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Laborda P, Molin S, Johansen HK, Martínez JL, Hernando-Amado S. Role of bacterial multidrug efflux pumps during infection. World J Microbiol Biotechnol 2024; 40:226. [PMID: 38822187 DOI: 10.1007/s11274-024-04042-7] [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: 04/03/2024] [Accepted: 05/29/2024] [Indexed: 06/02/2024]
Abstract
Multidrug efflux pumps are protein complexes located in the cell envelope that enable bacteria to expel, not only antibiotics, but also a wide array of molecules relevant for infection. Hence, they are important players in microbial pathogenesis. On the one hand, efflux pumps can extrude exogenous compounds, including host-produced antimicrobial molecules. Through this extrusion, pathogens can resist antimicrobial agents and evade host defenses. On the other hand, efflux pumps also have a role in the extrusion of endogenous compounds, such as bacterial intercommunication signaling molecules, virulence factors or metabolites. Therefore, efflux pumps are involved in the modulation of bacterial behavior and virulence, as well as in the maintenance of the bacterial homeostasis under different stresses found within the host. This review delves into the multifaceted roles that efflux pumps have, shedding light on their impact on bacterial virulence and their contribution to bacterial infection. These observations suggest that strategies targeting bacterial efflux pumps could both reinvigorate the efficacy of existing antibiotics and modulate the bacterial pathogenicity to the host. Thus, a comprehensive understanding of bacterial efflux pumps can be pivotal for the development of new effective strategies for the management of infectious diseases.
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Affiliation(s)
- Pablo Laborda
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, 9301, Denmark.
| | - Søren Molin
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Helle Krogh Johansen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, 9301, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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2
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Kumar S, Lekshmi M, Stephen J, Ortiz-Alegria A, Ayitah M, Varela MF. Dynamics of efflux pumps in antimicrobial resistance, persistence, and community living of Vibrionaceae. Arch Microbiol 2023; 206:7. [PMID: 38017151 DOI: 10.1007/s00203-023-03731-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/30/2023]
Abstract
The marine bacteria of the Vibrionaceae family are significant from the point of view of their role in the marine geochemical cycle, as well as symbionts and opportunistic pathogens of aquatic animals and humans. The well-known pathogens of this group, Vibrio cholerae, V. parahaemolyticus, and V. vulnificus, are responsible for significant morbidity and mortality associated with a range of infections from gastroenteritis to bacteremia acquired through the consumption of raw or undercooked seafood and exposure to seawater containing these pathogens. Although generally regarded as susceptible to commonly employed antibiotics, the antimicrobial resistance of Vibrio spp. has been on the rise in the last two decades, which has raised concern about future infections by these bacteria becoming increasingly challenging to treat. Diverse mechanisms of antimicrobial resistance have been discovered in pathogenic vibrios, the most important being the membrane efflux pumps, which contribute to antimicrobial resistance and their virulence, environmental fitness, and persistence through biofilm formation and quorum sensing. In this review, we discuss the evolution of antimicrobial resistance in pathogenic vibrios and some of the well-characterized efflux pumps' contributions to the physiology of antimicrobial resistance, host and environment survival, and their pathogenicity.
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Affiliation(s)
- Sanath Kumar
- QC Laboratory, Post-Harvest Technology, ICAR-Central Institute of Fisheries Education (CIFE), Mumbai, 400061, India
| | - Manjusha Lekshmi
- QC Laboratory, Post-Harvest Technology, ICAR-Central Institute of Fisheries Education (CIFE), Mumbai, 400061, India
| | - Jerusha Stephen
- QC Laboratory, Post-Harvest Technology, ICAR-Central Institute of Fisheries Education (CIFE), Mumbai, 400061, India
| | - Anely Ortiz-Alegria
- Department of Biology, Eastern New Mexico University, Station 33, Portales, NM, 88130, USA
| | - Matthew Ayitah
- Department of Biology, Eastern New Mexico University, Station 33, Portales, NM, 88130, USA
| | - Manuel F Varela
- Department of Biology, Eastern New Mexico University, Station 33, Portales, NM, 88130, USA.
