinetobacter baumannii Morphology: An Atomic Force Microscopy Investigation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1110-1119. [PMID: 33433226 DOI: 10.1021/acs.langmuir.0c02980] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Acinetobacter baumannii has emerged as a major bacterial pathogen during the past three decades. The majority of the A. baumannii infections occur in hospitals and are caused by strains endowed with high desiccation tolerance, which represents an essential feature for the adaptation to the nosocomial environment. This work aims at investigating the desiccation response of the multidrug-resistant A. baumannii strain ACICU as a function of the bacterial growth phase and oxygen availability, by correlating bacterial survival with shape alterations. The three-dimensional morphological analysis of bacteria was carried out by atomic force microscopy (AFM), following the evolution of bacterial shape descriptors, such as the area, volume, roughness of individual cell membranes, and the cell cluster roughness, which exhibited peculiar and distinctive behavior as a function of the growth conditions. AFM images of A. baumannii ACICU cells revealed the prevalence of the coccoid morphology at all growth stages, with a tendency to reduce their size in the stationary phase, accompanied by a higher survival rate to air-drying. Moreover, cells harvested from the logarithmic phase featured a larger volume and resulted to be more sensitive to desiccation compared to the cells harvested at later growth stages. In addition, oxygen deprivation caused a significant decrease in cellular size and was associated with the formation of pores in the cell membrane, accompanied by a relative reduction in culturability after desiccation. Morphological plasticity and multidrug resistance may contribute to desiccation tolerance and therefore to persistence in the hospital setting.
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Affiliation(s)
- Shadi Bashiri
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
| | - Massimiliano Lucidi
- Department of Engineering, University Roma Tre, via Vito Volterra 62, 00146 Rome, Italy
| | - Daniela Visaggio
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
| | - Giulia Capecchi
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
| | - Luca Persichetti
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
| | - Gabriella Cincotti
- Department of Engineering, University Roma Tre, via Vito Volterra 62, 00146 Rome, Italy
| | - Paolo Visca
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
| | - Giovanni Capellini
- Department of Science, University Roma Tre, viale Guglielmo Marconi 446, 00146 Rome, Italy
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27
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Sykes EME, Deo S, Kumar A. Recent Advances in Genetic Tools for Acinetobacter baumannii. Front Genet 2020; 11:601380. [PMID: 33414809 PMCID: PMC7783400 DOI: 10.3389/fgene.2020.601380] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/30/2020] [Indexed: 12/26/2022] Open
Abstract
Acinetobacter baumannii is classified as a top priority pathogen by the World Health Organization (WHO) because of its widespread resistance to all classes of antibiotics. This makes the need for understanding the mechanisms of resistance and virulence critical. Therefore, tools that allow genetic manipulations are vital to unravel the mechanisms of multidrug resistance (MDR) and virulence in A. baumannii. A host of current strategies are available for genetic manipulations of A. baumannii laboratory-strains, including ATCC® 17978TM and ATCC® 19606T, but depending on susceptibility profiles, these strategies may not be sufficient when targeting strains newly obtained from clinic, primarily due to the latter's high resistance to antibiotics that are commonly used for selection during genetic manipulations. This review highlights the most recent methods for genetic manipulation of A. baumannii including CRISPR based approaches, transposon mutagenesis, homologous recombination strategies, reporter systems and complementation techniques with the spotlight on those that can be applied to MDR clinical isolates.
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Affiliation(s)
| | | | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
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28
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CsrA Supports both Environmental Persistence and Host-Associated Growth of Acinetobacter baumannii. Infect Immun 2020; 88:IAI.00259-20. [PMID: 32989034 DOI: 10.1128/iai.00259-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/18/2020] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic and frequently multidrug-resistant Gram-negative bacterial pathogen that primarily infects critically ill individuals. Indirect transmission from patient to patient in hospitals can drive infections, supported by this organism's abilities to persist on dry surfaces and rapidly colonize susceptible individuals. To investigate how A. baumannii survives on surfaces, we cultured A. baumannii in liquid media for several days and then analyzed isolates that lost the ability to survive drying. One of these isolates carried a mutation that affected the gene encoding the carbon storage regulator CsrA. As we began to examine the role of CsrA in A. baumannii, we observed that the growth of ΔcsrA mutant strains was inhibited in the presence of amino acids. The ΔcsrA mutant strains had a reduced ability to survive drying and to form biofilms but an improved ability to tolerate increased osmolarity compared with the wild type. We also examined the importance of CsrA for A. baumannii virulence. The ΔcsrA mutant strains had a greatly reduced ability to kill Galleria mellonella larvae, could not replicate in G. mellonella hemolymph, and also had a growth defect in human serum. Together, these results show that CsrA is essential for the growth of A. baumannii on host-derived substrates and is involved in desiccation tolerance, implying that CsrA controls key functions involved in the transmission of A. baumannii in hospitals.
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29
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Zong G, Zhong C, Fu J, Zhang Y, Zhang P, Zhang W, Xu Y, Cao G, Zhang R. The carbapenem resistance gene bla OXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19. Antimicrob Resist Infect Control 2020; 9:182. [PMID: 33168102 PMCID: PMC7653874 DOI: 10.1186/s13756-020-00832-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/16/2020] [Indexed: 12/18/2022] Open
Abstract
Background Carbapenem resistant Acinetobacter species have caused great difficulties in clinical therapy in the worldwide. Here we describe an Acinetobacter johnsonii M19 with a novel blaOXA-23 containing transposon Tn6681 on the conjugative plasmid pFM-M19 and the ability to transferand carbapenem resistance.
Methods A. johnsonii M19 was isolated under selection with 8 mg/L meropenem from hospital sewage, and the minimum inhibitory concentrations (MICs) for the representative carbapenems imipenem, meropenem and ertapenem were determined. The genome of A. johnsonii M19 was sequenced by PacBio RS II and Illumina HiSeq 4000 platforms. A homologous model of OXA-23 was generated, and molecular docking models with imipenem, meropenem and ertapenem were constructed by Discovery Studio 2.0. Type IV secretion system and conjugation elements were identified by the Pathosystems Resource Integration Center (PATRIC) server and the oriTfinder. Mating experiments were performed to evaluate transfer of OXA-23 to Escherichia coli 25DN. Results MICs of A. johnsonii M19 for imipenem, meropenem and ertapenem were 128 mg/L, 48 mg/L and 24 mg/L, respectively. Genome sequencing identified plasmid pFM-M19, which harbours the carbapenem resistance gene blaOXA-23 within the novel transposon Tn6681. Molecular docking analysis indicated that the elongated hydrophobic tunnel of OXA-23 provides a hydrophobic environment and that Lys-216, Thr-217, Met-221 and Arg-259 were the conserved amino acids bound to imipenem, meropenem and ertapenem. Furthermore, pFM-M19 could transfer blaOXA-23 to E. coli 25DN by conjugation, resulting in carbapenem-resistant transconjugants.
