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Jeong GJ, Khan F, Tabassum N, Kim YM. Motility of Acinetobacter baumannii: regulatory systems and controlling strategies. Appl Microbiol Biotechnol 2024; 108:3. [PMID: 38159120 DOI: 10.1007/s00253-023-12975-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/08/2023] [Accepted: 11/13/2023] [Indexed: 01/03/2024]
Abstract
Acinetobacter baumannii is a Gram-negative opportunistic zoonotic pathogenic bacterium that causes nosocomial infections ranging from minor to life-threatening. The clinical importance of this zoonotic pathogen is rapidly increasing due to the development of multiple resistance mechanisms and the synthesis of numerous virulence factors. Although no flagellum-mediated motility exists, it may move through twitching or surface-associated motility. Twitching motility is a coordinated multicellular movement caused by the extension, attachment, and retraction of type IV pili, which are involved in surface adherence and biofilm formation. Surface-associated motility is a kind of movement that does not need appendages and is most likely driven by the release of extra polymeric molecules. This kind of motility is linked to the production of 1,3-diaminopropane, lipooligosaccharide formation, natural competence, and efflux pump proteins. Since A. baumannii's virulence qualities are directly tied to motility, it is possible that its motility may be used as a specialized preventative or therapeutic measure. The current review detailed the signaling mechanism and involvement of various proteins in controlling A. baumannii motility. As a result, we have thoroughly addressed the role of natural and synthetic compounds that impede A. baumannii motility, as well as the underlying action mechanisms. Understanding the regulatory mechanisms behind A. baumannii's motility features will aid in the development of therapeutic drugs to control its infection. KEY POINTS: • Acinetobacter baumannii exhibits multiple resistance mechanisms. • A. baumannii can move owing to twitching and surface-associated motility. • Natural and synthetic compounds can attenuate A. baumannii motility.
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Affiliation(s)
- Geum-Jae Jeong
- Department of Food Science and Technology, Pukyong National University, Busan, 48513, Republic of Korea
| | - Fazlurrahman Khan
- Institute of Fisheries Sciences, Pukyong National University, Busan, 48513, Republic of Korea.
- Marine Integrated Biomedical Technology Center, The National Key Research Institutes in Universities, Pukyong National University, Busan, 48513, Republic of Korea.
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, Republic of Korea.
| | - Nazia Tabassum
- Marine Integrated Biomedical Technology Center, The National Key Research Institutes in Universities, Pukyong National University, Busan, 48513, Republic of Korea
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, Republic of Korea
| | - Young-Mog Kim
- Department of Food Science and Technology, Pukyong National University, Busan, 48513, Republic of Korea.
- Marine Integrated Biomedical Technology Center, The National Key Research Institutes in Universities, Pukyong National University, Busan, 48513, Republic of Korea.
- Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan, 48513, Republic of Korea.
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2
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Ren J, Wang M, Zhou W, Liu Z. Efflux pumps as potential targets for biofilm inhibition. Front Microbiol 2024; 15:1315238. [PMID: 38596384 PMCID: PMC11002903 DOI: 10.3389/fmicb.2024.1315238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/26/2024] [Indexed: 04/11/2024] Open
Abstract
Biofilms account for a great deal of infectious diseases and contribute significantly to antimicrobial resistance. Efflux pumps confer antimicrobial resistance to microorganisms and involve multiple processes of biofilm formation. Efflux pump inhibitors (EPIs) are attracting considerable attention as a biofilm inhibition strategy. The regulatory functions of efflux pumps in biofilm formation such as mediating adherence, quorum sensing (QS) systems, and the expression of biofilm-associated genes have been increasingly identified. The versatile properties confer efflux pumps both positive and negative effects on biofilm formation. Furthermore, the expression and function of efflux pumps in biofilm formation are species-specific. Therefore, this review aims to detail the double-edged sword role of efflux pumps in biofilm formation to provide potential inhibition targets and give an overview of the effects of EPIs on biofilm formation.
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Affiliation(s)
| | | | - Wenjuan Zhou
- Department of Implantology, Yantai Stomatological Hospital Affiliated to Binzhou Medical University, Yantai, China
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3
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Di Pilato V, Willison E, Marchese A. The microbiology and pathogenesis of nonfermenting Gram-negative infections. Curr Opin Infect Dis 2023; 36:537-544. [PMID: 37732777 PMCID: PMC10624403 DOI: 10.1097/qco.0000000000000969] [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: 09/22/2023]
Abstract
PURPOSE OF REVIEW This review provides an overview of most recent evidence about pathogenesis traits and virulence factors contributing to successful colonization or infection by P. aeruginosa , A. baumannii , S. maltophilia and B. cepacia complex, among the most clinically relevant nonfermenting Gram-negative bacteria (NFGNB). RECENT FINDINGS The growing clinical importance of NFGNB as important opportunistic pathogens causing difficult-to-treat infections in a fragile patients' population in stressed by numerous studies. Identification of novel virulence factors and deciphering of their mechanisms of action have greatly furthered our understanding of NFGNB pathogenesis, revealing that each pathogen-specific armamentarium of virulence factors (adhesins, motility, capsule, biofilm, lipopolysaccharide, exotoxins, exoenzymes, secretion systems, siderophores) can be likely responsible for the difference in the pathophysiology even in the context of a similar infection site. Emerging evidence of the immunomodulatory effect of some virulence factors is also acknowledged. SUMMARY NFGNB continue to be a serious global problem as cause of life-threatening opportunistic infections, owing to a highly heterogeneous content of virulence factors and their extensive number of intrinsic resistance mechanisms. Further efforts in development of novel effective antimicrobials and of alternative strategies targeting key virulence factors are warranted.
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Affiliation(s)
- Vincenzo Di Pilato
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa
| | - Edward Willison
- Microbiology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Anna Marchese
- Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa
- Microbiology Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
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Armalytė J, Čepauskas A, Šakalytė G, Martinkus J, Skerniškytė J, Martens C, Sužiedėlienė E, Garcia-Pino A, Jurėnas D. A polyamine acetyltransferase regulates the motility and biofilm formation of Acinetobacter baumannii. Nat Commun 2023; 14:3531. [PMID: 37316480 DOI: 10.1038/s41467-023-39316-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 06/07/2023] [Indexed: 06/16/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen highly resistant to environmental changes and antimicrobial treatments. Regulation of cellular motility and biofilm formation is important for its virulence, although it is poorly described at the molecular level. It has been previously reported that Acinetobacter genus specifically produces a small positively charged metabolite, polyamine 1,3-diaminopropane, that has been associated with cell motility and virulence. Here we show that A. baumannii encodes novel acetyltransferase, Dpa, that acetylates 1,3-diaminopropane, directly affecting the bacterium motility. Expression of dpa increases in bacteria that form pellicle and adhere to eukaryotic cells as compared to planktonic bacterial cells, suggesting that cell motility is linked to the pool of non-modified 1,3-diaminopropane. Indeed, deletion of dpa hinders biofilm formation and increases twitching motion confirming the impact of balancing the levels of 1,3-diaminopropane on cell motility. The crystal structure of Dpa reveals topological and functional differences from other bacterial polyamine acetyltransferases, adopting a β-swapped quaternary arrangement similar to that of eukaryotic polyamine acetyltransferases with a central size exclusion channel that sieves through the cellular polyamine pool. The structure of catalytically impaired DpaY128F in complex with the reaction product shows that binding and orientation of the polyamine substrates are conserved between different polyamine-acetyltransferases.
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Affiliation(s)
- Julija Armalytė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Albinas Čepauskas
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles (ULB), Building BC, Room 1C4 203, Boulevard du Triomphe, 1050, Brussels, Belgium
| | - Gabija Šakalytė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Julius Martinkus
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Jūratė Skerniškytė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Chloé Martens
- Centre for Structural Biology and Bioinformatics, Université Libre de Bruxelles (ULB), Bruxelles, Belgium. Building BC, Boulevard du Triomphe, 1050, Brussels, Belgium
| | - Edita Sužiedėlienė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania
| | - Abel Garcia-Pino
- Cellular and Molecular Microbiology, Faculté des Sciences, Université Libre de Bruxelles (ULB), Building BC, Room 1C4 203, Boulevard du Triomphe, 1050, Brussels, Belgium.
| | - Dukas Jurėnas
- Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania.
- Laboratoire de Génétique et Physiologie Bactérienne, Faculté des Sciences, Université Libre de Bruxelles (ULB), 12 Rue des Profs. Jeener et Brachet, B-6041, Gosselies, Belgium.
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Shadan A, Pathak A, Ma Y, Pathania R, Singh RP. Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infection. Front Cell Infect Microbiol 2023; 13:1053968. [PMID: 36968113 PMCID: PMC10038080 DOI: 10.3389/fcimb.2023.1053968] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infectionAcinetobacter baumannii is a gram-negative multidrug-resistant nosocomial pathogen and a major cause of hospital acquired infetions. Carbapenem resistant A. baumannii has been categorised as a Priority1 critial pathogen by the World Health Organisation. A. baumannii is responsible for infections in hospital settings, clinical sectors, ventilator-associated pneumonia, and bloodstream infections with a mortality rates up to 35%. With the development of advanced genome sequencing, molecular mechanisms of manipulating bacterial genomes, and animal infection studies, it has become more convenient to identify the factors that play a major role in A. baumannii infection and its persistence. In the present review, we have explored the mechanism of infection, virulence factors, and various other factors associated with the pathogenesis of this organism. Additionally, the role of the innate and adaptive immune response, and the current progress in the development of innovative strategies to combat this multidrug-resistant pathogen is also discussed.
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Affiliation(s)
- Afreen Shadan
- Department of Microbiology, Dr. Shyama Prasad Mukherjee University, Ranchi, Jharkhand, India
| | - Avik Pathak
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
| | - Ying Ma
- College of Resources and Environment, Southwest University, Chongqing, China
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Ranjana Pathania
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Ranchi, Jharkhand, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
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An Unprecedented Tolerance to Deletion of the Periplasmic Chaperones SurA, Skp, and DegP in the Nosocomial Pathogen Acinetobacter baumannii. J Bacteriol 2022; 204:e0005422. [PMID: 36106853 PMCID: PMC9578438 DOI: 10.1128/jb.00054-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria efficiently protects from harmful environmental stresses such as antibiotics, disinfectants, or dryness. The main constituents of the OM are integral OM β-barrel proteins (OMPs). In Gram-negative bacteria such as Escherichia coli, Yersinia enterocolitica, and Pseudomonas aeruginosa, the insertion of OMPs depends on a sophisticated biogenesis pathway. This comprises the SecYEG translocon, which enables inner membrane (IM) passage; the chaperones SurA, Skp, and DegP, which facilitate the passage of β-barrel OMPs through the periplasm; and the β-barrel assembly machinery (BAM), which facilitates insertion into the OM. In E. coli, Y. enterocolitica, and P. aeruginosa, the deletion of SurA is particularly detrimental and leads to a loss of OM integrity, sensitization to antibiotic treatment, and reduced virulence. In search of targets that could be exploited to develop compounds that interfere with OM integrity in Acinetobacter baumannii, we employed the multidrug-resistant strain AB5075 to generate single gene knockout strains lacking individual periplasmic chaperones. In contrast to E. coli, Y. enterocolitica, and P. aeruginosa, AB5075 tolerates the lack of SurA, Skp, or DegP with only weak mutant phenotypes. While the double knockout strains ΔsurAΔskp and ΔsurAΔdegP are conditionally lethal in E. coli, all double deletions were well tolerated by AB5075. Strikingly, even a triple-knockout strain of AB5075, lacking surA, skp, and degP, was viable. IMPORTANCEAcinetobacter baumannii is a major threat to human health due to its ability to persist in the hospital environment, resistance to antibiotic treatment, and ability to deploy multiple and redundant virulence factors. In a rising number of cases, infections with multidrug-resistant A. baumannii end up fatally, because all antibiotic treatment options fail. Thus, novel targets have to be identified and alternative therapeutics have to be developed. The knockout of periplasmic chaperones has previously proven to significantly reduce virulence and even break antibiotic resistance in other Gram-negative pathogens. Our study in A. baumannii demonstrates how variable the importance of the periplasmic chaperones SurA, Skp, and DegP can be and suggests the existence of mechanisms allowing A. baumannii to cope with the lack of the three periplasmic chaperones.