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3
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Bina XR, Bina JE. Vibrio cholerae RND efflux systems: mediators of stress responses, colonization and pathogenesis. Front Cell Infect Microbiol 2023; 13:1203487. [PMID: 37256112 PMCID: PMC10225521 DOI: 10.3389/fcimb.2023.1203487] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 04/25/2023] [Indexed: 06/01/2023] Open
Abstract
Resistance Nodulation Division (RND) efflux systems are ubiquitous transporters in gram-negative bacteria that provide protection against antimicrobial agents and thereby enhance survival in virtually all environments these prokaryotes inhabit. Vibrio cholerae is a dual lifestyle enteric pathogen that spends much of its existence in aquatic environments. An unwitting encounter with a human host can lead to V. cholerae intestinal colonization by strains that encode cholera toxin and toxin co-regulated pilus virulence factors leading to potentially fatal cholera diarrhea and dissemination in the environment. Adaptive response mechanisms to host factors encountered by these pathogens are therefore critical both to engage survival mechanisms such as RND-mediated transporters and to induce timely expression of virulence factors. Sensing of cues encountered in the host may therefore activate more than protective responses such as efflux systems, but also be coordinated to initiate expression of virulence factors. This review summarizes recent advances that contribute towards the understanding of RND efflux physiological functions and how the transport systems interface with the regulation of virulence factor production in V. cholerae.
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Affiliation(s)
| | - James E. Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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4
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Creasy-Marrazzo A, Saber MM, Kamat M, Bailey LS, Brinkley L, Cato E, Begum Y, Rashid MM, Khan AI, Qadri F, Basso KB, Shapiro BJ, Nelson EJ. Genome-wide association studies reveal distinct genetic correlates and increased heritability of antimicrobial resistance in Vibrio cholerae under anaerobic conditions. Microb Genom 2022; 8:mgen000905. [PMID: 36748512 PMCID: PMC9837564 DOI: 10.1099/mgen.0.000905] [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] [Indexed: 12/07/2022] Open
Abstract
The antibiotic formulary is threatened by high rates of antimicrobial resistance (AMR) among enteropathogens. Enteric bacteria are exposed to anaerobic conditions within the gastrointestinal tract, yet little is known about how oxygen exposure influences AMR. The facultative anaerobe Vibrio cholerae was chosen as a model to address this knowledge gap. We obtained V. cholerae isolates from 66 cholera patients, sequenced their genomes, and grew them under anaerobic and aerobic conditions with and without three clinically relevant antibiotics (ciprofloxacin, azithromycin, doxycycline). For ciprofloxacin and azithromycin, the minimum inhibitory concentration (MIC) increased under anaerobic conditions compared to aerobic conditions. Using standard resistance breakpoints, the odds of classifying isolates as resistant increased over 10 times for ciprofloxacin and 100 times for azithromycin under anaerobic conditions compared to aerobic conditions. For doxycycline, nearly all isolates were sensitive under both conditions. Using genome-wide association studies, we found associations between genetic elements and AMR phenotypes that varied by oxygen exposure and antibiotic concentrations. These AMR phenotypes were more heritable, and the AMR-associated genetic elements were more often discovered, under anaerobic conditions. These AMR-associated genetic elements are promising targets for future mechanistic research. Our findings provide a rationale to determine whether increased MICs under anaerobic conditions are associated with therapeutic failures and/or microbial escape in cholera patients. If so, there may be a need to determine new AMR breakpoints for anaerobic conditions.