Conclusions Our investigation showed that A. johnsonii M19 is a source and disseminator of blaOXA-23 and carbapenem resistance. The ability to transfer blaOXA-23 to other species by the conjugative plasmid pFM-M19 raises the risk of spread of carbapenem resistance. Graphic abstract The carbapenem resistance gene blaOXA-23 is disseminated by a conjugative plasmid containing the novel transposon Tn6681 in Acinetobacter johnsonii M19.![]()
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Affiliation(s)
- Gongli Zong
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, China.,Department of Epidemiology, The First Affiliated Hospital of Shandong First Medical University, Jinan, 250062, China.,Shandong Medicinal Biotechnology Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250062, China
| | - Chuanqing Zhong
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China
| | - Jiafang Fu
- Department of Epidemiology, The First Affiliated Hospital of Shandong First Medical University, Jinan, 250062, China.,Shandong Medicinal Biotechnology Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250062, China.,Key Lab for Biotech-Drugs of National Health Commission, Jinan, 250062, China
| | - Yu Zhang
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China
| | - Peipei Zhang
- Department of Epidemiology, The First Affiliated Hospital of Shandong First Medical University, Jinan, 250062, China.,Shandong Medicinal Biotechnology Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250062, China.,Key Lab for Biotech-Drugs of National Health Commission, Jinan, 250062, China
| | - Wenchi Zhang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Yan Xu
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Guangxiang Cao
- Department of Epidemiology, The First Affiliated Hospital of Shandong First Medical University, Jinan, 250062, China. .,Shandong Medicinal Biotechnology Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, 250062, China.
| | - Rongzhen Zhang
- Key Laboratory of Industrial Biotechnology of Ministry of Education and School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
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30
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Hamidian M, Nigro SJ. Emergence, molecular mechanisms and global spread of carbapenem-resistant Acinetobacter baumannii. Microb Genom 2020; 5. [PMID: 31599224 PMCID: PMC6861865 DOI: 10.1099/mgen.0.000306] [Citation(s) in RCA: 160] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen that has emerged as a global threat because of high levels of resistance to many antibiotics, particularly those considered to be last-resort antibiotics, such as carbapenems. Although alterations in the efflux pump and outer membrane proteins can cause carbapenem resistance, the main mechanism is the acquisition of carbapenem-hydrolyzing oxacillinase-encoding genes. Of these, oxa23 is by far the most widespread in most countries, while oxa24 and oxa58 appear to be dominant in specific regions. Historically, much of the global spread of carbapenem resistance has been due to the dissemination of two major clones, known as global clones 1 and 2, although new lineages are now common in some parts of the world. The analysis of all publicly available genome sequences performed here indicates that ST2, ST1, ST79 and ST25 account for over 71 % of all genomes sequenced to date, with ST2 by far the most dominant type and oxa23 the most widespread carbapenem resistance determinant globally, regardless of clonal type. Whilst this highlights the global spread of ST1 and ST2, and the dominance of oxa23 in both clones, it could also be a result of preferential selection of carbapenem-resistant strains, which mainly belong to the two major clones. Furthermore, ~70 % of the sequenced strains have been isolated from five countries, namely the USA, PR China, Australia, Thailand and Pakistan, with only a limited number from other countries. These genomes are a vital resource, but it is currently difficult to draw an accurate global picture of this important superbug, highlighting the need for more comprehensive genome sequence data and genomic analysis.
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Affiliation(s)
- Mohammad Hamidian
- The ithree institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Steven J Nigro
- Communicable Diseases Branch, Health Protection NSW, St Leonards, NSW 2065, Australia
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31
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Hamidian M, Wick RR, Hartstein RM, Judd LM, Holt KE, Hall RM. Insights from the revised complete genome sequences of Acinetobacter baumannii strains AB307-0294 and ACICU belonging to global clones 1 and 2. Microb Genom 2020; 5. [PMID: 31556867 PMCID: PMC6861863 DOI: 10.1099/mgen.0.000298] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Acinetobacter baumannii global clone 1 isolate AB307-0294, recovered in the USA in 1994, and the global clone 2 (GC2) isolate ACICU, isolated in 2005 in Italy, were among the first A. baumannii isolates to be completely sequenced. AB307-0294 is susceptible to most antibiotics and has been used in many genetic studies, and ACICU belongs to a rare GC2 lineage. The complete genome sequences, originally determined using 454 pyrosequencing technology, which is known to generate sequencing errors, were re-determined using Illumina MiSeq and MinION (Oxford Nanopore Technologies) technologies and a hybrid assembly generated using Unicycler. Comparison of the resulting new high-quality genomes to the earlier 454-sequenced versions identified a large number of nucleotide differences affecting protein coding sequence (CDS) features, and allowed the sequences of the long and highly repetitive bap and blp1 genes to be properly resolved for the first time in ACICU. Comparisons of the annotations of the original and revised genomes revealed a large number of differences in the protein CDS features, underlining the impact of sequence errors on protein sequence predictions and core gene determination. On average, 400 predicted CDSs were longer or shorter in the revised genomes and about 200 CDS features were no longer present.