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Perchat N, Dubois C, Mor-Gautier R, Duquesne S, Lechaplais C, Roche D, Fouteau S, Darii E, Perret A. Characterization of a novel β-alanine biosynthetic pathway consisting of promiscuous metabolic enzymes. J Biol Chem 2022; 298:102067. [PMID: 35623386 PMCID: PMC9213253 DOI: 10.1016/j.jbc.2022.102067] [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] [Received: 12/16/2021] [Revised: 05/19/2022] [Accepted: 05/22/2022] [Indexed: 10/28/2022] Open
Abstract
Bacteria adapt to utilize the nutrients available in their environment through a sophisticated metabolic system composed of highly specialized enzymes. Although these enzymes can metabolize molecules other than those for which they evolved, their efficiency toward promiscuous substrates is considered too low to be of physiological relevance. Herein, we investigated the possibility that these promiscuous enzymes are actually efficient enough at metabolizing secondary substrates to modify the phenotype of the cell. For example, in the bacterium Acinetobacter baylyi ADP1 (ADP1), panD (coding for l-aspartate decarboxylase) encodes the only protein known to catalyze the synthesis of β-alanine, an obligate intermediate in CoA synthesis. However, we show that the ADP1 ΔpanD mutant could also form this molecule through an unknown metabolic pathway arising from promiscuous enzymes and grow as efficiently as the wildtype strain. Using metabolomic analyses, we identified 1,3-diaminopropane and 3-aminopropanal as intermediates in this novel pathway. We also conducted activity screening and enzyme kinetics to elucidate candidate enzymes involved in this pathway, including 2,4-diaminobutyrate aminotransferase (Dat) and 2,4-diaminobutyrate decarboxylase (Ddc) and validated this pathway in vivo by analyzing the phenotype of mutant bacterial strains. Finally, we experimentally demonstrate that this novel metabolic route is not restricted to ADP1. We propose that the occurrence of conserved genes in hundreds of genomes across many phyla suggests that this previously undescribed pathway is widespread in prokaryotes.
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Affiliation(s)
- Nadia Perchat
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Christelle Dubois
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Rémi Mor-Gautier
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Sophie Duquesne
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Christophe Lechaplais
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - David Roche
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Stéphanie Fouteau
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Ekaterina Darii
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France
| | - Alain Perret
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, Evry, France.
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Tao Y, Duma L, Rossez Y. Galleria mellonella as a Good Model to Study Acinetobacter baumannii Pathogenesis. Pathogens 2021; 10:1483. [PMID: 34832638 PMCID: PMC8623143 DOI: 10.3390/pathogens10111483] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 12/29/2022] Open
Abstract
The invertebrate model, Galleria mellonella, has been widely used to study host-pathogen interactions due to its cheapness, ease of handling, and similar mammalian innate immune system. G. mellonella larvae have been proven to be useful and a reliable model for analyzing pathogenesis mechanisms of multidrug resistant Acinetobacter baumannii, an opportunistic pathogen difficult to kill. This review describes the detailed experimental design of G. mellonella/A. baumannii models, and provides a comprehensive comparison of various virulence factors and therapy strategies using the G. mellonella host. These investigations highlight the importance of this host-pathogen model for in vivo pathogen virulence studies. On the long term, further development of the G. mellonella/A. baumannii model will offer promising insights for clinical treatments of A. baumannii infection.
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Affiliation(s)
- Ye Tao
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de Recherche Royallieu–CS 60 319 , 60203 Compiègne, France; (Y.T.); (L.D.)
| | - Luminita Duma
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de Recherche Royallieu–CS 60 319 , 60203 Compiègne, France; (Y.T.); (L.D.)
- Université de Reims Champagne-Ardenne, CNRS, ICMR UMR 7312, 51097 Reims, France
| | - Yannick Rossez
- Université Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
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Short FL, Liu Q, Shah B, Clift HE, Naidu V, Li L, Prity FT, Mabbutt BC, Hassan KA, Paulsen IT. The Acinetobacter baumannii disinfectant resistance protein, AmvA, is a spermidine and spermine efflux pump. Commun Biol 2021; 4:1114. [PMID: 34552198 PMCID: PMC8458285 DOI: 10.1038/s42003-021-02629-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 09/01/2021] [Indexed: 02/08/2023] Open
Abstract
Antimicrobial resistance genes, including multidrug efflux pumps, evolved long before the ubiquitous use of antimicrobials in medicine and infection control. Multidrug efflux pumps often transport metabolites, signals and host-derived molecules in addition to antibiotics or biocides. Understanding their ancestral physiological roles could inform the development of strategies to subvert their activity. In this study, we investigated the response of Acinetobacter baumannii to polyamines, a widespread, abundant class of amino acid-derived metabolites, which led us to identify long-chain polyamines as natural substrates of the disinfectant efflux pump AmvA. Loss of amvA dramatically reduced tolerance to long-chain polyamines, and these molecules induce expression of amvA through binding to its cognate regulator AmvR. A second clinically-important efflux pump, AdeABC, also contributed to polyamine tolerance. Our results suggest that the disinfectant resistance capability that allows A. baumannii to survive in hospitals may have evolutionary origins in the transport of polyamine metabolites.
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Affiliation(s)
- Francesca L. Short
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia ,grid.1002.30000 0004 1936 7857Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC Australia
| | - Qi Liu
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Bhumika Shah
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Heather E. Clift
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia ,grid.280427.b0000 0004 0434 015XPresent Address: Versiti Blood Research Institute, Milwaukee, WI USA
| | - Varsha Naidu
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Liping Li
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Farzana T. Prity
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Bridget C. Mabbutt
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Karl A. Hassan
- grid.266842.c0000 0000 8831 109XSchool of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW Australia
| | - Ian T. Paulsen
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
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Corral J, Pérez-Varela M, Sánchez-Osuna M, Cortés P, Barbé J, Aranda J. Importance of twitching and surface-associated motility in the virulence of Acinetobacter baumannii. Virulence 2021; 12:2201-2213. [PMID: 34515614 PMCID: PMC8451467 DOI: 10.1080/21505594.2021.1950268] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Acinetobacter baumannii is a pathogen of increasing clinical importance worldwide, especially given its ability to readily acquire resistance determinants. Motile strains of this bacterium can move by either or both of two types of motility: (i) twitching, driven by type IV pili, and (ii) surface-associated motility, an appendage-independent form of movement. A. baumannii strain MAR002 possesses both twitching and surface-associated motility. In this study, we isolated spontaneous rifampin-resistant mutants of strain MAR002 in which point mutations in the rpoB gene were identified that resulted in an altered motility pattern. Transcriptomic analysis of mutants lacking twitching, surface-associated motility, or both led to the identification of deregulated genes within each motility phenotype, based on their level of expression and their biological function. Investigations of the corresponding knockout mutants revealed several genes involved in the motility of A. baumannii strain MAR002, including two involved in twitching (encoding a minor pilin subunit and an RND [resistance nodulation division] component), one in surface-associated motility (encoding an amino acid permease), and eight in both (encoding RND and ABC components, the energy transducer TonB, the porin OprD, the T6SS component TagF, an IclR transcriptional regulator, a PQQ-dependent sugar dehydrogenase, and a putative pectate lyase). Virulence assays showed the reduced pathogenicity of mutants with impairments in both types of motility or in surface-associated motility alone. By contrast, the virulence of twitching-affected mutants was not affected. These results shed light on the key role of surface-associated motility and the limited role of twitching in the pathogenicity of A. baumannii.
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Affiliation(s)
- Jordi Corral
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
| | - María Pérez-Varela
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
| | - Miquel Sánchez-Osuna
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
| | - Pilar Cortés
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
| | - Jordi Barbé
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
| | - Jesús Aranda
- Departament De Genètica I Microbiologia, Facultat De Biociènces, Universitat Autònoma De Barcelona, Barcelona, Spain
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11
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Kim K, Islam M, Jung HW, Lim D, Kim K, Lee SG, Park C, Lee JC, Shin M. ppGpp signaling plays a critical role in virulence of Acinetobacter baumannii. Virulence 2021; 12:2122-2132. [PMID: 34375563 PMCID: PMC8366539 DOI: 10.1080/21505594.2021.1961660] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acinetobacter baumannii, a major nosocomial pathogen, survives in diverse hospital environments, and its multidrug resistance is a major concern. The ppGpp-dependent stringent response mediates the reprogramming of genes with diverse functions in several bacteria. We investigated whether ppGpp is involved in A. baumannii’s pathogenesis by examining biofilm formation, surface motility, adhesion, invasion, and mouse infection studies. Transcriptome analysis of early stationary phase cultures revealed 498 differentially-expressed genes (≥ 2-fold change) in a ppGpp-deficient A. baumannii strain; 220 and 278 genes were up and downregulated, respectively. Csu operon expression, important in pilus biosynthesis during early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings suggest that ppGpp signaling influences A. baumannii biofilm formation, surface motility, adherence, and virulence. We showed the association between ppGpp and pathogenicity in A. baumannii for the first time; ppGpp may be a novel antivirulence target in A. baumannii.
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Affiliation(s)
- Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Maidul Islam
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Hye-Won Jung
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Daejin Lim
- Department of Microbiology, Chonnam National University Medical School, Gwangju South Korea
| | - Kwangsoo Kim
- Department of Microbiology, Chonnam National University Medical School, Gwangju South Korea
| | - Sung-Gwon Lee
- School of Biological Sciences and Technology, Chonnam National University, Gwangju South Korea
| | - Chungoo Park
- School of Biological Sciences and Technology, Chonnam National University, Gwangju South Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
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12
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Could the analgesic drugs, paracetamol and indomethacin, function as quorum sensing inhibitors? Microb Pathog 2021; 158:105097. [PMID: 34284088 DOI: 10.1016/j.micpath.2021.105097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/05/2020] [Accepted: 07/15/2021] [Indexed: 11/22/2022]
Abstract
The current failure of antimicrobials in treating life-threatening diseases, the high rate of multidrug resistant pathogens and the slow progress in the development of new antibiotics directed scientists to develop antivirulence drugs that targets quorum sensing (QS). In many microbes, QS acts as a communication system which control pathogenicity of microbes. Analgesics can be beneficial in controlling virulence traits of microbes and hence they may augment the efficacy of antimicrobials. In this study, two analgesics were screened for the inhibition of QS in Chromobacterium violaceum CV026 and their effects on virulence production in Pseudomonas aeruginosa PAO1 strain and clinical isolates of Acinetobacter baumannii were evaluated. The traits investigated were biofilm formation, pyocyanin and rhamnolipid production, twitching, swarming or surface associated motilities, production of protease, phospholipase and gelatinase enzymes and sensitivity to oxidative stress. Relative expression of abaI gene was calculated by performing qRT-PCR. Docking analysis of paracetamol as QSI (quorum sensing inhibitor) of AbaI and AbaR proteins was performed. Paracetamol inhibited QS in CV026, but indomethacin devoids anti-QS activity. Paracetamol inhibited virulence factors of PAO1. It strongly inhibited biofilm formation, and swarming by 66.4% and 57.1%, respectively. While, it moderately to slightly inhibited rhamnolipid, pyocyanin, gelatinase, resistance to oxidative stress, protease and twitching motility by 33.3%, 33.1% 17.5%, 9.1%, 8.7% and 7.7%, respectively. For A. baumannii, paracetamol strongly inhibited biofilm by 39.7-93% and phospholipase enzyme by 8.7-100%, reduced twitching and surface motility by 6.7-82.5% and 7.7-29.4%, respectively, And slightly reduced sensitivity to oxidative stress by 3.3-36.4%. Paracetamol at sub-MIC suppressed the expression of abaI gene by 32% in A. baumannii. Docking studies suggested that paracetamol can bind to AbaR and AbaI proteins and bind more to AbaR, hence it may act by inhibiting AHL signal reception. As a conclusion, paracetamol, beside its analgesic activity, has anti-QS activity and could be used in the eradication of P. aeruginosa and A. baumannii infections in combination with antibiotics.
