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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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Singh S, Singh S, Trivedi M, Dwivedi M. An insight into MDR Acinetobacter baumannii infection and its pathogenesis: Potential therapeutic targets and challenges. Microb Pathog 2024; 192:106674. [PMID: 38714263 DOI: 10.1016/j.micpath.2024.106674] [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: 10/19/2023] [Revised: 04/22/2024] [Accepted: 05/01/2024] [Indexed: 05/09/2024]
Abstract
Acinetobacter baumannii is observed as a common species of Gram-negative bacteria that exist in soil and water. Despite being accepted as a typical component of human skin flora, it has become an important opportunistic pathogen, especially in healthcare settings. The pathogenicity of A. baumannii is attributed to its virulence factors, which include adhesins, pili, lipopolysaccharides, outer membrane proteins, iron uptake systems, autotransporter, secretion systems, phospholipases etc. These elements provide the bacterium the ability to cling to and penetrate host cells, get past the host immune system, and destroy tissue. Its infection is a major contributor to human pathophysiological conditions including pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. It is challenging to treat infections brought on by this pathogen since this bacterium has evolved to withstand numerous drugs and further emergence of drug-resistant A. baumannii results in higher rates of morbidity and mortality. The long-term survival of this bacterium on surfaces of medical supplies and hospital furniture facilitates its frequent spread in humans from one habitat to another. There is a need for urgent investigations to find effective drug targets for A. baumannii as well as designing novel drugs to reduce the survival and spread of infection. In the current review, we represent the specific features, pathogenesis, and molecular intricacies of crucial drug targets of A. baumannii. This would also assist in proposing strategies and alternative therapies for the prevention and treatment of A. baumannii infections and their spread.
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Affiliation(s)
- Sukriti Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Sushmita Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Mala Trivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India; Research Cell, Amity University Uttar Pradesh, Lucknow, 226028, India.
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3
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Pfefferle K, Averhoff B. Wax Ester and Triacylglycerol Production in Acinetobacter baumannii: Role in Osmostress Protection, Reactive Oxygen Species, and Antibiotic Sensitivity. ACS Infect Dis 2023; 9:2093-2104. [PMID: 37883671 DOI: 10.1021/acsinfecdis.3c00214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Wax esters (WEs) are neutral lipids that are produced by many different bacteria as potential carbon and energy storage compounds. Comparatively little is known about the role of WE in pathogenic bacteria. The opportunistic pathogen Acinetobacter baumannii is a major cause of hospital-acquired infections worldwide. Salt and desiccation resistance foster A. baumannii infections such as urinary tract infections and allow for reinfection when bacteria are taken up from dry surfaces in the hospital environment. Here we report on WE and triacylglycerol (TAG) production in A. baumannii as a response to nitrogen limitation and high salt stress. Fatty acids and fatty alcohols with chain lengths of C16 and C18 were identified as the most prominent WE constituents. We identified the terminal key enzyme of WE biosynthesis, the bifunctional wax ester synthase/acylCoA:diacylglycerol acyltransferase (WS/DGAT) encoded by the wax/dgat gene, and demonstrated that transcription of wax/dgat and production of WS/DGAT are independent of the nitrogen concentration. A Δwax/dgat mutant was impaired in growth in the presence of high salt concentration and was more sensitive to imipenem and reactive oxygen species.
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Affiliation(s)
- Katharina Pfefferle
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, 60438 Frankfurt, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, 60438 Frankfurt, Germany
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Alberti L, König P, Zeidler S, Poehlein A, Daniel R, Averhoff B, Müller V. Identification and characterization of a novel pathway for aldopentose degradation in Acinetobacter baumannii. Environ Microbiol 2023; 25:2416-2430. [PMID: 37522309 DOI: 10.1111/1462-2920.16471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 07/14/2023] [Indexed: 08/01/2023]
Abstract
The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L-arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α-ketoglutarate. Molecular, genetic, and biochemical experiments revealed one branch to be specific for L-arabonate oxidation, and the other for D-xylonate and D-ribonate. Both clusters also encode an uptake system and a regulator that acts as activator (L-arabonate) or repressor (D-xylonate and D-ribonate). Genes encoding the initial oxidation of pentose to pentonate were not part of the clusters, but our data are consistent with the hypothesis of a promiscous, pyrroloquinoline quinone (PQQ)-dependent, periplasmic pentose dehydrogenase, followed by the uptake of the pentonates and their degradation by specific pathways. However, there is a cross-talk between the two different pathways since the isoenzymes can replace each other. Growth on pentoses was found only in pathogenic Acinetobacter species but not in non-pathogenic such as Acinetobacter baylyi. However, mutants impaired in growth on pentoses were not affected in traits important for infection, but growth on L-arabinose was beneficial for long-term survival and desiccation resistance in A. baumannii ATCC 19606.