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Affiliation(s)
- Mohammad Hamidian
- The ithree Institute, University of Technology Sydney, Ultimo, NSW, Australia
| | - Ryan R Wick
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Rebecca M Hartstein
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Louise M Judd
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Kathryn E Holt
- London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.,Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Ruth M Hall
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
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32
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Yilmaz Ş, Hasdemir U, Aksu B, Altınkanat Gelmez G, Söyletir G. Alterations in AdeS and AdeR regulatory proteins in 1-(1-naphthylmethyl)-piperazine responsive colistin resistance of Acinetobacter baumannii. J Chemother 2020; 32:286-293. [PMID: 32131715 DOI: 10.1080/1120009x.2020.1735118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Colistin resistant Acinetobacter baumannii strains are of great concern worldwide. However, the role of efflux pumps in colistin resistance needs to be elucidated. We investigated the changes in colistin MICs of 29 colistin resistant A. baumannii isolates in response to resistance-nodulation-division (RND)-type efflux pump inhibitor (EPI) and the alterations in AdeR and AdeS two-component regulatory proteins previously associated with the overproduction of AdeAB. The EPI, 1-(1-naphthylmethyl)-piperazine (NMP), led to significant reductions in colistin MICs. At least one of the following amino acid substitutions was found in AdeS proteins from 18 of the isolates: L172P, A94V, V27I, V32I, G186V, and G164A. Besides, A136V and V120I alterations were identified in AdeR from five isolates. Therefore, EPI-responsive colistin resistance in our isolates is most likely due to the action of an RND-type efflux system. The underlying mechanism of resistance might be the result of certain AdeRS alterations, leading to AdeAB overexpression.
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Affiliation(s)
- Şerife Yilmaz
- Department of Medical Microbiology, Karabuk University Training and Research Hospital, Karabuk, Turkey
| | - Ufuk Hasdemir
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
| | - Burak Aksu
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
| | | | - Güner Söyletir
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
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Kim MH, Jeong H, Sim YM, Lee S, Yong D, Ryu CM, Choi JY. Using comparative genomics to understand molecular features of carbapenem-resistant Acinetobacter baumannii from South Korea causing invasive infections and their clinical implications. PLoS One 2020; 15:e0229416. [PMID: 32084241 PMCID: PMC7034955 DOI: 10.1371/journal.pone.0229416] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 02/05/2020] [Indexed: 12/28/2022] Open
Abstract
Acinetobacter baumannii is a highly potent nosocomial pathogen that is associated with increased in-hospital mortality. Here, we investigated the changes in molecular characteristics of carbapenem-resistant A. baumannii (CRAB) isolated from the blood samples of patients admitted to a tertiary hospital in South Korea from January 2009 to July 2015. Whole genome sequencing using the Illumina MiSeq platform and multi-locus sequence typing (MLST) were performed for 98 CRAB clinical isolates. In silico analyses for the prediction of antimicrobial resistance and virulence factor genes were performed. Plasmid sequences, including complete forms, were reconstructed from the sequence reads. Epidemiologic data were collected from the hospital database. MLST using the Oxford scheme revealed 10 sequence types of CRAB, of which ST191 was the dominant type (n = 59). Although blaOXA-23 was shared by most analysed strains, the compositions of antimicrobial resistance determinants differed among sequence types. ST447 and ST451/ST1809 with a few resistance genes were isolated during the later years of the study period. The number of virulence genes increased, while that of ST191 did not change significantly over the investigation period. Intriguingly MLST types, compositions of antimicrobial resistance genes, and virulence genes had no association with clinical outcomes of CRAB bacteraemia. In conclusion, active changes in or accumulations of antimicrobial resistance determinants and virulence genes in CRAB were not observed during the research period. Molecular characteristics of CRAB had no association with clinical outcomes of CRAB bacteraemia.
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Affiliation(s)
- Min Hyung Kim
- Department of Internal Medicine, Bundang Jesaeng Hospital, Seongam, Gyeonggi, South Korea
- Department of Internal Medicine and AIDS Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Haeyoung Jeong
- Infectious Disease Research Center, KRIBB, Daejeon, South Korea
- R&D Center, Medytox Inc., Suwon, Gyeonggi-do, South Korea
| | - Young Mi Sim
- Infectious Disease Research Center, KRIBB, Daejeon, South Korea
| | - Soohyun Lee
- Infectious Disease Research Center, KRIBB, Daejeon, South Korea
| | - Dongeun Yong
- Department of Laboratory Medicine and Research Institute of antimicrobial resistance, Yonsei University College of Medicine, Seoul, South Korea
| | - Choong-Min Ryu
- Infectious Disease Research Center, KRIBB, Daejeon, South Korea
- * E-mail: (JYC); (CMR)
| | - Jun Yong Choi
- Department of Internal Medicine and AIDS Research Institute, Yonsei University College of Medicine, Seoul, South Korea
- * E-mail: (JYC); (CMR)
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Tomar JS, Hosur RV. Polyamine acetylation and substrate-induced oligomeric states in histone acetyltransferase of multiple drug resistant Acinetobacter baumannii. Biochimie 2019; 168:268-276. [PMID: 31786230 DOI: 10.1016/j.biochi.2019.11.015] [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: 08/08/2019] [Accepted: 11/25/2019] [Indexed: 11/16/2022]
Abstract
Histone acetyltransferase (Hpa2) is an unusual acetyltransferase, with a wide range of substrates; including histones, polyamines and aminoglycosides antibiotic. Hpa2 belongs to GNAT superfamily and GNATs are well known for the formation of homo-oligomers. However, the reason behind their oligomerization remained unexplored. Here, oligomeric states of Hpa2 were explored, to understand the functional significance of oligomerization. Biochemical analysis suggests that Hpa2 exists as dimer in solution and self-assembles into tetramer in the spermine, spermidine and kanamycin bound form. Stability analysis with denaturants concludes that homo-oligomerization of Hpa2 relies on bound substrate and not on experimental conditions. Homo-oligomerization in Hpa2 depicts direct correlation with its polyamine acetylating capacity. This correlation and in silico model structures suggest that oligomerization of Hpa2 is associated with the hastening of acetylation process. Interestingly, polyamine acetylation down regulates biofilms formation in E. coli BL21/Hpa2-transformants cells. Therefore, we propose that Hpa2 manipulates survival strategies of the bacterium via polyamines and antibiotics acetylation.
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Affiliation(s)
- Jyoti Singh Tomar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India.
| | - Ramakrishna Vijayacharya Hosur
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India; UM-DAE Centre for Excellence in Basic Sciences, University Campus Mumbai, India.