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Blaschke U, Skiebe E, Wilharm G. Novel Genes Required for Surface-Associated Motility in Acinetobacter baumannii. Curr Microbiol 2021; 78:1509-1528. [PMID: 33666749 PMCID: PMC7997844 DOI: 10.1007/s00284-021-02407-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/10/2021] [Indexed: 01/28/2023]
Abstract
Acinetobacter baumannii is an opportunistic and increasingly multi-drug resistant human pathogen rated as a critical priority one pathogen for the development of new antibiotics by the WHO in 2017. Despite the lack of flagella, A. baumannii can move along wet surfaces in two different ways: via twitching motility and surface-associated motility. While twitching motility is known to depend on type IV pili, the mechanism of surface-associated motility is poorly understood. In this study, we established a library of 30 A. baumannii ATCC® 17978™ mutants that displayed deficiency in surface-associated motility. By making use of natural competence, we also introduced these mutations into strain 29D2 to differentiate strain-specific versus species-specific effects of mutations. Mutated genes were associated with purine/pyrimidine/folate biosynthesis (e.g. purH, purF, purM, purE), alarmone/stress metabolism (e.g. Ap4A hydrolase), RNA modification/regulation (e.g. methionyl-tRNA synthetase), outer membrane proteins (e.g. ompA), and genes involved in natural competence (comEC). All tested mutants originally identified as motility-deficient in strain ATCC® 17978™ also displayed a motility-deficient phenotype in 29D2. By contrast, further comparative characterization of the mutant sets of both strains regarding pellicle biofilm formation, antibiotic resistance, and virulence in the Galleria mellonella infection model revealed numerous strain-specific mutant phenotypes. Our studies highlight the need for comparative analyses to characterize gene functions in A. baumannii and for further studies on the mechanisms underlying surface-associated motility.
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Affiliation(s)
- Ulrike Blaschke
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany.
| | - Evelyn Skiebe
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany
| | - Gottfried Wilharm
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany.
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Mea HJ, Yong PVC, Wong EH. An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation. Microbiol Res 2021; 247:126722. [PMID: 33618061 DOI: 10.1016/j.micres.2021.126722] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022]
Abstract
The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.
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Affiliation(s)
- Hing Jian Mea
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Phelim Voon Chen Yong
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Eng Hwa Wong
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia.
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15
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Corral J, Pérez-Varela M, Barbé J, Aranda J. Direct interaction between RecA and a CheW-like protein is required for surface-associated motility, chemotaxis and the full virulence of Acinetobacter baumannii strain ATCC 17978. Virulence 2021; 11:315-326. [PMID: 32255384 PMCID: PMC7161683 DOI: 10.1080/21505594.2020.1748923] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen that causes multi-drug resistant infections mainly in immunocompromised patients. Although this gram-negative species lacks flagella, it is able to move over wet surfaces through a not well characterized type of movement known as surface-associated motility. In this study we demonstrate through the inactivation of the A1S_2813 gene (coding a CheW-like protein) and recA (coding a DNA damage repair and recombination protein) that both genes are involved in the surface-associated motility and chemotaxis of A. baumannii ATCC 17978 strain. In addition, we also point out that the lack of either RecA or CheW-like proteins reduces its virulence in the Caenorhabditis elegans and the Galleria mellonella animal models. Furthermore, we show through co-immunoprecipitation assays that the CheW-like protein and RecA interact and that this interaction is abolished by the introduction of the mutation S97A in one of the domains of CheW-like protein that is structurally conserved in Salmonella enterica and necessary for the RecA-CheW interaction in this bacterial species. Finally, we show that the replacement of the wild-type CheW-like protein by that presenting the S97A mutation impairs surface-associated motility, chemotaxis and virulence of A. baumannii strain ATCC 17978.
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Affiliation(s)
- Jordi Corral
- Departament de Genètica i Microbiologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - María Pérez-Varela
- Departament de Genètica i Microbiologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Jordi Barbé
- Departament de Genètica i Microbiologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Jesús Aranda
- Departament de Genètica i Microbiologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, Bellaterra, Spain
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Boone RL, Whitehead B, Avery TM, Lu J, Francis JD, Guevara MA, Moore RE, Chambers SA, Doster RS, Manning SD, Townsend SD, Dent L, Marshall D, Gaddy JA, Damo SM. Analysis of virulence phenotypes and antibiotic resistance in clinical strains of Acinetobacter baumannii isolated in Nashville, Tennessee. BMC Microbiol 2021; 21:21. [PMID: 33422000 PMCID: PMC7796680 DOI: 10.1186/s12866-020-02082-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 12/27/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Acinetobacter baumannii is a gram-negative bacterium which causes opportunistic infections in immunocompromised hosts. Genome plasticity has given rise to a wide range of strain variation with respect to antimicrobial resistance profiles and expression of virulence factors which lead to altered phenotypes associated with pathogenesis. The purpose of this study was to analyze clinical strains of A. baumannii for phenotypic variation that might correlate with virulence phenotypes, antimicrobial resistance patterns, or strain isolation source. We hypothesized that individual strain virulence phenotypes might be associated with anatomical site of isolation or alterations in susceptibility to antimicrobial interventions. METHODOLOGY A cohort of 17 clinical isolates of A. baumannii isolated from diverse anatomical sites were evaluated to ascertain phenotypic patterns including biofilm formation, hemolysis, motility, and antimicrobial resistance. Antibiotic susceptibility/resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin was determined. RESULTS Antibiotic resistance was prevalent in many strains including resistance to ampicillin-sulbactam, amikacin, ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, cefepime, gentamicin, levofloxacin, meropenem, piperacillin, trimethoprim-sulfamethoxazole, ticarcillin- K clavulanate, tetracyclin, and tobramycin. All strains tested induced hemolysis on agar plate detection assays. Wound-isolated strains of A. baumannii exhibited higher motility than strains isolated from blood, urine or Foley catheter, or sputum/bronchial wash. A. baumannii strains isolated from patient blood samples formed significantly more biofilm than isolates from wounds, sputum or bronchial wash samples. An inverse relationship between motility and biofilm formation was observed in the cohort of 17 clinical isolates of A. baumannii tested in this study. Motility was also inversely correlated with induction of hemolysis. An inverse correlation was observed between hemolysis and resistance to ticarcillin-k clavulanate, meropenem, and piperacillin. An inverse correlation was also observed between motility and resistance to ampicillin-sulbactam, ceftriaxone, ceftoxamine, ceftazidime, ciprofloxacin, or levofloxacin. CONCLUSIONS Strain dependent variations in biofilm and motility are associated with anatomical site of isolation. Biofilm and hemolysis production both have an inverse association with motility in the cohort of strains utilized in this study, and motility and hemolysis were inversely correlated with resistance to numerous antibiotics.
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Affiliation(s)
- Ranashia L Boone
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, TN, 37208, USA
| | - Briana Whitehead
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, TN, 37208, USA
| | - Tyra M Avery
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, TN, 37208, USA
| | - Jacky Lu
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jamisha D Francis
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Miriam A Guevara
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Rebecca E Moore
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | | | - Ryan S Doster
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center, A2200 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - Shannon D Manning
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | | | - Leon Dent
- Department of Pathology, Anatomy, and Physiology, Meharry Medical College, Nashville, TN, USA
- Trauma Services, Phoebe Putney Memorial Hospital, Albany, GA, USA
| | - Dana Marshall
- Department of Pathology, Anatomy, and Physiology, Meharry Medical College, Nashville, TN, USA
| | - Jennifer A Gaddy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center, A2200 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232, USA.
- Department of Veterans Affairs, Tennessee Valley Healthcare Systems, Nashville, TN, USA.
| | - Steven M Damo
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, TN, 37208, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
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Acinetobacter baumannii Targets Human Carcinoembryonic Antigen-Related Cell Adhesion Molecules (CEACAMs) for Invasion of Pneumocytes. mSystems 2020; 5:5/6/e00604-20. [PMID: 33361319 PMCID: PMC7762790 DOI: 10.1128/msystems.00604-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Multidrug-resistant Acinetobacter baumannii is regarded as a life-threatening pathogen mainly associated with nosocomial and community-acquired pneumonia. Here, we show that A. baumannii can bind the human carcinoembryonic antigen-related cell adhesion molecule (CEACAM) receptors CEACAM1, CEACAM5, and CEACAM6. This specific interaction enhances A. baumannii internalization in membrane-bound vacuoles, promptly decorated with Rab5, Rab7, and lipidated microtubule-associated protein light chain 3 (LC3). Dissecting intracellular signaling pathways revealed that infected pneumocytes trigger interleukin-8 (IL-8) secretion via the extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) signaling pathways for A. baumannii clearance. However, in CEACAM1-L-expressing cells, IL-8 secretion lasts only 24 h, possibly due to an A. baumannii-dependent effect on the CEACAM1-L intracellular domain. Conversely, the glycosylphosphatidylinositol-anchored CEACAM5 and CEACAM6 activate the c-Jun NH2-terminal kinase (JNK)1/2-Rubicon-NOX2 pathway, suggestive of LC3-associated phagocytosis. Overall, our data show for the first time novel mechanisms of adhesion to and invasion of pneumocytes by A. baumannii via CEACAM-dependent signaling pathways that eventually lead to bacterial killing. These findings suggest that CEACAM upregulation could put patients at increased risk of lower respiratory tract infection by A. baumannii IMPORTANCE This work shows for the first time that Acinetobacter baumannii binds to carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), CEACAM5, and CEACAM6. This binding significantly enhances A. baumannii internalization within alveolar host cell epithelia. Intracellular trafficking involves typical Rab5 and Rab7 vacuolar proteins as well as light chain 3 (LC3) and slowly progresses to bacterial killing by endosome acidification. CEACAM engagement by A. baumannii leads to distinct and specific downstream signaling pathways. The CEACAM1 pathway finely tunes interleukin-8 (IL-8) secretion, whereas CEACAM5 and CEACAM6 mediate LC3-associated phagocytosis. The present study provides new insights into A. baumannii-host interactions and could represent a promising therapeutic strategy to reduce pulmonary infections caused by this pathogen.
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Antibiofilm and antivirulence efficacy of myrtenol enhances the antibiotic susceptibility of Acinetobacter baumannii. Sci Rep 2020; 10:21975. [PMID: 33319862 PMCID: PMC7738676 DOI: 10.1038/s41598-020-79128-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 11/26/2020] [Indexed: 02/07/2023] Open
Abstract
Acinetobacter baumannii (AB) is rising as a human pathogen of critical priority worldwide as it is the leading cause of chronic opportunistic infections in healthcare settings and the condition is ineradicable with antibiotic therapy. AB possesses the ability to form biofilm on abiotic as well as biotic surfaces which plays a major role in its pathogenesis and resistance in clinical settings. Hence, the demand for an alternative therapy to combat the biofilm-associated infections is increasing. The present study explored the antibiofilm potential of myrtenol, a bicyclic monoterpene present in various plants against reference and clinical strains of AB. Myrtenol (200 μg/mL) exhibited a strong antibiofilm activity without exerting any harmful effect on growth and metabolic viability of AB strains. Microscopic analyses confirmed the reduction in the biofilm thickness and surface coverage upon myrtenol treatment. Especially, myrtenol was found to be effective in disrupting the mature biofilms of tested AB strains. Furthermore, myrtenol inhibited the biofilm-associated virulence factors of AB strains such as extracellular polysaccharide, cell surface hydrophobicity, oxidant resistance, swarming and twitching motility. Transcriptional analysis unveiled the suppression of the biofilm-associated genes such as bfmR, csuA/B, bap, ompA, pgaA, pgaC, and katE by myrtenol. Notably, myrtenol improved the susceptibility of AB strains towards conventional antibiotics such as amikacin, ciprofloxacin, gentamicin and trimethoprim. Thus, the present study demonstrates the therapeutic potential of myrtenol against biofilm-associated infections of AB.