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Affiliation(s)
- Ashton Creasy-Marrazzo
- Departments of Pediatrics, University of Florida, Gainesville, FL, USA,Department of Environmental and Global Health, University of Florida, Gainesville, FL, USA
| | - Morteza M. Saber
- Department of Microbiology and Immunology, McGill University, Gainesville, FL, USA
| | - Manasi Kamat
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Laura S. Bailey
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Lindsey Brinkley
- Departments of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Emilee Cato
- Departments of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Yasmin Begum
- Infectious Diseases Division (IDD) and Nutrition and Clinical Services Division (NCSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), Dhaka, Bangladesh
| | - Md. Mahbubur Rashid
- Infectious Diseases Division (IDD) and Nutrition and Clinical Services Division (NCSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), Dhaka, Bangladesh
| | - Ashraful I. Khan
- Infectious Diseases Division (IDD) and Nutrition and Clinical Services Division (NCSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), Dhaka, Bangladesh
| | - Firdausi Qadri
- Infectious Diseases Division (IDD) and Nutrition and Clinical Services Division (NCSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), Dhaka, Bangladesh
| | - Kari B. Basso
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - B. Jesse Shapiro
- Department of Microbiology and Immunology, McGill University, Gainesville, FL, USA,*Correspondence: B. Jesse Shapiro,
| | - Eric J. Nelson
- Departments of Pediatrics, University of Florida, Gainesville, FL, USA,*Correspondence: Eric J. Nelson,
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5
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Stephen J, Lekshmi M, Ammini P, Kumar SH, Varela MF. Membrane Efflux Pumps of Pathogenic Vibrio Species: Role in Antimicrobial Resistance and Virulence. Microorganisms 2022; 10:microorganisms10020382. [PMID: 35208837 PMCID: PMC8875612 DOI: 10.3390/microorganisms10020382] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/15/2022] [Accepted: 01/23/2022] [Indexed: 02/06/2023] Open
Abstract
Infectious diseases caused by bacterial species of the Vibrio genus have had considerable significance upon human health for centuries. V. cholerae is the causative microbial agent of cholera, a severe ailment characterized by profuse watery diarrhea, a condition associated with epidemics, and seven great historical pandemics. V. parahaemolyticus causes wound infection and watery diarrhea, while V. vulnificus can cause wound infections and septicemia. Species of the Vibrio genus with resistance to multiple antimicrobials have been a significant health concern for several decades. Mechanisms of antimicrobial resistance machinery in Vibrio spp. include biofilm formation, drug inactivation, target protection, antimicrobial permeability reduction, and active antimicrobial efflux. Integral membrane-bound active antimicrobial efflux pump systems include primary and secondary transporters, members of which belong to closely related protein superfamilies. The RND (resistance-nodulation-division) pumps, the MFS (major facilitator superfamily) transporters, and the ABC superfamily of efflux pumps constitute significant drug transporters for investigation. In this review, we explore these antimicrobial transport systems in the context of Vibrio spp. pathogenesis and virulence.
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Affiliation(s)
- Jerusha Stephen
- QC Laboratory, Harvest and Post-Harvest Technology Division, Central Institute of Fisheries Education (CIFE), Seven Bungalows, Versova, Andheri (W), Mumbai 400061, India; (J.S.); (M.L.); (S.H.K.)
| | - Manjusha Lekshmi
- QC Laboratory, Harvest and Post-Harvest Technology Division, Central Institute of Fisheries Education (CIFE), Seven Bungalows, Versova, Andheri (W), Mumbai 400061, India; (J.S.); (M.L.); (S.H.K.)
| | - Parvathi Ammini
- Department of Biotechnology, Cochin University of Science and Technology, Kochi 682022, India;
| | - Sanath H. Kumar
- QC Laboratory, Harvest and Post-Harvest Technology Division, Central Institute of Fisheries Education (CIFE), Seven Bungalows, Versova, Andheri (W), Mumbai 400061, India; (J.S.); (M.L.); (S.H.K.)
| | - Manuel F. Varela
- Department of Biology, Eastern New Mexico University, Portales, NM 88130, USA
- Correspondence:
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6
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Shome S, Sankar K, Jernigan RL. Simulated Drug Efflux for the AbgT Family of Membrane Transporters. J Chem Inf Model 2021; 61:5673-5681. [PMID: 34714659 DOI: 10.1021/acs.jcim.1c00516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drug extrusion through molecular efflux pumps is an important mechanism for the survival of many pathogenic bacteria by removing drugs, providing multidrug resistance (MDR). Understanding molecular mechanisms for drug extrusion in multidrug efflux pumps is important for the development of new antiresistance drugs. The AbgT family of transporters involved in the folic acid biosynthesis pathway represents one such important efflux pump system. In addition to the transport of the folic acid precursor p-amino benzoic acid (PABA), members of this family are involved in the efflux of several sulfa drugs, conferring drug resistance to the bacteria. With the availability of structures for two members of this family (YdaH and MtrF), we investigate molecular pathways for transport of PABA and a sulfa drug (sulfamethazine) particularly for the YdaH transporter using steered molecular dynamics. Our analyses reveal the probable ligand migration pathways through the transporter, which also identifies key residues along the transport pathway. In addition, simulations using both PABA and sulfamethazine show how the protein is able to transport ligands of different shapes and sizes out of the pathogen. Our observations confirm previously reported functional residues for transport along the pathways by which YdaH transporters achieve antibiotic resistance to shuttle drugs out of the cells.