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Affiliation(s)
- Lydia Alberti
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Patricia König
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Sabine Zeidler
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
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König P, Wilhelm A, Schaudinn C, Poehlein A, Daniel R, Widera M, Averhoff B, Müller V. The VBNC state: a fundamental survival strategy of Acinetobacter baumannii. mBio 2023; 14:e0213923. [PMID: 37768061 PMCID: PMC10653857 DOI: 10.1128/mbio.02139-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 08/14/2023] [Indexed: 09/29/2023] Open
Abstract
IMPORTANCE Currently, the viable but non-culturable (VBNC) state is an underappreciated niche for pathogenic bacteria which provides a continuous source for recurrent infections and transmission. We propose the VBNC state to be a global persistence mechanism used by various A. baumannii strains to cope with many stresses it is confronted with in the clinical environment and in the host. This requires a novel strategy to detect viable cells of this pathogen that is not only based on plating assays.
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Affiliation(s)
- Patricia König
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University, Frankfurt am Main, Germany
| | - Alexander Wilhelm
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany
| | - Christoph Schaudinn
- Advanced Light and Electron Microscopy ZBS4, Robert-Koch-Institute, Berlin, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Marek Widera
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University, Frankfurt am Main, Germany
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Iruegas R, Pfefferle K, Göttig S, Averhoff B, Ebersberger I. Feature architecture aware phylogenetic profiling indicates a functional diversification of type IVa pili in the nosocomial pathogen Acinetobacter baumannii. PLoS Genet 2023; 19:e1010646. [PMID: 37498819 PMCID: PMC10374093 DOI: 10.1371/journal.pgen.1010646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/06/2023] [Indexed: 07/29/2023] Open
Abstract
The Gram-negative bacterial pathogen Acinetobacter baumannii is a major cause of hospital-acquired opportunistic infections. The increasing spread of pan-drug resistant strains makes A. baumannii top-ranking among the ESKAPE pathogens for which novel routes of treatment are urgently needed. Comparative genomics approaches have successfully identified genetic changes coinciding with the emergence of pathogenicity in Acinetobacter. Genes that are prevalent both in pathogenic and a-pathogenic Acinetobacter species were not considered ignoring that virulence factors may emerge by the modification of evolutionarily old and widespread proteins. Here, we increased the resolution of comparative genomics analyses to also include lineage-specific changes in protein feature architectures. Using type IVa pili (T4aP) as an example, we show that three pilus components, among them the pilus tip adhesin ComC, vary in their Pfam domain annotation within the genus Acinetobacter. In most pathogenic Acinetobacter isolates, ComC displays a von Willebrand Factor type A domain harboring a finger-like protrusion, and we provide experimental evidence that this finger conveys virulence-related functions in A. baumannii. All three genes are part of an evolutionary cassette, which has been replaced at least twice during A. baumannii diversification. The resulting strain-specific differences in T4aP layout suggests differences in the way how individual strains interact with their host. Our study underpins the hypothesis that A. baumannii uses T4aP for host infection as it was shown previously for other pathogens. It also indicates that many more functional complexes may exist whose precise functions have been adjusted by modifying individual components on the domain level.
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Affiliation(s)
- Ruben Iruegas
- Applied Bioinformatics Group, Inst of Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Katharina Pfefferle
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stephan Göttig
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Beate Averhoff
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Ingo Ebersberger
- Applied Bioinformatics Group, Inst of Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt am Main, Germany
- Senckenberg Biodiversity and Climate Research Centre (S-BIK-F), Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics (TBG), Frankfurt am Main, Germany
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Hubloher JJ, Van der Sande L, Schaudinn C, Müller V, Averhoff B. The Tol-Pal system of Acinetobacter baumannii is important for cell morphology, antibiotic resistance and virulence. Int Microbiol 2023:10.1007/s10123-022-00319-9. [PMID: 36648597 PMCID: PMC10397113 DOI: 10.1007/s10123-022-00319-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/27/2022] [Accepted: 12/30/2022] [Indexed: 01/18/2023]
Abstract
Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions. This Gram-negative bacterium is one of the most successful human pathogens worldwide and responsible for hospital-acquired infections. This is due to its outstanding potential to adapt to very different environments, to persist in the human host and most important, its ability to develop multidrug resistance. Our combined approach of genomic and phenotypic analyses led to the identification of the envelope spanning Tol-Pal system in A. baumannii. We found that the deletion of the tolQ, tolR, tolA, tolB, and pal genes affects cell morphology and increases antibiotic sensitivity, such as the ∆tol-pal mutant exhibits a significantly increased gentamicin and bacitracin sensitivity. Furthermore, Galleria mellonella caterpillar killing assays revealed that the ∆tol-pal mutant exhibits a decreased killing phenotype. Taken together, our findings suggest that the Tol-Pal system is important for cell morphology, antibiotic resistance, and virulence of A. baumannii.
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Affiliation(s)
- Josephine Joy Hubloher
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt Am Main, Max-Von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Lisa Van der Sande
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt Am Main, Max-Von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Christoph Schaudinn
- Advanced Light and Electron Microscopy ZBS4, Robert-Koch-Institut, Berlin, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt Am Main, Max-Von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt Am Main, Max-Von-Laue-Str. 9, 60438, Frankfurt, Germany.
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