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Tang J, Chen Y, Wang X, Ding Y, Sun X, Ni Z. Contribution of the AbaI/AbaR Quorum Sensing System to Resistance and Virulence of Acinetobacter baumannii Clinical Strains. Infect Drug Resist 2020; 13:4273-4281. [PMID: 33262621 PMCID: PMC7699449 DOI: 10.2147/idr.s276970] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Acinetobacter baumannii (A. baumannii) is one of the most important pathogens that cause serious nosocomial infections worldwide. However, there are few reports on the virulence of A. baumannii clinical isolates, and little is known about the mechanism regulating virulence and drug resistance. The aim of this study was to determine the prevalence of drug resistance and virulence profiles and explore features related to quorum sensing (QS). METHODS A total of 80 clinical A. baumannii isolates were collected from Jilin province of China from 2012 to 2017. We investigated these clinical isolates with respect to biofilm formation, surface motility, adherence, invasion into A549 human alveolar epithelial cells, and virulence to Galleria mellonella. We also explored the prevalence of the AbaI/AbaR QS system and its correlation with bacterial virulence and drug resistance. RESULTS The resistance rates of the isolates to 17 commonly used antibiotics were higher than 50%, and 75% of the isolates were multi-drug resistant. Approximately 95% (76/80) of the isolates showed the ability to form biofilms, of which 38 showed strong biofilm formation ability (+++). Only 5 strains showed strong surface-related motility. A high level of variability was found in adherence and invasion into A549 epithelial cells, and 16 isolates showed strong virulence to Galleria mellonella (none survived after 6 days of infection). Of the 61 isolates carrying abaI and abaR genes, 24 were found to produce N-acyl homoserine lactones (AHLs) detectable by biosensor bacteria. Correlation analysis revealed that abaI and abaR genes positively correlated with bacterial resistance rates. All strains showing obvious surface-related motility carried abaI and abaR genes and produced AHLs. The isolates with detectable QS systems also showed stronger invasiveness into A549 cells and pathogenicity toward G. mellonella than the QS-deficient isolates. CONCLUSION Our study demonstrates that the AbaI/AbaR QS system was widely distributed among the A. baumannii clinical isolates, was necessary for surface-related motility, and significantly correlated with drug resistance, invasion into epithelial cells, and virulence to G. mellonella.
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Affiliation(s)
- Jie Tang
- Department of Pathogen Biology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, Jilin130021, People’s Republic of China
| | - Yan Chen
- Department of Neurosurgery, The Second Hospital of Jilin University, Changchun, China130041, People’s Republic of China
| | - Xinlei Wang
- Department of Clinical Laboratory, The Second Hospital of Jilin University, Changchun130041, People’s Republic of China
| | - Yue Ding
- Department of Pathogen Biology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, Jilin130021, People’s Republic of China
| | - Xiaoyu Sun
- Department of Pathogen Biology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, Jilin130021, People’s Republic of China
| | - Zhaohui Ni
- Department of Pathogen Biology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, Jilin130021, People’s Republic of China
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Xanthopoulou K, Urrutikoetxea-Gutiérrez M, Vidal-Garcia M, Diaz de Tuesta Del Arco JL, Sánchez-Urtaza S, Wille J, Seifert H, Higgins PG, Gallego L. First Report of New Delhi Metallo- β-Lactamase-6 (NDM-6) in a Clinical Acinetobacter baumannii Isolate From Northern Spain. Front Microbiol 2020; 11:589253. [PMID: 33240245 PMCID: PMC7683408 DOI: 10.3389/fmicb.2020.589253] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/15/2020] [Indexed: 12/29/2022] Open
Abstract
The objective of this study was the phenotypic and genotypic characterization of a carbapenem resistant Acinetobacter baumannii (CRAB) isolate. The isolate, recovered in Northern Spain in 2019, was identified by MALDI-TOF to the species level. Antimicrobial susceptibility testing was performed using the Phoenix BD NMIC-502 Panel, E-test, and broth microdilution methods. The presence of a metallo-β-lactamase (MBL) was verified by PCR and immunochromatographic assays. The genetic location of the MBL was confirmed using S1-pulsed-field gel electrophoresis (S1-PFGE) followed by Southern blot hybridization. Whole genome sequencing (WGS) was completed using the Miseq and MinION platforms, followed by core-genome MLST (cgMLST) and seven-locus MLST analysis. The CRAB was assigned ST85 (Pasteur scheme) and ST957 (Oxford scheme) representing international clone (IC) 9 and harbored the intrinsic β-lactamase OXA-94 with ISAba1 upstream of it, and the MBL bla NDM-6. Hybridization experiments revealed that the bla NDM-6 was encoded on the chromosome. Using WGS the bla NDM-6 environment could be identified arranged in the following order: ISAba14, aphA6, ISAba125, bla NDM-6, ble MBL, trpF, dsbC, cutA, and ISAba14. Downstream, a 10,462 bp duplication was identified, including a second copy of bla NDM-6 in the following genetic composition: ISAba125, bla NDM-6, ble MBL, trpF, dsbC, cutA, and ISAba14. To our knowledge, this is the first description of bla NDM-6 in A. baumannii. The MBL was present in two copies in the chromosome in a new genetic environment associated with IS elements highlighting the contribution of mobile genetic elements in the dissemination of this gene.
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Affiliation(s)
- Kyriaki Xanthopoulou
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Mikel Urrutikoetxea-Gutiérrez
- Servicio de Microbiología y Control de Infección, Hospital Universitario Basurto, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Matxalen Vidal-Garcia
- Servicio de Microbiología y Control de Infección, Hospital Universitario Basurto, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - José-Luis Diaz de Tuesta Del Arco
- Servicio de Microbiología y Control de Infección, Hospital Universitario Basurto, Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Sandra Sánchez-Urtaza
- Department of Immunology, Microbiology, and Parasitology, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Bilbao, Spain
| | - Julia Wille
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, 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
| | - 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
| | - Lucía Gallego
- Department of Immunology, Microbiology, and Parasitology, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Bilbao, Spain
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21
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Abirami G, Durgadevi R, Velmurugan P, Ravi AV. Gene expressing analysis indicates the role of Pyrogallol as a novel antibiofilm and antivirulence agent against Acinetobacter baumannii. Arch Microbiol 2020; 203:251-260. [PMID: 32918098 DOI: 10.1007/s00203-020-02026-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/14/2020] [Accepted: 09/02/2020] [Indexed: 11/28/2022]
Abstract
Acinetobacter baumannii has emerged worldwide as a leading cause of hospital-acquired infections. Although A. baumannii was initially regarded to as a low-grade pathogen, evidence has been accumulated suggesting that A. baumannii infections are associated with increased mortality in critically ill patients. Here, we describe the efficacy of pyrogallol, a polyphenolic organic compound found in the galls and barks of various trees, which shows anti-biofilm and anti-virulence potential against A. baumannii. Pyrogallol shows concentration-based biofilm inhibition, as evidenced through light and confocal laser scanning microscopic analysis. The other virulence factors are protease, swarming motility, and extracellular polymeric substances that are also inhibited by pyrogallol. Through real-time PCR, it was found that pyrogallol downregulates expression of the biofilm and virulence-related ompA, bap, csuA/B, katE, pgaA, and pgaC genes. Furthermore, pyrogallol moderately inhibited the mature biofilms of A. baumannii in a concentration-dependent manner (5, 10, and 20 µg/ml). The present study reports that the anti-biofilm and anti-virulence potential of pyrogallol disrupts the biofilm formation, adherence of cells, and cell-to-cell signaling mechanism of A. baumannii. Thus, pyrogallol is a promising therapeutic agent for A. baumannii-related infections.
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Affiliation(s)
- Gurusamy Abirami
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Ravindran Durgadevi
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Palanivel Velmurugan
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Arumugam Veera Ravi
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India.
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Geisinger E, Mortman NJ, Dai Y, Cokol M, Syal S, Farinha A, Fisher DG, Tang AY, Lazinski DW, Wood S, Anthony J, van Opijnen T, Isberg RR. Antibiotic susceptibility signatures identify potential antimicrobial targets in the Acinetobacter baumannii cell envelope. Nat Commun 2020; 11:4522. [PMID: 32908144 PMCID: PMC7481262 DOI: 10.1038/s41467-020-18301-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/13/2020] [Indexed: 11/13/2022] Open
Abstract
A unique, protective cell envelope contributes to the broad drug resistance of the nosocomial pathogen Acinetobacter baumannii. Here we use transposon insertion sequencing to identify A. baumannii mutants displaying altered susceptibility to a panel of diverse antibiotics. By examining mutants with antibiotic susceptibility profiles that parallel mutations in characterized genes, we infer the function of multiple uncharacterized envelope proteins, some of which have roles in cell division or cell elongation. Remarkably, mutations affecting a predicted cell wall hydrolase lead to alterations in lipooligosaccharide synthesis. In addition, the analysis of altered susceptibility signatures and antibiotic-induced morphology patterns allows us to predict drug synergies; for example, certain beta-lactams appear to work cooperatively due to their preferential targeting of specific cell wall assembly machineries. Our results indicate that the pathogen may be effectively inhibited by the combined targeting of multiple pathways critical for envelope growth.
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Affiliation(s)
- Edward Geisinger
- Department of Biology, Northeastern University, Boston, MA, 02115, USA.
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Nadav J Mortman
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Yunfei Dai
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Murat Cokol
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Sapna Syal
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Andrew Farinha
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Delaney G Fisher
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Amy Y Tang
- Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - David W Lazinski
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Stephen Wood
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Jon Anthony
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Tim van Opijnen
- Biology Department, Boston College, Chestnut Hill, MA, 02467, USA
| | - Ralph R Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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23
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Characterization of RelA in Acinetobacter baumannii. J Bacteriol 2020; 202:JB.00045-20. [PMID: 32229531 DOI: 10.1128/jb.00045-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/26/2020] [Indexed: 12/21/2022] Open
Abstract
In response to nutrient depletion, the RelA and SpoT proteins generate the signaling molecule (p)ppGpp, which then controls a number of downstream effectors to modulate cell physiology. In Acinetobacter baumannii strain AB5075, a relA ortholog (ABUW_3302) was identified by a transposon insertion that conferred an unusual colony phenotype. An in-frame deletion in relA (ΔrelA) failed to produce detectable levels of ppGpp when amino acid starvation was induced with serine hydroxamate. The ΔrelA mutant was blocked from switching from the virulent opaque colony variant (VIR-O) to the avirulent translucent colony variant (AV-T), but the rate of AV-T to VIR-O switching was unchanged. In addition, the ΔrelA mutation resulted in a pronounced hypermotile phenotype on 0.35% agar plates. This hypermotility was dependent on the activation of a LysR regulator ABUW_1132, which was required for expression of AbaR, a LuxR family quorum-sensing regulator. In the ΔrelA mutant, ABUW_1132 was also required for the increased expression of an operon composed of the ABUW_3766-ABUW_3773 genes required for production of the surfactant-like lipopeptide acinetin 505. Additional phenotypes identified in the ΔrelA mutant included (i) cell elongation at high density, (ii) reduced formation of persister cells tolerant to colistin and rifampin, and (iii) decreased virulence in a Galleria mellonella model.IMPORTANCE Acinetobacter baumannii is a pathogen of worldwide importance. Due to the increasing prevalence of antibiotic resistance, these infections are becoming increasingly difficult to treat. New therapies are required to combat multidrug-resistant isolates. The role of RelA in A. baumannii is largely unknown. This study demonstrates that like in other bacteria, RelA controls a variety of functions, including virulence. Strategies to inhibit the activity of RelA and the resulting production of ppGpp could inhibit virulence and may represent a new therapeutic approach.