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Affiliation(s)
- Sayane Shome
- Bioinformatics and Computational Biology Program Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Kannan Sankar
- Bioinformatics and Computational Biology Program Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Robert L Jernigan
- Bioinformatics and Computational Biology Program Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
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7
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Lo CC, Liao WY, Chou MC, Wu YY, Yeh TH, Lo HR. Overexpression of Resistance-Nodulation-Division Efflux Pump Genes Contributes to Multidrug Resistance in Aeromonas hydrophila Clinical Isolates. Microb Drug Resist 2021; 28:153-160. [PMID: 34609911 DOI: 10.1089/mdr.2021.0084] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aeromonas hydrophila is a Gram-negative bacterium that is a critical causative agent of infections in fish and is occasionally responsible for human infections following contact with contaminated water or food. Currently, the extensive use of antibiotics in clinical practice has led to increased number of isolates of multidrug-resistant (MDR) Aeromonas and has posed a serious public health challenge. The efflux pump system is a critical mechanism of antibiotic resistance in most Gram-negative bacteria. However, the role of resistance-nodulation-division (RND)-type efflux pumps in MDR A. hydrophila is not fully understood. We aimed to evaluate the contribution of the RND efflux pump system to MDR A. hydrophila clinical isolates. PCR results indicated a considerable variation in the presence of RND efflux pump genes in clinical isolates compared to that of the environmental reference strain ATCC7966T. Compared to non-MDR clinical isolates, the expression levels of three putative RND efflux pump genes, AHA0021, AHA1320, and AheB, were significantly elevated in MDR strains. The minimal inhibitory concentrations of piperacillin/tazobactam, imipenem, erythromycin, and polymyxin B were significantly reduced by phenylalanine-arginine β-naphthylamide (PAβN), further supporting the contribution of the RND efflux system in MDR A. hydrophila. We provided evidence supporting the contribution of the RND efflux system to multidrug resistance in A. hydrophila clinical isolates. Further studies are warranted to elucidate the detailed mechanisms that confer intrinsic resistance to antimicrobials in A. hydrophila.
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Affiliation(s)
- Chung-Cheng Lo
- Department of Internal Medicine, Kaohsiung Veterans General Hospital Pingtung Branch, Pingtung, Taiwan
| | - Wan-Yu Liao
- Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung, Taiwan
| | - Miao-Chen Chou
- Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung, Taiwan
| | - Yu-Yi Wu
- Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung, Taiwan
| | - Tzu-Hui Yeh
- Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital Pingtung Branch, Pingtung, Taiwan
| | - Horng-Ren Lo
- Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung, Taiwan
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8
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De R. Mobile Genetic Elements of Vibrio cholerae and the Evolution of Its Antimicrobial Resistance. FRONTIERS IN TROPICAL DISEASES 2021. [DOI: 10.3389/fitd.2021.691604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Vibrio cholerae (VC) is the causative agent of the severe dehydrating diarrheal disease cholera. The primary treatment for cholera is oral rehydration therapy (ORT). However, in case of moderate to severe dehydration, antibiotics are administered to reduce morbidity. Due to the emergence of multidrug resistant (MDR) strains of VC routinely used antibiotics fail to be effective in cholera patients. Antimicrobial resistance (AMR) is encoded in the genome of bacteria and is usually acquired from other organisms cohabiting in the environment or in the gut with which it interacts in the gut or environmental niche. The antimicrobial resistance genes (ARGs) are usually borne on mobile genetic elements (MGEs) like plasmids, transposons, integrons and SXT constin. Horizontal gene transfer (HGT) helps in the exchange of ARGs among bacteria leading to dissemination of AMR. In VC the acquisition and loss of AMR to many antibiotics have been found to be a dynamic process. This review describes the different AMR determinants and mechanisms of resistance that have been discovered in VC. These ARGs borne usually on MGEs have been recovered from isolates associated with past and present epidemics worldwide. These are responsible for resistance of VC to common antibiotics and are periodically lost and gained contributing to its genetic evolution. These resistance markers can be routinely used for AMR surveillance in VC. The review also presents a precise perspective on the importance of the gut microbiome in the emergence of MDR VC and concludes that the gut microbiome is a potential source of molecular markers and networks which can be manipulated for the interception of AMR in the future.