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Pollini S, Boncompagni S, Di Maggio T, Di Pilato V, Spanu T, Fiori B, Blasi F, Aliberti S, Sergio F, Rossolini GM, Pallecchi L. In vitro synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii grown in planktonic phase and in biofilms. J Antimicrob Chemother 2019; 73:2388-2395. [PMID: 29846610 PMCID: PMC6105873 DOI: 10.1093/jac/dky185] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/18/2018] [Indexed: 11/14/2022] Open
Abstract
Objectives To investigate the potential synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii strains grown in planktonic phase or as biofilms. Methods Sixteen strains were investigated, including nine colistin-susceptible (MIC range 0.5–1 mg/L) and seven colistin-resistant (MIC range 16–256 mg/L) strains. Synergism of colistin in combination with N-acetylcysteine was investigated by chequerboard assays. The activity of colistin/N-acetylcysteine combinations was further evaluated by time–kill assays with planktonic cultures (three colistin-resistant strains and one colistin-susceptible strain) and by in vitro biofilm models (three colistin-resistant and three colistin-susceptible strains). Results Chequerboard assays revealed a relevant synergism of colistin/N-acetylcysteine combinations with all colistin-resistant strains, whereas no synergism was observed with colistin-susceptible strains. Time–kill assays showed a concentration-dependent potentiation of colistin activity by N-acetylcysteine against colistin-resistant strains, with eradication of the culture by combinations of N-acetylcysteine at 8000 mg/L plus colistin at 2 or 8 mg/L. A static effect during the first 8 h of incubation was demonstrated with the colistin-susceptible strain exposed to 0.25 × MIC colistin plus 8000 mg/L N-acetylcysteine. A remarkable antibiofilm synergistic activity of 8 mg/L colistin plus 8000 mg/L N-acetylcysteine was demonstrated with all colistin-resistant and colistin-susceptible strains. The effects were greater with colistin-resistant strains (marked reduction of viable biofilm cells was observed at sub-MIC colistin concentrations). Conclusions N-acetylcysteine, at concentrations achievable by topical administration, was shown to revert the colistin-resistant phenotype in A. baumannii, and to exert a relevant activity against biofilms of colistin-susceptible and colistin-resistant A. baumannii strains.
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Affiliation(s)
- Simona Pollini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Selene Boncompagni
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Tiziana Di Maggio
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Vincenzo Di Pilato
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Teresa Spanu
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Barbara Fiori
- Institute of Microbiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesco Blasi
- Department of Pathophysiology and Transplantation, University of Milan, Internal Medicine Department, Respiratory Unit and Cystic Fibrosis Adult Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefano Aliberti
- Department of Pathophysiology and Transplantation, University of Milan, Internal Medicine Department, Respiratory Unit and Cystic Fibrosis Adult Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Sergio
- Corporate Respiratory Medical Affairs, Zambon S.p.A., Bresso, Italy
| | - Gian Maria Rossolini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.,Clinical Microbiology and Virology Unit, Careggi University Hospital, Florence, Italy
| | - Lucia Pallecchi
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
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New Shuttle Vectors for Real-Time Gene Expression Analysis in Multidrug-Resistant Acinetobacter Species: In Vitro and In Vivo Responses to Environmental Stressors. Appl Environ Microbiol 2019; 85:AEM.01334-19. [PMID: 31324623 DOI: 10.1128/aem.01334-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 07/06/2019] [Indexed: 11/20/2022] Open
Abstract
The Acinetobacter genus includes species of opportunistic pathogens and harmless saprophytes. The type species, Acinetobacter baumannii, is a nosocomial pathogen renowned for being multidrug resistant (MDR). Despite the clinical relevance of infections caused by MDR A. baumannii and a few other Acinetobacter spp., the regulation of their pathogenicity remains elusive due to the scarcity of adequate genetic tools, including vectors for gene expression analysis. Here, we report the generation and testing of a series of Escherichia coli-Acinetobacter promoter-probe vectors suitable for gene expression analysis in Acinetobacter spp. These vectors, named pLPV1Z, pLPV2Z, and pLPV3Z, carry both gentamicin and zeocin resistance markers and contain lux, lacZ, and green fluorescent protein (GFP) reporter systems downstream of an extended polylinker, respectively. The presence of a toxin-antitoxin gene system and the high copy number allow pLPV plasmids to be stably maintained even without antibiotic selection. The pLPV plasmids can easily be introduced by electroporation into MDR A. baumannii belonging to the major international lineages as well as into species of the Acinetobacter calcoaceticus-A. baumannii complex. The pLPV vectors have successfully been employed to study the regulation of stress-responsive A. baumannii promoters, including the DNA damage-inducible uvrABC promoter, the ethanol-inducible adhP and yahK promoters, and the iron-repressible promoter of the acinetobactin siderophore biosynthesis gene basA A lux-tagged A. baumannii ATCC 19606T strain, carrying the iron-responsive pLPV1Z::PbasA promoter fusion, allowed in vivo and ex vivo monitoring of the bacterial burden in the Galleria mellonella infection model.IMPORTANCE The short-term adaptive response to environmental cues greatly contributes to the ecological success of bacteria, and profound alterations in bacterial gene expression occur in response to physical, chemical, and nutritional stresses. Bacteria belonging to the Acinetobacter genus are ubiquitous inhabitants of soil and water though some species, such as Acinetobacter baumannii, are pathogenic and cause serious concern due to antibiotic resistance. Understanding A. baumannii pathobiology requires adequate genetic tools for gene expression analysis, and to this end we developed user-friendly shuttle vectors to probe the transcriptional responses to different environmental stresses. Vectors were constructed to overcome the problem of antibiotic selection in multidrug-resistant strains and were equipped with suitable reporter systems to facilitate signal detection. By means of these vectors, the transcriptional response of A. baumannii to DNA damage, ethanol exposure, and iron starvation was investigated both in vitro and in vivo, providing insights into A. baumannii adaptation during stress and infection.
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Morris FC, Dexter C, Kostoulias X, Uddin MI, Peleg AY. The Mechanisms of Disease Caused by Acinetobacter baumannii. Front Microbiol 2019; 10:1601. [PMID: 31379771 PMCID: PMC6650576 DOI: 10.3389/fmicb.2019.01601] [Citation(s) in RCA: 158] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 06/26/2019] [Indexed: 01/29/2023] Open
Abstract
Acinetobacter baumannii is a Gram negative opportunistic pathogen that has demonstrated a significant insurgence in the prevalence of infections over recent decades. With only a limited number of “traditional” virulence factors, the mechanisms underlying the success of this pathogen remain of great interest. Major advances have been made in the tools, reagents, and models to study A. baumannii pathogenesis, and this has resulted in a substantial increase in knowledge. This article provides a comprehensive review of the bacterial virulence factors, the host immune responses, and animal models applicable for the study of this important human pathogen. Collating the most recent evidence characterizing bacterial virulence factors, their cellular targets and genetic regulation, we have encompassed numerous aspects important to the success of this pathogen, including membrane proteins and cell surface adaptations promoting immune evasion, mechanisms for nutrient acquisition and community interactions. The role of innate and adaptive immune responses is reviewed and areas of paucity in our understanding are highlighted. Finally, with the vast expansion of available animal models over recent years, we have evaluated those suitable for use in the study of Acinetobacter disease, discussing their advantages and limitations.