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Mutation of the Carboxy-Terminal Processing Protease in Acinetobacter baumannii Affects Motility, Leads to Loss of Membrane Integrity, and Reduces Virulence. Pathogens 2020; 9:pathogens9050322. [PMID: 32357487 PMCID: PMC7281292 DOI: 10.3390/pathogens9050322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/13/2020] [Accepted: 04/24/2020] [Indexed: 01/17/2023] Open
Abstract
Motility plays an essential role in the host–parasite relationship of pathogenic bacteria, and is often associated with virulence. While many pathogenic bacteria use flagella for locomotion, Acinetobacter baumannii strains do not have flagella, but have other features that aid in their motility. To study the genes involved in motility, transposon mutagenesis was performed to construct A. baumannii mutant strains. Mutant strain MR14 was found to have reduced motility, compared to wild-type ATCC 17978. NCBI BLAST analysis revealed that the Tn10 transposon in the MR14 genome is integrated into the gene that encodes for carboxy-terminal processing protease (Ctp). Additionally, MR14 exhibits a mucoidy, sticky phenotype as the result of increased extracellular DNA (eDNA) caused by bacterial autolysis. Transmission and scanning electron microscopy revealed cytoplasmic content leaving the cell and multiple cell membrane depressions, respectively. MR14 showed higher sensitivity to environmental stressors. Mutation of the ctp gene reduced invasion and adhesion of A. baumannii to airway epithelial cells, potentially due to increased hydrophobicity. In the zebrafish model of infection, MR14 increased the survival rate by 40% compared to the wild-type. Taken together, the ctp gene in A. baumannii has a pivotal role in maintaining membrane integrity, adaptation to environmental stress, and controlling virulence.
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Seleem NM, Abd El Latif HK, Shaldam MA, El-Ganiny A. Drugs with new lease of life as quorum sensing inhibitors: for combating MDR Acinetobacter baumannii infections. Eur J Clin Microbiol Infect Dis 2020; 39:1687-1702. [PMID: 32328851 PMCID: PMC7180647 DOI: 10.1007/s10096-020-03882-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/27/2020] [Indexed: 12/21/2022]
Abstract
The emergence of multidrug-resistant (MDR) strains is a major health problem worldwide. There is an urgent need for novel strategies to combat bacterial infections caused by MDR strains like Pseudomonas aeruginosa and Acinetobacter baumannii. Quorum sensing (QS) is a critical communication system in bacterial community controlling survival and virulence. The awareness of the importance of QS in bacterial infections has stimulated research to identify QS inhibitors (QSIs) to defeat microbes. In this study, four FDA-approved drugs (besides azithromycin as positive QSI) were tested for potential QS inhibition against clinical A. baumannii isolates and P. aeruginosa (PAO1) standard strain. The inhibitory effect of these drugs on virulence factors of both microbes has been investigated. The studied virulence factors include biofilm formation, twitching and swarming motilities, proteolytic enzyme production, and resistance to oxidative stress. The four tested drugs (erythromycin, levamisole, chloroquine, and propranolol) inhibited QS in Chromobacterium violaceum by 84, 72, 55.1, and 37.3%, respectively. They also significantly inhibited virulence factors in both PAO1 and A. baumannii at sub-inhibitory concentrations. These findings were confirmed by qRT-PCR and mice mortality test, where tested drugs highly repressed the expression of abaI gene and showed significantly improved mice survival rates. In addition, molecular docking studies against AbaI and AbaR proteins of QS system in A. baumannii revealed the potential inhibition of QS by tested drugs. Beside their known activities, the tested drugs could be given new life as QSIs to combat A. baumannii nosocomial infections (alone or in combination with antimicrobials).
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Affiliation(s)
- Noura M Seleem
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Hemat K Abd El Latif
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Moataz A Shaldam
- Department of Medicinal Chemistry, Faculty of Pharmacy, Kafr-elsheikh University, Kafr El Sheikh, 33516, Egypt
| | - Amira El-Ganiny
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt.
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26
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Ayoub Moubareck C, Hammoudi Halat D. Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen. Antibiotics (Basel) 2020; 9:antibiotics9030119. [PMID: 32178356 PMCID: PMC7148516 DOI: 10.3390/antibiotics9030119] [Citation(s) in RCA: 201] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/01/2020] [Accepted: 03/02/2020] [Indexed: 12/12/2022] Open
Abstract
Being a multidrug-resistant and an invasive pathogen, Acinetobacter baumannii is one of the major causes of nosocomial infections in the current healthcare system. It has been recognized as an agent of pneumonia, septicemia, meningitis, urinary tract and wound infections, and is associated with high mortality. Pathogenesis in A. baumannii infections is an outcome of multiple virulence factors, including porins, capsules, and cell wall lipopolysaccharide, enzymes, biofilm production, motility, and iron-acquisition systems, among others. Such virulence factors help the organism to resist stressful environmental conditions and enable development of severe infections. Parallel to increased prevalence of infections caused by A. baumannii, challenging and diverse resistance mechanisms in this pathogen are well recognized, with major classes of antibiotics becoming minimally effective. Through a wide array of antibiotic-hydrolyzing enzymes, efflux pump changes, impermeability, and antibiotic target mutations, A. baumannii models a unique ability to maintain a multidrug-resistant phenotype, further complicating treatment. Understanding mechanisms behind diseases, virulence, and resistance acquisition are central to infectious disease knowledge about A. baumannii. The aims of this review are to highlight infections and disease-producing factors in A. baumannii and to touch base on mechanisms of resistance to various antibiotic classes.
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Affiliation(s)
- Carole Ayoub Moubareck
- College of Natural and Health Sciences, Zayed University, Dubai P.O. Box 144534, UAE
- Correspondence: ; Tel.: +971-4-402-1745
| | - Dalal Hammoudi Halat
- Department of Pharmaceutical Sciences, School of Pharmacy, Lebanese International University, Beirut, Bekaa Campuses 1103, Lebanon;
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Becerra-Rivera VA, Arteaga A, Leija A, Hernández G, Dunn MF. Polyamines produced by Sinorhizobium meliloti Rm8530 contribute to symbiotically relevant phenotypes ex planta and to nodulation efficiency on alfalfa. MICROBIOLOGY-SGM 2020; 166:278-287. [PMID: 31935179 DOI: 10.1099/mic.0.000886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In nitrogen-fixing rhizobia, emerging evidence shows significant roles for polyamines in growth and abiotic stress resistance. In this work we show that a polyamine-deficient ornithine decarboxylase null mutant (odc2) derived from Sinorhizobium meliloti Rm8530 had significant phenotypic differences from the wild-type, including greatly reduced production of exopolysaccharides (EPS; ostensibly both succinoglycan and galactoglucan), increased sensitivity to oxidative stress and decreased swimming motility. The introduction of the odc2 gene borne on a plasmid into the odc2 mutant restored wild-type phenotypes for EPS production, growth under oxidative stress and swimming. The production of calcofluor-binding EPS (succinoglycan) by the odc2 mutant was also completely or mostly restored in the presence of exogenous spermidine (Spd), norspermidine (NSpd) or spermine (Spm). The odc2 mutant formed about 25 % more biofilm than the wild-type, and its ability to form biofilm was significantly inhibited by exogenous Spd, NSpd or Spm. The odc2 mutant formed a less efficient symbiosis with alfalfa, resulting in plants with significantly less biomass and height, more nodules but less nodule biomass, and 25 % less nitrogen-fixing activity. Exogenously supplied Put was not able to revert these phenotypes and caused a similar increase in plant height and dry weight in uninoculated plants and in those inoculated with the wild-type or odc2 mutant. We discuss ways in which polyamines might affect the phenotypes of the odc2 mutant.
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Affiliation(s)
- Victor A Becerra-Rivera
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
| | - Alejandra Arteaga
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
| | - Alfonso Leija
- Programa de Genómica Funcional de Eucariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
| | - Georgina Hernández
- Programa de Genómica Funcional de Eucariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
| | - Michael F Dunn
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
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28
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Cosgaya C, Ratia C, Marí-Almirall M, Rubio L, Higgins PG, Seifert H, Roca I, Vila J. In vitro and in vivo Virulence Potential of the Emergent Species of the Acinetobacter baumannii (Ab) Group. Front Microbiol 2019; 10:2429. [PMID: 31708900 PMCID: PMC6821683 DOI: 10.3389/fmicb.2019.02429] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/08/2019] [Indexed: 01/30/2023] Open
Abstract
The increased use of molecular identification methods and mass spectrometry has revealed that Acinetobacter spp. of the A. baumannii (Ab) group other than A. baumannii are increasingly being recovered from human samples and may pose a health challenge if neglected. In this study 76 isolates of 5 species within the Ab group (A. baumannii n = 16, A. lactucae n = 12, A. nosocomialis n = 16, A. pittii n = 20, and A. seifertii n = 12), were compared in terms of antimicrobial susceptibility, carriage of intrinsic resistance genes, biofilm formation, and the ability to kill Caenorhabditis elegans in an infection assay. In agreement with previous studies, antimicrobial resistance was common among A. baumannii while all other species were generally more susceptible. Carriage of genes encoding different efflux pumps was frequent in all species and the presence of intrinsic class D β-lactamases was reported in A. baumannii, A. lactucae (heterotypic synonym of A. dijkshoorniae) and A. pittii but not in A. nosocomialis and A. seifertii. A. baumannii and A. nosocomialis presented weaker pathogenicity in our in vitro and in vivo models than A. seifertii, A. pittii and, especially, A. lactucae. Isolates from the former species showed decreased biofilm formation and required a longer time to kill C. elegans nematodes. These results suggest relevant differences in terms of antibiotic susceptibility patterns among the members of the Ab group as well as highlight a higher pathogenicity potential for the emerging species of the group in this particular model. Nevertheless, the impact of such potential in the human host still remains to be determined.
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Affiliation(s)
- Clara Cosgaya
- ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain
| | - Carlos Ratia
- ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain
| | | | - Laia Rubio
- ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain
| | - Paul G Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Bonn, Germany
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Bonn, Germany
| | - Ignasi Roca
- ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain
| | - Jordi Vila
- ISGlobal, Hospital Clínic - University of Barcelona, Barcelona, Spain
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29
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Du GF, Zheng YD, Chen J, He QY, Sun X. Novel Mechanistic Insights into Bacterial Fluoroquinolone Resistance. J Proteome Res 2019; 18:3955-3966. [DOI: 10.1021/acs.jproteome.9b00410] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Gao-Fei Du
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Yun-Dan Zheng
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Jing Chen
- Department of Clinical Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou 510632, China
| | - Qing-Yu He
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Xuesong Sun
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
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30
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Abstract
The genomes of Acinetobacter baumannii tell us stories about horizontal gene transfer (HGT) events that steadily drive the evolution of this nosocomial pathogen toward multidrug resistance. Natural transformation competence constitutes one of the several possible pathways that mediate HGT in A. baumannii. Here, we describe and discuss the methods for studying DNA uptake in A. baumannii via natural transformation.
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Dolzani L, Milan A, Scocchi M, Lagatolla C, Bressan R, Benincasa M. Sub-MIC effects of a proline-rich antibacterial peptide on clinical isolates of Acinetobacter baumannii. J Med Microbiol 2019; 68:1253-1265. [PMID: 31215857 DOI: 10.1099/jmm.0.001028] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION Acinetobacter baumannii is one of the most important nosocomial pathogens, mainly due to its ability to accumulate antibiotic-resistances and to persist in the hospital environment - characteristics related to biofilm production. It is well-known that A. baumannii is inhibited by the proline-rich peptide Bac7(1-35), but its putative effects at sub-MICs were never considered. AIMS We examined the sub-MIC effect of Bac7(1-35) on the growth rate, resistance induction and some A. baumannii features linked to virulence. METHODOLOGY Growth kinetics in the presence of sub-MICs of Bac7(1-35) were evaluated spectrophotometrically. Peptide uptake was quantified by cytometric analysis. The ability of Bac7(1-35) to interfere with biofilm production was investigated by the crystal violet method and confocal microscopy. Bacterial motility was observed at the interphase between a layer of a semi-solid medium and the polystyrene bottom of a Petri dish. The induction of resistance was evaluated after serial passages with sub-MICs of the peptide. RESULTS Although the MIC of Bac7(1-35) was between 2-4 µM for all tested strains, its effect on the growth rate at sub-MICs was strain-dependent and correlated with the amount of peptide internalized by each strain. Sub-MICs of Bac7(1-35) induced a strongly strain-dependent effect on biofilm formation and reduced motility in almost all strains, but interestingly the peptide did not induce resistance. CONCLUSION Bac7(1-35) is internalized into A. baumannii and is able to inhibit biofilm formation and bacterial motility, without inducing resistance. This study stresses the importance of considering possible effects that antimicrobials could have at sub-MICs, mimicking a common condition during antibiotic treatment.