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9
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Alav I, Kobylka J, Kuth MS, Pos KM, Picard M, Blair JMA, Bavro VN. Structure, Assembly, and Function of Tripartite Efflux and Type 1 Secretion Systems in Gram-Negative Bacteria. Chem Rev 2021; 121:5479-5596. [PMID: 33909410 PMCID: PMC8277102 DOI: 10.1021/acs.chemrev.1c00055] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Tripartite efflux pumps and the related type 1 secretion systems (T1SSs) in Gram-negative organisms are diverse in function, energization, and structural organization. They form continuous conduits spanning both the inner and the outer membrane and are composed of three principal components-the energized inner membrane transporters (belonging to ABC, RND, and MFS families), the outer membrane factor channel-like proteins, and linking the two, the periplasmic adaptor proteins (PAPs), also known as the membrane fusion proteins (MFPs). In this review we summarize the recent advances in understanding of structural biology, function, and regulation of these systems, highlighting the previously undescribed role of PAPs in providing a common architectural scaffold across diverse families of transporters. Despite being built from a limited number of basic structural domains, these complexes present a staggering variety of architectures. While key insights have been derived from the RND transporter systems, a closer inspection of the operation and structural organization of different tripartite systems reveals unexpected analogies between them, including those formed around MFS- and ATP-driven transporters, suggesting that they operate around basic common principles. Based on that we are proposing a new integrated model of PAP-mediated communication within the conformational cycling of tripartite systems, which could be expanded to other types of assemblies.
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Affiliation(s)
- Ilyas Alav
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Jessica Kobylka
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Miriam S. Kuth
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Klaas M. Pos
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Martin Picard
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS
UMR 7099, Université de Paris, 75005 Paris, France
- Fondation
Edmond de Rothschild pour le développement de la recherche
Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Jessica M. A. Blair
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Vassiliy N. Bavro
- School
of Life Sciences, University of Essex, Colchester, CO4 3SQ United Kingdom
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10
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Ramamurthy T, Nandy RK, Mukhopadhyay AK, Dutta S, Mutreja A, Okamoto K, Miyoshi SI, Nair GB, Ghosh A. Virulence Regulation and Innate Host Response in the Pathogenicity of Vibrio cholerae. Front Cell Infect Microbiol 2020; 10:572096. [PMID: 33102256 PMCID: PMC7554612 DOI: 10.3389/fcimb.2020.572096] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
The human pathogen Vibrio cholerae is the causative agent of severe diarrheal disease known as cholera. Of the more than 200 "O" serogroups of this pathogen, O1 and O139 cause cholera outbreaks and epidemics. The rest of the serogroups, collectively known as non-O1/non-O139 cause sporadic moderate or mild diarrhea and also systemic infections. Pathogenic V. cholerae circulates between nutrient-rich human gut and nutrient-deprived aquatic environment. As an autochthonous bacterium in the environment and as a human pathogen, V. cholerae maintains its survival and proliferation in these two niches. Growth in the gastrointestinal tract involves expression of several genes that provide bacterial resistance against host factors. An intricate regulatory program involving extracellular signaling inputs is also controlling this function. On the other hand, the ability to store carbon as glycogen facilitates bacterial fitness in the aquatic environment. To initiate the infection, V. cholerae must colonize the small intestine after successfully passing through the acid barrier in the stomach and survive in the presence of bile and antimicrobial peptides in the intestinal lumen and mucus, respectively. In V. cholerae, virulence is a multilocus phenomenon with a large functionally associated network. More than 200 proteins have been identified that are functionally linked to the virulence-associated genes of the pathogen. Several of these genes have a role to play in virulence and/or in functions that have importance in the human host or the environment. A total of 524 genes are differentially expressed in classical and El Tor strains, the two biotypes of V. cholerae serogroup O1. Within the host, many immune and biological factors are able to induce genes that are responsible for survival, colonization, and virulence. The innate host immune response to V. cholerae infection includes activation of several immune protein complexes, receptor-mediated signaling pathways, and other bactericidal proteins. This article presents an overview of regulation of important virulence factors in V. cholerae and host response in the context of pathogenesis.