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Affiliation(s)
- Faye C Morris
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Carina Dexter
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Xenia Kostoulias
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Muhammad Ikhtear Uddin
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Anton Y Peleg
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, VIC, Australia
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Comparative genome analysis reveals niche-specific genome expansion in Acinetobacter baumannii strains. PLoS One 2019; 14:e0218204. [PMID: 31194814 PMCID: PMC6563999 DOI: 10.1371/journal.pone.0218204] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/28/2019] [Indexed: 12/11/2022] Open
Abstract
The nosocomial pathogen Acinetobacter baumannii acquired clinical significance due to the rapid development of its multi-drug resistant (MDR) phenotype. A. baumannii strains have the ability to colonize several ecological niches including soil, water, and animals, including humans. They also survive under extremely harsh environmental conditions thriving on rare and recalcitrant carbon compounds. However, the molecular basis behind such extreme adaptability of A. baumannii is unknown. We have therefore determined the complete genome sequence of A. baumannii DS002, which was isolated from agricultural soils, and compared it with 78 complete genome sequences of A. baumannii strains having complete information on the source of their isolation. Interestingly, the genome of A. baumannii DS002 showed high similarity to the genome of A. baumannii SDF isolated from the body louse. The environmental and clinical strains, which do not share a monophyletic origin, showed the existence of a strain-specific unique gene pool that supports niche-specific survival. The strains isolated from infected samples contained a genetic repertoire with a unique gene pool coding for iron acquisition machinery, particularly those required for the biosynthesis of acinetobactin. Interestingly, these strains also contained genes required for biofilm formation. However, such gene sets were either partially or completely missing in the environmental isolates, which instead harbored genes required for alternate carbon catabolism and a TonB-dependent transport system involved in the acquisition of iron via siderophores or xenosiderophores.
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Subhadra B, Surendran S, Lim BR, Yim JS, Kim DH, Woo K, Han K, Oh MH, Choi CH. Complete genome sequence and phylogenetic analysis of nosocomial pathogen Acinetobacter nosocomialis strain NCTC 8102. Genes Genomics 2019; 41:1063-1075. [PMID: 31177378 DOI: 10.1007/s13258-019-00834-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 05/20/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Acinetobacter has emerged recently as one of the most challenging nosocomial pathogens because of its increased rate of antimicrobial resistance. The genetic complexity and genome diversity, as well as the lack of adequate knowledge on the pathogenic determinants of Acinetobacter strains often hinder with pathogenesis studies for the development of better therapeutics to tackle this nosocomial pathogen. OBJECTIVES In this study, we comparatively analyzed the whole genome sequence of a virulent Acinetobacternosocomialis strain NCTC 8102. METHODS The genomic DNA of A. nosocomialis NCTC 8102 was isolated and sequenced using PacBio RS II platform. The sequenced genome was functionally annotated and gene prediction was carried out using the program, Glimmer 3. The phylogenetic analysis of the genome was performed using Mega 6 program and the comparative genome analysis was carried out by BLAST (Basic Local Alignment Search Tool). RESULTS The complete genome analysis depicted that the genome consists of a circular chromosome with an average G + C content of 38.7%. The genome comprises 3700 protein-coding genes, 96 RNA genes (18 rRNA, 74 tRNA and 4 ncRNA genes), and 91 pseudogenes. In addition, 6 prophage regions comprising 2 intact, 1 incomplete and 3 questionable ones and 18 genomic islands were identified in the genome, suggesting the possible occurrence of horizontal gene transfer in this strain. Comparative genome analysis of A. nosocomialis NCTC 8102 genome with the already sequenced A. nosocomialis strain SSA3 showed an average nucleotide identity of 99.0%. In addition, the number of prophages and genomic islands were higher in the A. nosocomialis NCTC 8102 genome compared to that of the strain SSA3. 14 of the genomic islands were unique to A. nosocomialis NCTC 8102 compared to strain SSA3 and they harbored genes which are involved in virulence, multidrug resistance, biofilm formation and bacterial pathogenesis. CONCLUSION We sequenced the whole genome of A. nosocomialis strain NCTC 8102 followed by comparatively genome analysis. The study provides valuable information on the genetic features of A. nosocomialis strain and the data from this study would assist in further studies for the development of control measures for this nosocomial pathogen.
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Affiliation(s)
- Bindu Subhadra
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Surya Surendran
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Bo Ra Lim
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Jong-Sung Yim
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Dong Ho Kim
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Kyungho Woo
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea
| | - Kyudong Han
- Department of Nanobiomedical Science, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, 31116, South Korea.,BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan, 31116, South Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, 31116, South Korea.
| | - Chul Hee Choi
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, 266 Munwha-ro, Jung-gu, Daejeon, 35015, South Korea.
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Visca P, Pisa F, Imperi F. The antimetabolite 3-bromopyruvate selectively inhibits Staphylococcus aureus. Int J Antimicrob Agents 2018; 53:449-455. [PMID: 30472291 DOI: 10.1016/j.ijantimicag.2018.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/15/2018] [Accepted: 11/17/2018] [Indexed: 12/12/2022]
Abstract
Increased antibacterial resistance jeopardizes current therapeutic strategies to control infections, soliciting the development of novel antibacterial drugs with new mechanisms of action. This study reports the discovery of potent and selective antistaphylococcal activity of 3-bromopyruvate (3BP), an antimetabolite in preclinical development as an anticancer drug. 3BP showed bactericidal activity against Staphylococcus aureus, with active concentrations comparable with those reported to be effective against cancer cells. In contrast, no relevant activity was observed against other ESKAPE bacteria (Enterococcus faecium, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.). The antistaphylococcal activity of 3BP was confirmed using a panel of human and veterinary strains, including multi-drug-resistant isolates. 3BP showed highest antibacterial activity under conditions that increase its stability (acidic pH) or promote S. aureus fermentative metabolism (anaerobiosis), although 3BP was also able to kill metabolically inactive cells. 3BP showed synergism with gentamicin, and also disrupted preformed S. aureus biofilms at concentrations only slightly higher than those inhibiting planktonic cells. This study unravels novel antibacterial and antibiofilm activities for the anticancer drug 3BP, paving the way for further preclinical studies.