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Affiliation(s)
- Lucilla Dolzani
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Annalisa Milan
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Marco Scocchi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | | | - Raffaela Bressan
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Monica Benincasa
- Department of Life Sciences, University of Trieste, Trieste, Italy
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Roles of Efflux Pumps from Different Superfamilies in the Surface-Associated Motility and Virulence of Acinetobacter baumannii ATCC 17978. Antimicrob Agents Chemother 2019; 63:AAC.02190-18. [PMID: 30642939 DOI: 10.1128/aac.02190-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/07/2019] [Indexed: 02/06/2023] Open
Abstract
Although the relationship between Acinetobacter baumannii efflux pumps and antimicrobial resistance is well documented, less is known about the involvement of these proteins in the pathogenicity of this nosocomial pathogen. In previous work, we identified the AbaQ major facilitator superfamily (MFS) efflux pump and demonstrated its participation in the motility and virulence of A. baumannii In the present study, we examined the role in these processes of A. baumannii transporters belonging to different superfamilies of efflux pumps. Genes encoding known or putative permeases belonging to efflux pump superfamilies other than the MFS were selected, and the corresponding knockouts were constructed. The antimicrobial susceptibilities of these mutants were consistent with previously reported data. In mutants of A. baumannii strain ATCC 17978 carrying inactivated genes encoding the efflux pumps A1S_2736 (resistance nodulation division [RND]), A1S_3371 (multidrug and toxic compound extrusion [MATE]), and A1S_0710 (small multidrug resistance [SMR]), as well as the newly described ATP-binding cassette (ABC) permeases A1S_1242 and A1S_2622, both surface-associated motility and virulence were reduced compared to the parental strain. However, inactivation of the genes encoding the known ABC permeases A1S_0536 and A1S_1535, the newly identified putative ABC permeases A1S_0027 and A1S_1057, or the proteobacterial antimicrobial compound efflux (PACE) transporters A1S_1503 and A1S_2063 had no effects on bacterial motility or virulence. Our results demonstrate the involvement of antimicrobial transporters belonging at least to five of the six known efflux pump superfamilies in both surface-associated motility and virulence in A. baumannii ATCC 17978.
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Conley ZC, Carlson-Banning KM, Carter AG, de la Cova A, Song Y, Zechiedrich L. Sugar and iron: Toward understanding the antibacterial effect of ciclopirox in Escherichia coli. PLoS One 2019; 14:e0210547. [PMID: 30633761 PMCID: PMC6329577 DOI: 10.1371/journal.pone.0210547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/27/2018] [Indexed: 12/11/2022] Open
Abstract
New antibiotics are needed against antibiotic-resistant gram-negative bacteria. The repurposed antifungal drug, ciclopirox, equally blocks antibiotic-susceptible or multidrug-resistant Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae clinical isolates, indicating that it is not affected by existing resistance mechanisms. Toward understanding how ciclopirox blocks growth, we screened E. coli mutant strains and found that disruption of genes encoding products involved in galactose salvage, enterobacterial common antigen synthesis, and transport of the iron binding siderophore, enterobactin, lowered the minimum inhibitory concentration of ciclopirox needed to block growth of the mutant compared to the isogenic parent strain. We found that ciclopirox induced enterobactin production and that this effect is strongly affected by the deletion of the galactose salvage genes encoding UDP-galactose 4-epimerase, galE, or galactose-1-phosphate uridylyltransferase, galT. As disruption of ECA synthesis activates the regulation of capsular synthesis (Rcs) phosphorelay, which inhibits bacterial swarming and promotes biofilm development, we test whether ciclopirox prevents activation of the Rcs pathway. Sub-inhibitory concentrations of ciclopirox increased swarming of the E. coli laboratory K12 strain BW25113 but had widely varying effects on swarming or surface motility of clinical isolate E. coli, A. baumannii, and K. pneumoniae. There was no effect of ciclopirox on biofilm production, suggesting it does not target Rcs. Altogether, our data suggest ciclopirox-mediated alteration of lipopolysaccharides stimulates enterobactin production and affects bacterial swarming.
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Affiliation(s)
- Zachary C. Conley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kimberly M. Carlson-Banning
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ashley G. Carter
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alejandro de la Cova
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Yongcheng Song
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lynn Zechiedrich
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America
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34
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Blaschke U, Suwono B, Zafari S, Ebersberger I, Skiebe E, Jeffries CM, Svergun DI, Wilharm G. Recombinant production of A1S_0222 from Acinetobacter baumannii ATCC 17978 and confirmation of its DNA-(adenine N6)-methyltransferase activity. Protein Expr Purif 2018; 151:78-85. [DOI: 10.1016/j.pep.2018.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/07/2018] [Accepted: 06/13/2018] [Indexed: 11/16/2022]
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Abstract
Most of the phylogenetic diversity of life is found in bacteria and archaea, and is reflected in the diverse metabolism and functions of bacterial and archaeal polyamines. The polyamine spermidine was probably present in the last universal common ancestor, and polyamines are known to be necessary for critical physiological functions in bacteria, such as growth, biofilm formation, and other surface behaviors, and production of natural products, such as siderophores. There is also phylogenetic diversity of function, indicated by the role of polyamines in planktonic growth of different species, ranging from absolutely essential to entirely dispensable. However, the cellular molecular mechanisms responsible for polyamine function in bacterial growth are almost entirely unknown. In contrast, the molecular mechanisms of essential polyamine functions in archaea are better understood: covalent modification by polyamines of translation factor aIF5A and the agmatine modification of tRNAIle As with bacterial hyperthermophiles, archaeal thermophiles require long-chain and branched polyamines for growth at high temperatures. For bacterial species in which polyamines are essential for growth, it is still unknown whether the molecular mechanisms underpinning polyamine function involve covalent or noncovalent interactions. Understanding the cellular molecular mechanisms of polyamine function in bacterial growth and physiology remains one of the great challenges for future polyamine research.
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Affiliation(s)
- Anthony J Michael
- From the Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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36
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Knight DB, Rudin SD, Bonomo RA, Rather PN. Acinetobacter nosocomialis: Defining the Role of Efflux Pumps in Resistance to Antimicrobial Therapy, Surface Motility, and Biofilm Formation. Front Microbiol 2018; 9:1902. [PMID: 30186249 PMCID: PMC6111201 DOI: 10.3389/fmicb.2018.01902] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/27/2018] [Indexed: 11/26/2022] Open
Abstract
Acinetobacter nosocomialis is a member of the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex. Increasingly, reports are emerging of the pathogenic profile and multidrug resistance (MDR) phenotype of this species. To define novel therapies to overcome resistance, we queried the role of the major efflux pumps in A. nosocomialis strain M2 on antimicrobial susceptibility profiles. A. nosocomialis strains with the following mutations were engineered by allelic replacement; ΔadeB, ΔadeJ, and ΔadeB/adeJ. In these isogenic strains, we show that the ΔadeJ mutation increased susceptibility to beta-lactams, beta-lactam/beta-lactamase inhibitors, chloramphenicol, monobactam, tigecycline, and trimethoprim. The ΔadeB mutation had a minor effect on resistance to certain beta-lactams, rifampicin and tigecycline. In addition, the ΔadeJ mutation resulted in a significant decrease in surface motility and a minor decrease in biofilm formation. Our results indicate that the efflux pump, AdeIJK, has additional roles outside of antibiotic resistance in A. nosocomialis.
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Affiliation(s)
- Daniel B Knight
- Research Service, Atlanta Veterans Affairs Medical Center, Decatur, GA, United States
| | - Susan D Rudin
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States.,Department of Medicine, Pharmacology and Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Case Western Reserve University Veterans Affairs Center for Antimicrobial Resistance (Case-VA CARES), Cleveland, OH, United States
| | - Robert A Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States.,Department of Medicine, Pharmacology and Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Case Western Reserve University Veterans Affairs Center for Antimicrobial Resistance (Case-VA CARES), Cleveland, OH, United States
| | - Philip N Rather
- Research Service, Atlanta Veterans Affairs Medical Center, Decatur, GA, United States.,Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States
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37
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Subhadra B, Kim J, Kim DH, Woo K, Oh MH, Choi CH. Local Repressor AcrR Regulates AcrAB Efflux Pump Required for Biofilm Formation and Virulence in Acinetobacter nosocomialis. Front Cell Infect Microbiol 2018; 8:270. [PMID: 30131944 PMCID: PMC6090078 DOI: 10.3389/fcimb.2018.00270] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/19/2018] [Indexed: 12/28/2022] Open
Abstract
Multidrug efflux systems contribute to antimicrobial resistance and pathogenicity in bacteria. Here, we report the identification and characterization of a transcriptional regulator AcrR controlling the yet uncharacterized multidrug efflux pump, AcrAB in Acinetobacter nosocomialis. In silico analysis revealed that the homologs of AcrR and AcrAB are reported in the genomes of many other bacterial species. We confirmed that the genes encoding the AcrAB efflux pump, acrA and acrB forms a polycistronic operon which is under the control of acrR gene upstream of acrA. Bioinformatic analysis indicated the presence of AcrR binding motif in the promoter region of acrAB operon and the specific binding of AcrR was confirmed by electrophoretic mobility shift assay (EMSA). The EMSA data showed that AcrR binds to −89 bp upstream of the start codon of acrA. The mRNA expression analysis depicted that the expression of acrA and acrB genes are elevated in the deletion mutant compared to that in the wild type confirming that AcrR acts as a repressor of acrAB operon in A. nosocomialis. The deletion of acrR resulted in increased motility, biofilm/pellicle formation and invasion in A. nosocomialis. We further analyzed the role of AcrR in A. nosocomialis pathogenesis in vivo using murine model and it was shown that acrR mutant is highly virulent inducing severe infection in mouse leading to host death. In addition, the intracellular survival rate of acrR mutant was higher compared to that of wild type. Our data demonstrates that AcrR functions as an important regulator of AcrAB efflux pump and is associated with several phenotypes such as motility, biofilm/pellicle formation and pathogenesis in A. nosocomialis.
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Affiliation(s)
- Bindu Subhadra
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, Daejeon, South Korea
| | - Jaeseok Kim
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, Daejeon, South Korea
| | - Dong Ho Kim
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, Daejeon, South Korea
| | - Kyungho Woo
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, Daejeon, South Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science, Dankook University, Cheonan, South Korea
| | - Chul Hee Choi
- Department of Microbiology and Medical Science, Chungnam National University School of Medicine, Daejeon, South Korea
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38
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Abdollahi S, Rasooli I, Mousavi Gargari SL. The role of TonB-dependent copper receptor in virulence of Acinetobacter baumannii. INFECTION GENETICS AND EVOLUTION 2018; 60:181-190. [PMID: 29505819 DOI: 10.1016/j.meegid.2018.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 02/11/2018] [Accepted: 03/01/2018] [Indexed: 12/15/2022]
Abstract
Acinetobacter baumannii is an opportunistic gram negative pathogen that can adhere to different surfaces and cause different nosocomial infections. To investigate the role of TonB-dependent copper receptor, an outer membrane protein, in virulence of A. baumannii, we deleted this receptor from A. baumannii chromosome. There was a significant decrease in biofilm formation by copper receptor deficient mutant strain. Similarly, the adherence to human epithelial cell and the hydrophobicity were declined. The survival rate of the mutant strain in human sera was reduced while no change was observed in motility of strains. In murine pneumonia model, the bacterial lethal dose 0 (LD0), LD50 and LD100 were increased for mutant strain. Moreover, in vivo and in vitro experiments revealed changes in growth rate and dissemination of mutant strain; so that the bacterial load of the mutant was significantly reduced in the spleen and lung. The findings suggest a critical role for TonB-dependent copper receptor in virulence of A. baumannii.