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Affiliation(s)
| | - Ranjan K Nandy
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Asish K Mukhopadhyay
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shanta Dutta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Ankur Mutreja
- Global Health-Infectious Diseases, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Keinosuke Okamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.,Collaborative Research Center of Okayama University for Infectious Diseases in India, National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shin-Ichi Miyoshi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - G Balakrish Nair
- Microbiome Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Amit Ghosh
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases, Kolkata, India
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11
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The Great ESKAPE: Exploring the Crossroads of Bile and Antibiotic Resistance in Bacterial Pathogens. Infect Immun 2020; 88:IAI.00865-19. [PMID: 32661122 DOI: 10.1128/iai.00865-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Throughout the course of infection, many pathogens encounter bactericidal conditions that threaten the viability of the bacteria and impede the establishment of infection. Bile is one of the most innately bactericidal compounds present in humans, functioning to reduce the bacterial burden in the gastrointestinal tract while also aiding in digestion. It is becoming increasingly apparent that pathogens successfully resist the bactericidal conditions of bile, including bacteria that do not normally cause gastrointestinal infections. This review highlights the ability of Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter (ESKAPE), and other enteric pathogens to resist bile and how these interactions can impact the sensitivity of bacteria to various antimicrobial agents. Given that pathogen exposure to bile is an essential component to gastrointestinal transit that cannot be avoided, understanding how bile resistance mechanisms align with antimicrobial resistance is vital to our ability to develop new, successful therapeutics in an age of widespread and increasing antimicrobial resistance.
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12
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13
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Vibrio cholerae OmpR Represses the ToxR Regulon in Response to Membrane Intercalating Agents That Are Prevalent in the Human Gastrointestinal Tract. Infect Immun 2020; 88:IAI.00912-19. [PMID: 31871096 DOI: 10.1128/iai.00912-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 12/17/2019] [Indexed: 12/20/2022] Open
Abstract
Multidrug efflux systems belonging to the resistance-nodulation-division (RND) superfamily are ubiquitous in Gram-negative bacteria. RND efflux systems are often associated with multiple antimicrobial resistance and also contribute to the expression of diverse bacterial phenotypes including virulence, as documented in the intestinal pathogen Vibrio cholerae, the causative agent of the severe diarrheal disease cholera. Transcriptomic studies with RND efflux-negative V. cholerae suggested that RND-mediated efflux was required for homeostasis, as loss of RND efflux resulted in the activation of transcriptional regulators, including multiple environmental sensing systems. In this report, we investigated six RND efflux-responsive regulatory genes for contributions to V. cholerae virulence factor production. Our data showed that the V. cholerae gene VC2714, encoding a homolog of Escherichia coli OmpR, was a virulence repressor. The expression of ompR was elevated in an RND-null mutant, and ompR deletion partially restored virulence factor production in the RND-negative background. Virulence inhibitory activity in the RND-negative background resulted from OmpR repression of the key ToxR regulon virulence activator aphB, and ompR overexpression in wild-type cells also repressed virulence through aphB We further show that ompR expression was not altered by changes in osmolarity but instead was induced by membrane-intercalating agents that are prevalent in the host gastrointestinal tract and which are substrates of the V. cholerae RND efflux systems. Our collective results indicate that V. cholerae ompR is an aphB repressor and regulates the expression of the ToxR virulence regulon in response to novel environmental cues.
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14
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Colclough AL, Alav I, Whittle EE, Pugh HL, Darby EM, Legood SW, McNeil HE, Blair JM. RND efflux pumps in Gram-negative bacteria; regulation, structure and role in antibiotic resistance. Future Microbiol 2020; 15:143-157. [PMID: 32073314 DOI: 10.2217/fmb-2019-0235] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Rresistance-nodulation-division (RND) efflux pumps in Gram-negative bacteria remove multiple, structurally distinct classes of antimicrobials from inside bacterial cells therefore directly contributing to multidrug resistance. There is also emerging evidence that many other mechanisms of antibiotic resistance rely on the intrinsic resistance conferred by RND efflux. In addition to their role in antibiotic resistance, new information has become available about the natural role of RND pumps including their established role in virulence of many Gram-negative organisms. This review also discusses the recent advances in understanding the regulation and structure of RND efflux pumps.