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Affiliation(s)
- Paolo Visca
- Department of Sciences, University 'Roma Tre', Rome, Italy
| | - Federica Pisa
- Department of Sciences, University 'Roma Tre', Rome, Italy; Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
| | - Francesco Imperi
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy.
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Ronish LA, Lillehoj E, Fields JK, Sundberg EJ, Piepenbrink KH. The structure of PilA from Acinetobacter baumannii AB5075 suggests a mechanism for functional specialization in Acinetobacter type IV pili. J Biol Chem 2018; 294:218-230. [PMID: 30413536 DOI: 10.1074/jbc.ra118.005814] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/19/2018] [Indexed: 11/06/2022] Open
Abstract
Type IV pili (T4P) are bacterial appendages composed of protein subunits, called pilins, noncovalently assembled into helical fibers. T4P are essential, in many bacterial species, for processes as diverse as twitching motility, natural competence, biofilm or microcolony formation, and host cell adhesion. The genes encoding type IV pili are found universally in the Gram-negative, aerobic, nonflagellated, and pathogenic coccobacillus Acinetobacter baumannii, but there is considerable variation in PilA, the major protein subunit, both in amino acid sequence and in glycosylation patterns. Here we report the X-ray crystal structure of PilA from AB5075, a recently characterized, highly virulent isolate, at 1.9 Å resolution and compare it to homologues from A. baumannii strains ACICU and BIDMC57, which are C-terminally glycosylated. These structural comparisons revealed that PilAAB5075 exhibits a distinctly electronegative surface chemistry. To understand the functional consequences of this change in surface electrostatics, we complemented a ΔpilA knockout strain with divergent pilA genes from ACICU, BIDMC57, and AB5075. The resulting transgenic strains showed differential twitching motility and biofilm formation while maintaining the ability to adhere to epithelial cells. PilAAB5075 and PilAACICU, although structurally similar, promote different characteristics, favoring twitching motility and biofilm formation, respectively. These results support a model in which differences in pilus electrostatics affect the equilibrium of microcolony formation, which in turn alters the balance between motility and biofilm formation in Acinetobacter.
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Affiliation(s)
- Leslie A Ronish
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Erik Lillehoj
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - James K Fields
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Eric J Sundberg
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201; Departments of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Kurt H Piepenbrink
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Departments of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska 68588.
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Hamidian M, Hall RM. The AbaR antibiotic resistance islands found in Acinetobacter baumannii global clone 1 - Structure, origin and evolution. Drug Resist Updat 2018; 41:26-39. [PMID: 30472242 DOI: 10.1016/j.drup.2018.10.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 10/15/2018] [Accepted: 10/30/2018] [Indexed: 11/28/2022]
Abstract
In multiply resistant Acinetobacter baumannii, complex transposons located in the chromosomal comM gene carry antibiotic and heavy metal resistance determinants. For one type, known collectively as AbaR, the ancestral form, AbaR0, entered a member of global clone 1 (GC1) in the mid 1970s and continued to evolve in situ forming many variants. In AbaR0, antibiotic and mercuric ion resistance genes are located between copies of a cadmium-zinc resistance transposon, Tn6018, and this composite transposon is in a class III transposon, Tn6019, carrying arsenate/arsenite resistance genes and five tni transposition genes. The antibiotic resistance genes in the AbaR0 and derived AbaR3 configurations are aphA1b, blaTEM, catA1, sul1, tetA(A), and cassette-associated aacC1 and aadA1 genes. These genes are in a specific arrangement of fragments from well-known transposons, e.g. Tn1, Tn1721, Tn1696 and Tn2670, that arose in an IncM1 plasmid. All known GC1 lineage 1 isolates carry AbaR0 or AbaR3, which arose around 1990, or a variant derived from one of them. Variants arose via deletions caused by one of three internal IS26s, by recombination between duplicate copies of sul1 or Tn6018, or by gene cassette addition or replacement. A few GC2 isolates also carry an AbaR island with different cassette-associated genes, aacA4 and oxa20.
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Affiliation(s)
- Mohammad Hamidian
- School of Molecular and Microbial Biosciences, The University of Sydney, NSW 2006, Australia; The ithree institute, University of Technology Sydney, Ultimo 2007, NSW, Australia
| | - Ruth M Hall
- School of Molecular and Microbial Biosciences, The University of Sydney, NSW 2006, Australia.
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Emergence of High-Level Colistin Resistance in an Acinetobacter baumannii Clinical Isolate Mediated by Inactivation of the Global Regulator H-NS. Antimicrob Agents Chemother 2018; 62:AAC.02442-17. [PMID: 29712662 DOI: 10.1128/aac.02442-17] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/01/2018] [Indexed: 12/31/2022] Open
Abstract
Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multidrug-resistant strains of the Gram-negative bacterium Acinetobacter baumannii However, colistin-resistant A. baumannii isolates can still be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered a pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment. These strains displayed low and very high levels of colistin resistance (MICs, 8 to 16 μg/ml and 128 μg/ml), respectively. To understand how increased colistin resistance arose, we sequenced the genome of each isolate, which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS family transcriptional regulator. To confirm the role of H-NS in colistin resistance, we generated an hns deletion mutant in 6009-1 and showed that colistin resistance increased upon the deletion of hns We also provided 6009-2 with an intact copy of hns and showed that the strain was no longer resistant to high concentrations of colistin. Transcriptomic analysis of the clinical isolates identified more than 150 genes as being differentially expressed in the colistin-resistant hns mutant 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase but not pmrC, was increased in the hns mutant. This is the first time an H-NS family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
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Abstract
ABSTRACT
The nonfermenting bacteria belonging to
Acinetobacter
spp. and
Pseudomonas
spp. are capable of colonizing both humans and animals and can also be opportunistic pathogens. More specifically, the species
Acinetobacter baumannii
and
Pseudomonas aeruginosa
have been recurrently reported as multidrug-resistant and even pandrug-resistant in clinical isolates. Both species were categorized among the ESKAPE pathogens, ESKAPE standing for
Enterococcus faecium
,
Staphylococcus aureus
,
Klebsiella pneumoniae
,
A. baumannii
,
P. aeruginosa
, and
Enterobacter
species. These six pathogens are the major cause of nosocomial infections in the United States and are a threat all over the world because of their capacity to become increasingly resistant to all available antibiotics.