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Affiliation(s)
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center, Shahed University, Tehran, Iran.
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39
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Lowe-Power TM, Hendrich CG, von Roepenack-Lahaye E, Li B, Wu D, Mitra R, Dalsing BL, Ricca P, Naidoo J, Cook D, Jancewicz A, Masson P, Thomma B, Lahaye T, Michael AJ, Allen C. Metabolomics of tomato xylem sap during bacterial wilt reveals Ralstonia solanacearum produces abundant putrescine, a metabolite that accelerates wilt disease. Environ Microbiol 2017; 20:1330-1349. [PMID: 29215193 DOI: 10.1111/1462-2920.14020] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/29/2017] [Accepted: 12/03/2017] [Indexed: 12/20/2022]
Abstract
Ralstonia solanacearum thrives in plant xylem vessels and causes bacterial wilt disease despite the low nutrient content of xylem sap. We found that R. solanacearum manipulates its host to increase nutrients in tomato xylem sap, enabling it to grow better in sap from infected plants than in sap from healthy plants. Untargeted GC/MS metabolomics identified 22 metabolites enriched in R. solanacearum-infected sap. Eight of these could serve as sole carbon or nitrogen sources for R. solanacearum. Putrescine, a polyamine that is not a sole carbon or nitrogen source for R. solanacearum, was enriched 76-fold to 37 µM in R. solanacearum-infected sap. R. solanacearum synthesized putrescine via a SpeC ornithine decarboxylase. A ΔspeC mutant required ≥ 15 µM exogenous putrescine to grow and could not grow alone in xylem even when plants were treated with putrescine. However, co-inoculation with wildtype rescued ΔspeC growth, indicating R. solanacearum produced and exported putrescine to xylem sap. Intriguingly, treating plants with putrescine before inoculation accelerated wilt symptom development and R. solanacearum growth and systemic spread. Xylem putrescine concentration was unchanged in putrescine-treated plants, so the exogenous putrescine likely accelerated disease indirectly by affecting host physiology. These results indicate that putrescine is a pathogen-produced virulence metabolite.
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Affiliation(s)
- Tiffany M Lowe-Power
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Connor G Hendrich
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Edda von Roepenack-Lahaye
- Leibniz Institute of Plant Biochemistry, Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Tübingen, Germany
| | - Bin Li
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Dousheng Wu
- Leibniz Institute of Plant Biochemistry, Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Tübingen, Germany
| | - Raka Mitra
- Department of Biology, Carleton College, Northfield, MN 55057, USA
| | - Beth L Dalsing
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Patrizia Ricca
- Leibniz Institute of Plant Biochemistry, Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Tübingen, Germany
| | - Jacinth Naidoo
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - David Cook
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Amy Jancewicz
- Department of Genetics, University of Wisconsin, Madison, Madison, WI 53706, USA
| | - Patrick Masson
- Department of Genetics, University of Wisconsin, Madison, Madison, WI 53706, USA
| | - Bart Thomma
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Thomas Lahaye
- Leibniz Institute of Plant Biochemistry, Zentrum für Molekularbiologie der Pflanzen (ZMBP), Universität Tübingen, Tübingen, Germany
| | - Anthony J Michael
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin - Madison, Madison, WI 53706, USA
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40
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Harding CM, Hennon SW, Feldman MF. Uncovering the mechanisms of Acinetobacter baumannii virulence. Nat Rev Microbiol 2017; 16:91-102. [PMID: 29249812 DOI: 10.1038/nrmicro.2017.148] [Citation(s) in RCA: 542] [Impact Index Per Article: 77.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Acinetobacter baumannii is a nosocomial pathogen that causes ventilator-associated as well as bloodstream infections in critically ill patients, and the spread of multidrug-resistant Acinetobacter strains is cause for concern. Much of the success of A. baumannii can be directly attributed to its plastic genome, which rapidly mutates when faced with adversity and stress. However, fundamental virulence mechanisms beyond canonical drug resistance were recently uncovered that enable A. baumannii and, to a limited extent, other medically relevant Acinetobacter species to successfully thrive in the health-care environment. In this Review, we explore the molecular features that promote environmental persistence, including desiccation resistance, biofilm formation and motility, and we discuss the most recently identified virulence factors, such as secretion systems, surface glycoconjugates and micronutrient acquisition systems that collectively enable these pathogens to successfully infect their hosts.
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Affiliation(s)
- Christian M Harding
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA.,VaxNewMo LLC, St. Louis, Missouri 63108, USA
| | - Seth W Hennon
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA.,VaxNewMo LLC, St. Louis, Missouri 63108, USA
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41
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Wilharm G, Skiebe E, Higgins PG, Poppel MT, Blaschke U, Leser S, Heider C, Heindorf M, Brauner P, Jäckel U, Böhland K, Cuny C, Łopińska A, Kaminski P, Kasprzak M, Bochenski M, Ciebiera O, Tobółka M, Żołnierowicz KM, Siekiera J, Seifert H, Gagné S, Salcedo SP, Kaatz M, Layer F, Bender JK, Fuchs S, Semmler T, Pfeifer Y, Jerzak L. Relatedness of wildlife and livestock avian isolates of the nosocomial pathogenAcinetobacter baumanniito lineages spread in hospitals worldwide. Environ Microbiol 2017; 19:4349-4364. [DOI: 10.1111/1462-2920.13931] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 09/14/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Gottfried Wilharm
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Evelyn Skiebe
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Paul G. Higgins
- Institute for Medical Microbiology, Immunology and Hygiene; University of Cologne; Cologne D-50935 Germany
- Partner site Bonn-Cologne; German Centre for Infection Research (DZIF); Germany
| | - Marie T. Poppel
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Ulrike Blaschke
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Sarah Leser
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Christine Heider
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Magdalena Heindorf
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Paul Brauner
- Federal Institute for Occupational Safety and Health (BAuA), Nöldnerstr. 40-42; Berlin D-10317 Germany
| | - Udo Jäckel
- Federal Institute for Occupational Safety and Health (BAuA), Nöldnerstr. 40-42; Berlin D-10317 Germany
| | | | - Christiane Cuny
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Andżelina Łopińska
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
| | - Piotr Kaminski
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
- Nicolaus Copernicus University in Toruń, Collegium Medicum in Bydgoszcz, Faculty of Medicine; Department of Medical Biology, Department of Ecology and Environmental Protection; M. Skłodowska-Curie St. 9, PL 85-094 Bydgoszcz Poland
| | - Mariusz Kasprzak
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
| | - Marcin Bochenski
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
| | - Olaf Ciebiera
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
| | - Marcin Tobółka
- Institute of Zoology; Poznań University of Life Sciences, Wojska Polskiego 71C; 60-625 Poznań Poland
| | - Katarzyna M. Żołnierowicz
- Institute of Zoology; Poznań University of Life Sciences, Wojska Polskiego 71C; 60-625 Poznań Poland
| | | | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene; University of Cologne; Cologne D-50935 Germany
- Partner site Bonn-Cologne; German Centre for Infection Research (DZIF); Germany
| | - Stéphanie Gagné
- Laboratory of Molecular Microbiology and Structural Biochemistry; University of Lyon, CNRS UMR 5086; Lyon F-69367 France
| | - Suzana P. Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry; University of Lyon, CNRS UMR 5086; Lyon F-69367 France
| | - Michael Kaatz
- Vogelschutzwarte Storchenhof Loburg e.V, Chausseestr. 18; Loburg D-39279 Germany
| | - Franziska Layer
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Jennifer K. Bender
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Stephan Fuchs
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | | | - Yvonne Pfeifer
- Wernigerode Branch; Robert Koch Institute, Burgstr. 37; Wernigerode D-38855 Germany
| | - Leszek Jerzak
- Faculty of Biological Sciences; University of Zielona Góra, Prof. Z. Szafrana Street 1; 65-561 Zielona Góra Poland
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42
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Repizo GD, Viale AM, Borges V, Cameranesi MM, Taib N, Espariz M, Brochier-Armanet C, Gomes JP, Salcedo SP. The Environmental Acinetobacter baumannii Isolate DSM30011 Reveals Clues into the Preantibiotic Era Genome Diversity, Virulence Potential, and Niche Range of a Predominant Nosocomial Pathogen. Genome Biol Evol 2017; 9:2292-2307. [PMID: 28934377 PMCID: PMC5604120 DOI: 10.1093/gbe/evx162] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2017] [Indexed: 12/20/2022] Open
Abstract
Acinetobacter baumannii represents nowadays an important nosocomial opportunistic pathogen whose reservoirs outside the clinical setting are obscure. Here, we traced the origins of the collection strain A. baumannii DSM30011 to an isolate first reported in 1944, obtained from the enriched microbiota responsible of the aerobic decomposition of the resinous desert shrub guayule. Whole-genome sequencing and phylogenetic analysis based on core genes confirmed DSM30011 affiliation to A. baumannii. Comparative studies with 32 complete A. baumannii genomes revealed the presence of 12 unique accessory chromosomal regions in DSM30011 including five encompassing phage-related genes, five containing toxin genes of the type-6 secretion system, and one with an atypical CRISPRs/cas cluster. No antimicrobial resistance islands were identified in DSM30011 agreeing with a general antimicrobial susceptibility phenotype including folate synthesis inhibitors. The marginal ampicillin resistance of DSM30011 most likely derived from chromosomal ADC-type ampC and blaOXA-51-type genes. Searching for catabolic pathways genes revealed several clusters involved in the degradation of plant defenses including woody tissues and a previously unreported atu locus responsible of aliphatic terpenes degradation, thus suggesting that resinous plants may provide an effective niche for this organism. DSM30011 also harbored most genes and regulatory mechanisms linked to persistence and virulence in pathogenic Acinetobacter species. This strain thus revealed important clues into the genomic diversity, virulence potential, and niche ranges of the preantibiotic era A. baumannii population, and may provide an useful tool for our understanding of the processes that led to the recent evolution of this species toward an opportunistic pathogen of humans.
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Affiliation(s)
- Guillermo D. Repizo
- Laboratory of Molecular Microbiology and Structural Biochemistry, CNRS UMR5086, University of Lyon, France
- Departamento de Microbiologia, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Argentina
| | - Alejandro M. Viale
- Departamento de Microbiologia, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Argentina
| | - Vítor Borges
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - María M. Cameranesi
- Departamento de Microbiologia, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Argentina
| | - Najwa Taib
- Laboratoire de Biométrie et Biologie Évolutive, Univ. Lyon, Université Lyon 1, CNRS, UMR5558, Villeurbanne, France
| | - Martín Espariz
- Departamento de Microbiologia, Instituto de Biologia Molecular y Celular de Rosario (IBR, CONICET), Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Argentina
| | - Céline Brochier-Armanet
- Laboratoire de Biométrie et Biologie Évolutive, Univ. Lyon, Université Lyon 1, CNRS, UMR5558, Villeurbanne, France
| | - João Paulo Gomes
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Suzana P. Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, CNRS UMR5086, University of Lyon, France
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43
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Mutations in the β-Subunit of the RNA Polymerase Impair the Surface-Associated Motility and Virulence of Acinetobacter baumannii. Infect Immun 2017; 85:IAI.00327-17. [PMID: 28507065 DOI: 10.1128/iai.00327-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 12/19/2022] Open
Abstract
Acinetobacter baumannii is a major cause of antibiotic-resistant nosocomial infections worldwide. In this study, several rifampin-resistant spontaneous mutants obtained from the A. baumannii ATCC 17978 strain that differed in their point mutations in the rpoB gene, encoding the β-subunit of the RNA polymerase, were isolated. All the mutants harboring amino acid substitutions in position 522 or 540 of the RpoB protein were impaired in surface-associated motility and had attenuated virulence in the fertility model of Caenorhabditis elegans The transcriptional profile of these mutants included six downregulated genes encoding proteins homologous to transporters and metabolic enzymes widespread among A. baumannii clinical isolates. The construction of knockout mutants in each of the six downregulated genes revealed a significant reduction in the surface-associated motility and virulence of four of them in the A. baumannii ATCC 17978 strain, as well as in the virulent clinical isolate MAR002. Taken together, our results provide strong evidence of the connection between motility and virulence in this multiresistant nosocomial pathogen.