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Affiliation(s)
- Abigail L Colclough
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Ilyas Alav
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Emily E Whittle
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Hannah L Pugh
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Elizabeth M Darby
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Simon W Legood
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Helen E McNeil
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Jessica Ma Blair
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Lloyd NA, Nazaret S, Barkay T. Genome-facilitated discovery of RND efflux pump-mediated resistance to cephalosporins in Vibrio spp. isolated from the mummichog fish gut. J Glob Antimicrob Resist 2019; 19:294-300. [DOI: 10.1016/j.jgar.2019.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 05/06/2019] [Indexed: 01/22/2023] Open
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Hews CL, Cho T, Rowley G, Raivio TL. Maintaining Integrity Under Stress: Envelope Stress Response Regulation of Pathogenesis in Gram-Negative Bacteria. Front Cell Infect Microbiol 2019; 9:313. [PMID: 31552196 PMCID: PMC6737893 DOI: 10.3389/fcimb.2019.00313] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
The Gram-negative bacterial envelope is an essential interface between the intracellular and harsh extracellular environment. Envelope stress responses (ESRs) are crucial to the maintenance of this barrier and function to detect and respond to perturbations in the envelope, caused by environmental stresses. Pathogenic bacteria are exposed to an array of challenging and stressful conditions during their lifecycle and, in particular, during infection of a host. As such, maintenance of envelope homeostasis is essential to their ability to successfully cause infection. This review will discuss our current understanding of the σE- and Cpx-regulated ESRs, with a specific focus on their role in the virulence of a number of model pathogens.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Timothy Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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Pasqua M, Grossi M, Scinicariello S, Aussel L, Barras F, Colonna B, Prosseda G. The MFS efflux pump EmrKY contributes to the survival of Shigella within macrophages. Sci Rep 2019; 9:2906. [PMID: 30814604 PMCID: PMC6393483 DOI: 10.1038/s41598-019-39749-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 01/29/2019] [Indexed: 02/04/2023] Open
Abstract
Efflux pumps are membrane protein complexes conserved in all living organisms. Beyond being involved in antibiotic extrusion in several bacteria, efflux pumps are emerging as relevant players in pathogen-host interactions. We have investigated on the possible role of the efflux pump network in Shigella flexneri, the etiological agent of bacillary dysentery. We have found that S. flexneri has retained 14 of the 20 pumps characterized in Escherichia coli and that their expression is differentially modulated during the intracellular life of Shigella. In particular, the emrKY operon, encoding an efflux pump of the Major Facilitator Superfamily, is specifically and highly induced in Shigella-infected U937 macrophage-like cells and is activated in response to a combination of high K+ and acidic pH, which are sensed by the EvgS/EvgA two-component system. Notably, we show that following S. flexneri infection, macrophage cytosol undergoes a mild reduction of intracellular pH, permitting EvgA to trigger the emrKY activation. Finally, we present data suggesting that EmrKY is required for the survival of Shigella in the harsh macrophage environment, highlighting for the first time the key role of an efflux pump during the Shigella invasive process.
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Affiliation(s)
- Martina Pasqua
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Milena Grossi
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Sara Scinicariello
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Laurent Aussel
- Aix-Marseille Univ, CNRS, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Marseille, France
| | | | - Bianca Colonna
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Gianni Prosseda
- Istituto Pasteur Italia, Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy.
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Blanco P, Sanz-García F, Hernando-Amado S, Martínez JL, Alcalde-Rico M. The development of efflux pump inhibitors to treat Gram-negative infections. Expert Opin Drug Discov 2018; 13:919-931. [PMID: 30198793 DOI: 10.1080/17460441.2018.1514386] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION One of the possibilities for reducing the emergence and spread of antibiotic resistance is the use of anti-resistance compounds capable of resensitizing resistant microorganisms to current antimicrobials. For this purpose, multidrug efflux pumps, whose inhibition may increase bacterial susceptibility to several antibiotics, including macrolides to which Gram-negatives are considered intrinsically resistant, have emerged as suitable targets. Areas covered: In the current review, the authors discuss different mechanisms that can be exploited for inhibiting multidrug efflux pumps and describe the properties and the potential therapeutic value of already studied efflux pumps inhibitors. Although efforts have already been made to develop these inhibitors, there are currently no good candidates for treating infectious diseases. Consequently, the authors also discuss potential approaches for their development. Expert opinion: Classical anti-resistance drugs such as beta-lactamases inhibitors, while useful, are only purposeful for treating infections caused by beta-lactamase producers. However, inhibitors of multidrug efflux pumps, which are present on all organisms, can sensitize both susceptible and resistant bacteria to antibiotics belonging to several different structural families. Since some efflux pumps are involved in bacterial infections, their inhibition may also reduce the infectivity of Gram-negative bacterial pathogens.