A. baumannii
and
P. aeruginosa
are both intrinsically resistant to many antibiotics due to complementary mechanisms, the main ones being the low permeability of their outer membrane, the production of the AmpC beta-lactamase, and the production of several efflux systems belonging to the resistance-nodulation-cell division family. In addition, they are both capable of acquiring multiple resistance determinants, such as beta-lactamases or carbapenemases. Even if such enzymes have rarely been identified in bacteria of animal origin, they may sooner or later spread to this reservoir. The goal of this article is to give an overview of the resistance phenotypes described in these pathogens and to provide a comprehensive analysis of all data that have been reported on
Acinetobacter
spp. and
Pseudomonas
spp. from animal hosts.
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Domingues S, Rosário N, Ben Cheikh H, Da Silva GJ. ISAba1 and Tn6168 acquisition by natural transformation leads to third-generation cephalosporins resistance in Acinetobacter baumannii. INFECTION GENETICS AND EVOLUTION 2018; 63:13-16. [PMID: 29758354 DOI: 10.1016/j.meegid.2018.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 11/15/2022]
Abstract
Acinetobacter baumannii has intrinsic beta-lactamase genes, namely ampC and blaOXA-51-like, which are only strongly expressed when the ISAba1 insertion sequence is upstream the 5' end of the genes. A second ampC gene has also been identified in some clinical A. baumannii strains. The increased expression of these genes leads to resistance to beta-lactams, including third-generation cephalosporins and/or carbapenems. The aim of this work was to assess the involvement of natural transformation in the transfer of chromosomal ampC-associated mobile elements, and related changes in the resistance profile of recipient cells. Natural transformation assays with the naturally competent A. baumannii A118 clinical isolate as recipient cell and the multidrug resistant A. baumannii Ab51 clinical isolate as the source of donor DNA produced transformants. All tested transformants showed integration of the ISAba1 close to the ampC gene. In two transformants, the ISAba1 was acquired by transposition and inserted between the usual folE and the ampC genes. The remaining transformants acquired the ISAba1 adjacent to a second ampC gene, as part of Tn6168, likely by homologous recombination. Our study demonstrates that natural transformation can contribute to the widespread of beta-lactams resistance, and acquisition of non-resistant determinants can lead to changes in the susceptibility profile of A. baumannii strains.
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Affiliation(s)
- Sara Domingues
- Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
| | - Natasha Rosário
- Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Hadhemi Ben Cheikh
- Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; Faculty of Science, Bizerta Carthage University, Bizerta, Tunisia; Laboratory of Contagious Disease and Biologically Active Substances LR99-ES27 at Monastir's Pharmacy Faculty, Monastir, Tunisia
| | - Gabriela Jorge Da Silva
- Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
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New Shuttle Vectors for Gene Cloning and Expression in Multidrug-Resistant Acinetobacter Species. Antimicrob Agents Chemother 2018; 62:AAC.02480-17. [PMID: 29339383 DOI: 10.1128/aac.02480-17] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 01/02/2018] [Indexed: 12/28/2022] Open
Abstract
Understanding bacterial pathogenesis requires adequate genetic tools to assess the role of individual virulence determinants by mutagenesis and complementation assays, as well as for homologous and heterologous expression of cloned genes. Our knowledge of Acinetobacter baumannii pathogenesis has so far been limited by the scarcity of genetic tools to manipulate multidrug-resistant (MDR) epidemic strains, which are responsible for most infections. Here, we report on the construction of new multipurpose shuttle plasmids, namely, pVRL1 and pVRL2, which can efficiently replicate in Acinetobacter spp. and in Escherichia coli The pVRL1 plasmid has been constructed by combining (i) the cryptic plasmid pWH1277 from Acinetobacter calcoaceticus, which provides an origin of replication for Acinetobacter spp.; (ii) a ColE1-like origin of replication; (iii) the gentamicin or zeocin resistance cassette for antibiotic selection; and (iv) a multilinker containing several unique restriction sites. Modification of pVRL1 led to the generation of the pVRL2 plasmid, which allows arabinose-inducible gene transcription with an undetectable basal expression level of cloned genes under uninduced conditions and a high dynamic range of responsiveness to the inducer. Both pVRL1 and pVRL2 can easily be selected in MDR A. baumannii, have a narrow host range and a high copy number, are stably maintained in Acinetobacter spp., and appear to be compatible with indigenous plasmids carried by epidemic strains. Plasmid maintenance is guaranteed by the presence of a toxin-antitoxin system, providing more insights into the mechanism of plasmid stability in Acinetobacter spp.
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Elhosseiny NM, Attia AS. Acinetobacter: an emerging pathogen with a versatile secretome. Emerg Microbes Infect 2018; 7:33. [PMID: 29559620 PMCID: PMC5861075 DOI: 10.1038/s41426-018-0030-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/08/2017] [Accepted: 01/09/2018] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii is a notorious pathogen that has emerged as a healthcare nightmare in recent years because it causes serious infections that are associated with high morbidity and mortality rates. Due to its exceptional ability to acquire resistance to almost all available antibiotics, A. baumannii is currently ranked as the first pathogen on the World Health Organization’s priority list for the development of new antibiotics. The versatile range of effectors secreted by A. baumannii represents a large proportion of the virulence arsenal identified in this bacterium to date. Thus, these factors, together with the secretory machinery responsible for their extrusion into the extracellular milieu, are key targets for novel therapeutics that are greatly needed to combat this deadly pathogen. In this review, we provide a comprehensive, up-to-date overview of the organization and regulatory aspects of the Acinetobacter secretion systems, with a special emphasis on their versatile substrates that could be targeted to fight the deadly infections caused by this elusive pathogen.
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Affiliation(s)
- Noha M Elhosseiny
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt.