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44
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Chen R, Lv R, Xiao L, Wang M, Du Z, Tan Y, Cui Y, Yan Y, Luo Y, Yang R, Song Y. A1S_2811, a CheA/Y-like hybrid two-component regulator from Acinetobacter baumannii ATCC17978, is involved in surface motility and biofilm formation in this bacterium. Microbiologyopen 2017; 6. [PMID: 28714256 PMCID: PMC5635159 DOI: 10.1002/mbo3.510] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/22/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Abstract
Two‐component systems in Acinetobacter baumannii are associated with its virulence, drug resistance, motility, biofilm formation, and other characteristics. In this study, we used RecAb, a genetic engineering method, to investigate the function of A1S_2811 in A. baumannii strain ATCC17978. A1S_2811, a hypothetical hybrid sensor histidine kinase/response regulator, has four histidine‐containing phosphotransfer domains, a CheA‐like regulatory domain, and a CheY‐like receiver domain at its C terminus. Compared with the ATCC17978 strain, both surface motility and biofilm formation at the gas–liquid interface decreased significantly in the A1S_2811 knock‐out strain. The number of pilus‐like structures and the amount of extrapolymeric substances on the cell surface also decreased in the A1S_2811 null strain. Transcription of abaI, which encodes an N‐acylhomoserine lactone synthase in A. baumannii , decreased significantly in the A1S_2811 null strain, and supplementation with synthetic N‐(3‐oxodecanoyl) homoserine‐l‐lactone rescued the surface motility and biofilm formation phenotype in the null mutant. We speculate that A1S_2811 regulates surface motility and biofilm formation, not by regulating type IV pili‐associated genes expression, but by regulating the chaperone/usher pili‐associated csuA/ABCDE operon and the AbaI‐dependent quorum‐sensing pathway‐associated A1S_0112‐0119 operon instead.
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Affiliation(s)
- Rong Chen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.,Department of Clinical Microbiology, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Ruichen Lv
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Lisheng Xiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Min Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zongmin Du
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yafang Tan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yujun Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanping Luo
- Department of Clinical Microbiology, General Hospital of Chinese People's Liberation Army, Beijing, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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An ompR-envZ Two-Component System Ortholog Regulates Phase Variation, Osmotic Tolerance, Motility, and Virulence in Acinetobacter baumannii Strain AB5075. J Bacteriol 2017; 199:JB.00705-16. [PMID: 27872182 DOI: 10.1128/jb.00705-16] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/14/2016] [Indexed: 11/20/2022] Open
Abstract
Recently, a novel phase-variable colony opacity phenotype was discovered in Acinetobacter baumannii strain AB5075, where colonies interconvert between opaque and translucent variants. Opaque colonies become mottled or sectored after 24 h of growth due to translucent variants arising within the colony. This easily distinguishable opaque-colony phenotype was used to screen for random transposon insertions that increased the frequency of sectoring at a time point when wild-type colonies were uniformly opaque. A colony was identified that contained multiple papillae of translucent variants, and the insertion in this mutant mapped to an ortholog of the two-component system response regulator ompR Subsequent investigation of in-frame deletions of ompR and the sensor kinase envZ (located adjacent to ompR) showed that the switching frequency from opaque to translucent was increased 401- and 281-fold, respectively. The ompR mutant also exhibited sensitivity to sodium chloride in growth medium, whereas the envZ mutation did not elicit sensitivity to sodium chloride. Mutation of either gene reduced motility in A. baumannii strain AB5075, but a mutation in both ompR and envZ produced a more profound effect. The ompR and envZ genes were cotranscribed but were not subject to autoregulation by OmpR. Both ompR and envZ mutant opaque variants were attenuated in virulence in the Galleria mellonella infection model, whereas mutation of ompR had no effect on the virulence of the translucent variant. IMPORTANCEAcinetobacter baumannii is a well-known antibiotic-resistant pathogen; many clinical isolates can only be treated by a very small number of antibiotics (including colistin), while some exhibit panresistance. The current antimicrobial arsenal is nearing futility in the treatment of Acinetobacter infections, and new avenues of treatment are profoundly needed. Since phase variation controls the transition between opaque (virulent) and translucent (avirulent) states in A. baumannii, this may represent an "Achilles' heel" that can be targeted via the development of small molecules that lock cells in the translucent state and allow the host immune system to clear the infection. A better understanding of how phase variation is regulated may allow for the development of methods to target this process. The ompR-envZ two-component system ortholog negatively regulates phase variation in A. baumannii, and perturbation of this system leads to the attenuation of virulence in an invertebrate infection model.
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Biosynthesis of polyamines and polyamine-containing molecules. Biochem J 2016; 473:2315-29. [DOI: 10.1042/bcj20160185] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/22/2016] [Indexed: 12/16/2022]
Abstract
Polyamines are evolutionarily ancient polycations derived from amino acids and are pervasive in all domains of life. They are essential for cell growth and proliferation in eukaryotes and are essential, important or dispensable for growth in bacteria. Polyamines present a useful scaffold to attach other moieties to, and are often incorporated into specialized metabolism. Life has evolved multiple pathways to synthesize polyamines, and structural variants of polyamines have evolved in bacteria, archaea and eukaryotes. Among the complex biosynthetic diversity, patterns of evolutionary reiteration can be distinguished, revealing evolutionary recycling of particular protein folds and enzyme chassis. The same enzyme activities have evolved from multiple protein folds, suggesting an inevitability of evolution of polyamine biosynthesis. This review discusses the different biosynthetic strategies used in life to produce diamines, triamines, tetra-amines and branched and long-chain polyamines. It also discusses the enzymes that incorporate polyamines into specialized metabolites and attempts to place polyamine biosynthesis in an evolutionary context.
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Syed Musthafa K, Voravuthikunchai SP. Eugenyl acetate inhibits growth and virulence factors of drug-resistantAcinetobacter baumannii. FLAVOUR FRAG J 2016. [DOI: 10.1002/ffj.3336] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Khadar Syed Musthafa
- Excellent Research Laboratory on Natural Products, Faculty of Science, and Natural Product Research Center of Excellence; Prince of Songkla University; Hat Yai Songkhla Thailand
| | - Supayang Piyawan Voravuthikunchai
- Excellent Research Laboratory on Natural Products, Faculty of Science, and Natural Product Research Center of Excellence; Prince of Songkla University; Hat Yai Songkhla Thailand
- Department of Microbiology, Faculty of Science; Prince of Songkla University; Hat Yai Songkhla Thailand
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Vijayakumar S, Rajenderan S, Laishram S, Anandan S, Balaji V, Biswas I. Biofilm Formation and Motility Depend on the Nature of the Acinetobacter baumannii Clinical Isolates. Front Public Health 2016; 4:105. [PMID: 27252939 PMCID: PMC4877508 DOI: 10.3389/fpubh.2016.00105] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/09/2016] [Indexed: 02/03/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen involved in various infections ranging from minor soft-tissue infections to more severe infections such as ventilator-associated pneumonia and bacteremia. The severity and the type of infections depend on the genetic and phenotypic variations of the strains. In this study, we compared the extent of biofilm formation and motility displayed by 60 multidrug-resistant A. baumannii clinical strains isolated from blood and sputum samples from patients from Southern India. Our results showed that isolates from the sputum samples formed significantly more robust biofilm compared to the blood isolates. On the other hand, we observed that the blood isolates were more motile than the sputum isolates. To the best of our knowledge, this is the first study that systematically evaluated the correlation between these two phenotypic traits and the nature of the isolates.
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Affiliation(s)
- Saranya Vijayakumar
- Department of Clinical Microbiology, Christian Medical College , Vellore , India
| | - Sangeetha Rajenderan
- Department of Clinical Microbiology, Christian Medical College , Vellore , India
| | - Shakti Laishram
- Department of Clinical Microbiology, Christian Medical College , Vellore , India
| | - Shalini Anandan
- Department of Clinical Microbiology, Christian Medical College , Vellore , India
| | - Veeraraghavan Balaji
- Department of Clinical Microbiology, Christian Medical College , Vellore , India
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center , Kansas City, KS , USA
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Characterization of surface antigen protein 1 (SurA1) from Acinetobacter baumannii and its role in virulence and fitness. Vet Microbiol 2016; 186:126-38. [PMID: 27016767 DOI: 10.1016/j.vetmic.2016.02.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 01/24/2016] [Accepted: 02/22/2016] [Indexed: 01/02/2023]
Abstract
Acinetobacter baumannii is a Gram-negative bacillus that causes nosocomial infections, such as bacteremia, pneumonia, and meningitis and urinary tract and wound infections. In the present study, the surface antigen protein 1 (SurA1) gene of A. baumannii strain CCGGD201101 was identified, cloned and expressed, and then its roles in fitness and virulence were investigated. Virulence was observed in the human lung cancer cell lines A549 and HEp-2 at one week after treatment with recombinant SurA1. One isogenic SurA1 knock-out strain, GR0015, which was derived from the A. baumannii strain CCGGD201101 isolated from diseased chicks in a previous study, highlighted the effect of SurA1 on fitness and growth. Its growth rate in LB broth and killing activity in human sera were significantly decreased compared with strain CCGGD201101. In the Galleria mellonella insect model, the isogenic SurA1 knock-out strain exhibited a lower survival rate and decreased dissemination. These results suggest that SurA1 plays an important role in the fitness and virulence of A. baumannii.
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Activity of Norspermidine on Bacterial Biofilms of Multidrug-Resistant Clinical Isolates Associated with Persistent Extremity Wound Infections. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 973:53-70. [PMID: 27864804 DOI: 10.1007/5584_2016_93] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Biofilm formation is a major virulence factor for numerous pathogenic bacteria and is cited as a central event in the pathogenesis of chronic human infections, which is in large part due to excessive extracellular matrix secretion and metabolic changes that occur within the biofilm rendering them highly tolerant to antimicrobial treatments. Polyamines, including norspermidine, play central roles in bacterial biofilm development, but have also recently been shown to inhibit biofilm formation in select strains of various pathogenic bacteria. The aim of this study was to evaluate in vitro the biofilm dispersive and inhibitory activities of norspermidine against multidrug-resistant clinical isolates of Acinetobacter baumannii(n = 4), Klebsiella pneumoniae (n = 3), Pseudomonas aeruginosa (n = 5) and Staphylococcus aureus (n = 4) associated with chronic extremity wound infections using the semi-quantitative 96-well plate method and confocal laser microscopy. In addition to the antibiofilm activity, biocompatibility of norspermidine was also evaluated by measuring toxicity in vitro to human cell lines and whole porcine tissue explants using MTT viability assay and histological analysis. Norspermidine (5-20 mM) had variable dispersive and inhibitory activity on biofilms which was dependent on both the strain and species. Of the clinical bacterial species evaluated herein, A. baumannii isolates were the most sensitive to the effect of norspermidine, which was in part due to the inhibitory effects of norspermidine on bacterial motility and expression of genes involved in the production of homoserine lactones and quorum sensing molecules both essential for biofilm formation. Importantly, exposure of cell lines and whole tissues to norspermidine for prolonged periods of time (≥24 h) was observed to reduce viability and alter tissue histology in a time and concentration dependent manner, with 20 mM exposure having the greatest negative effects on both tissues and individual cell lines. Collectively our findings demonstrate that, similar to other polyamines, norspermidine displays both inhibitory and dispersive activities on biofilms of clinical multidrug-resistant bacterial isolates, in particular for strains of A. baumannii. Additionally our findings suggest that direct application may be considered on tissues, albeit for limited exposure times.
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