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Hornsey M, Wareham DW. Effects of In vivo Emergent Tigecycline Resistance on the Pathogenic Potential of Acinetobacter baumannii. Sci Rep 2018. [PMID: 29523824 PMCID: PMC5844891 DOI: 10.1038/s41598-018-22549-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Multidrug-resistant lineages of Acinetobacter baumannii (MDRAB) are important nosocomial pathogens. As tigecycline remains active against most MDRAB we sought to investigate whether tigecycline resistance impacts biological fitness. The effects of treatment-emergent tigecycline resistance were investigated in vitro and in vivo using two pre- (AB210; W6976) and post-therapy (AB211; W7282) clinical pairs, recovered from individual patients, where tigecycline resistance was associated with up-regulated efflux activity. All isolates belonged to the same epidemic UK lineage. Significant differences were observed in end-point survival proportions between AB210 and AB211, but not between W6976 and W7282, using the Galleria mellonella infection model. Isolate AB211 outcompeted AB210 in vivo, in contrast to isolate W7282, which was outcompeted by its pre-therapy counterpart, W6972. Whole-genome sequencing of isolates W6976 and W7282 revealed a mutation in the adeABC regulatory gene, adeS in W7282; resulting in a Ser-8 → Arg substitution. Previous whole-genome comparison of AB210 and AB211 also identified a non-synonymous mutation in adeS, among several other lesions in genes involved in biofilm formation and DNA mismatch repair; consistent with the phenotypic differences described here. In conclusion, the differing effects on the wider phenotype were not predictable from the antibiograms or clonal lineage, despite a common mechanism of tigecycline resistance.
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Affiliation(s)
- Michael Hornsey
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University London, London, UK
| | - David W Wareham
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University London, London, UK. .,Division of Infection, Barts & The London NHS Trust, London, UK.
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49
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Higgins PG, Prior K, Harmsen D, Seifert H. Development and evaluation of a core genome multilocus typing scheme for whole-genome sequence-based typing of Acinetobacter baumannii. PLoS One 2017; 12:e0179228. [PMID: 28594944 PMCID: PMC5464626 DOI: 10.1371/journal.pone.0179228] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/25/2017] [Indexed: 01/05/2023] Open
Abstract
We have employed whole genome sequencing to define and evaluate a core genome multilocus sequence typing (cgMLST) scheme for Acinetobacter baumannii. To define a core genome we downloaded a total of 1,573 putative A. baumannii genomes from NCBI as well as representative isolates belonging to the eight previously described international A. baumannii clonal lineages. The core genome was then employed against a total of fifty-three carbapenem-resistant A. baumannii isolates that were previously typed by PFGE and linked to hospital outbreaks in eight German cities. We defined a core genome of 2,390 genes of which an average 98.4% were called successfully from 1,339 A. baumannii genomes, while Acinetobacter nosocomialis, Acinetobacter pittii, and Acinetobacter calcoaceticus resulted in 71.2%, 33.3%, and 23.2% good targets, respectively. When tested against the previously identified outbreak strains, we found good correlation between PFGE and cgMLST clustering, with 0–8 allelic differences within a pulsotype, and 40–2,166 differences between pulsotypes. The highest number of allelic differences was between the isolates representing the international clones. This typing scheme was highly discriminatory and identified separate A. baumannii outbreaks. Moreover, because a standardised cgMLST nomenclature is used, the system will allow inter-laboratory exchange of data.
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Affiliation(s)
- Paul G. Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, Cologne, Germany
- * E-mail:
| | - Karola Prior
- Department for Periodontology and Restorative Dentistry, University Hospital Muenster, Muenster, Germany
| | - Dag Harmsen
- Department for Periodontology and Restorative Dentistry, University Hospital Muenster, Muenster, Germany
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, Cologne, Germany
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Kikuchi-Ueda T, Kamoshida G, Ubagai T, Nakano R, Nakano A, Akuta T, Hikosaka K, Tansho-Nagakawa S, Kikuchi H, Ono Y. The TNF-α of mast cells induces pro-inflammatory responses during infection with Acinetobacter baumannii. Immunobiology 2017; 222:1025-1034. [PMID: 28595750 DOI: 10.1016/j.imbio.2017.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/18/2017] [Accepted: 05/23/2017] [Indexed: 01/12/2023]
Abstract
Mast cells serve important roles as sentinels against bacterial infection by secreting mediators stored in granules. Much of their effectiveness depends upon recruiting and/or modulating other immune cells. The location of mast cells implies that they recognize pathogens invading tissues or mucosal tissues. Acinetobacter baumannii is a gram-negative bacterium that is considered an emerging nosocomial pathogen and causes a wide range of infections associated with high morbidity and mortality. To date, the interaction of A. baumannii with mast cells remains unclear. In this study, we demonstrated an interaction between human LAD2 mast cells and A. baumannii in vitro. When LAD2 cells were co-cultured with live A. baumannii or Pseudomonas aeruginosa PAO1 in vitro for 4h, TNF-α and IL-8 were produced in the culture supernatant. These inflammatory cytokines were not detected in the supernatant after the cells were treated with live bacteria without serum. Gene expression analysis showed that TNF-α and IL-8 mRNA expression increased in A. baumannii- and P. aeruginosa-infected LAD2 cells. Scanning electron microscopy showed that A. baumannii was tightly attached to the surface of LAD2 cells and suggested that A. baumannii may bind to FcγRII (CD32) on LAD2 cells. TNF-α in the culture supernatant from A. baumannii-infected LAD2 cells, showed that PMN activation and migration increased in Boyden chamber assays. These results suggest that mast cells recognize and initiate immune responses toward A. baumannii by releasing the preformed mediator TNF-α to activate effector neutrophils.
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Affiliation(s)
- Takane Kikuchi-Ueda
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Go Kamoshida
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Tsuneyuki Ubagai
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Ryuichi Nakano
- Department of Microbiology and Infectious Diseases, Nara Medical University, 840 Shijo-cho, Kashihara-shi, Nara 634-8521, Japan.
| | - Akiyo Nakano
- Department of Microbiology and Infectious Diseases, Nara Medical University, 840 Shijo-cho, Kashihara-shi, Nara 634-8521, Japan.
| | - Teruo Akuta
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Kenji Hikosaka
- Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
| | - Shigeru Tansho-Nagakawa
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Hirotoshi Kikuchi
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Yasuo Ono
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
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