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Affiliation(s)
- Paula Blanco
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Fernando Sanz-García
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Sara Hernando-Amado
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - José Luis Martínez
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Manuel Alcalde-Rico
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
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Bina XR, Howard MF, Taylor-Mulneix DL, Ante VM, Kunkle DE, Bina JE. The Vibrio cholerae RND efflux systems impact virulence factor production and adaptive responses via periplasmic sensor proteins. PLoS Pathog 2018; 14:e1006804. [PMID: 29304169 PMCID: PMC5773229 DOI: 10.1371/journal.ppat.1006804] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 01/18/2018] [Accepted: 12/11/2017] [Indexed: 12/18/2022] Open
Abstract
Resistance-nodulation-division (RND) efflux systems are ubiquitous transporters in Gram-negative bacteria that are essential for antibiotic resistance. The RND efflux systems also contribute to diverse phenotypes independent of antimicrobial resistance, but the mechanism by which they affect most of these phenotypes is unclear. This is the case in Vibrio cholerae where the RND systems function in antimicrobial resistance and virulence factor production. Herein, we investigated the linkage between RND efflux and V. cholerae virulence. RNA sequencing revealed that the loss of RND efflux affected the activation state of periplasmic sensing systems including the virulence regulator ToxR. Activation of ToxR in an RND null mutant resulted in ToxR-dependent transcription of the LysR-family regulator leuO. Increased leuO transcription resulted in the repression of the ToxR virulence regulon and attenuated virulence factor production. Consistent with this, leuO deletion restored virulence factor production in an RND-null mutant, but not its ability to colonize infant mice; suggesting that RND efflux was epistatic to virulence factor production for colonization. The periplasmic sensing domain of ToxR was required for the induction of leuO transcription in the RND null mutant, suggesting that ToxR responded to metabolites that accumulated in the periplasm. Our results suggest that ToxR represses virulence factor production in response to metabolites that are normally effluxed from the cell by the RND transporters. We propose that impaired RND efflux results in periplasmic metabolite accumulation, which then activates periplasmic sensors including ToxR and two-component regulatory systems to initiate the expression of adaptive responses.
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Affiliation(s)
- X. Renee Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Mondraya F. Howard
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Dawn L. Taylor-Mulneix
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Vanessa M. Ante
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Dillon E. Kunkle
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - James E. Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
- * E-mail:
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20
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Lo CC, Lin PT, Chiang-Ni C, Lin KH, Lee SL, Kuo TF, Lo HR. Contribution of efflux systems to the detergent resistance, cytotoxicity, and biofilm formation of Vibrio vulnificus. GENE REPORTS 2017. [DOI: 10.1016/j.genrep.2017.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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The Vibrio cholerae var regulon encodes a metallo-β-lactamase and an antibiotic efflux pump, which are regulated by VarR, a LysR-type transcription factor. PLoS One 2017; 12:e0184255. [PMID: 28898293 PMCID: PMC5595328 DOI: 10.1371/journal.pone.0184255] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022] Open
Abstract
The genome sequence of V. cholerae O1 Biovar Eltor strain N16961 has revealed a putative antibiotic resistance (var) regulon that is predicted to encode a transcriptional activator (VarR), which is divergently transcribed relative to the putative resistance genes for both a metallo-β-lactamase (VarG) and an antibiotic efflux-pump (VarABCDEF). We sought to test whether these genes could confer antibiotic resistance and are organised as a regulon under the control of VarR. VarG was overexpressed and purified and shown to have β-lactamase activity against penicillins, cephalosporins and carbapenems, having the highest activity against meropenem. The expression of VarABCDEF in the Escherichia coli (ΔacrAB) strain KAM3 conferred resistance to a range of drugs, but most significant resistance was to the macrolide spiramycin. A gel-shift analysis was used to determine if VarR bound to the promoter regions of the resistance genes. Consistent with the regulation of these resistance genes, VarR binds to three distinct intergenic regions, varRG, varGA and varBC located upstream and adjacent to varG, varA and varC, respectively. VarR can act as a repressor at the varRG promoter region; whilst this repression was relieved upon addition of β-lactams, these did not dissociate the VarR/varRG-DNA complex, indicating that the de-repression of varR by β-lactams is indirect. Considering that the genomic arrangement of VarR-VarG is strikingly similar to that of AmpR-AmpC system, it is possible that V. cholerae has evolved a system for resistance to the newer β-lactams that would prove more beneficial to the bacterium in light of current selective pressures.
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The Vibrio cholerae VexGH RND Efflux System Maintains Cellular Homeostasis by Effluxing Vibriobactin. mBio 2017; 8:mBio.00126-17. [PMID: 28512090 PMCID: PMC5433094 DOI: 10.1128/mbio.00126-17] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Resistance-nodulation-division (RND) superfamily efflux systems have been widely studied for their role in antibiotic resistance, but their native biological functions remain poorly understood. We previously showed that loss of RND-mediated efflux in Vibrio cholerae resulted in activation of the Cpx two-component regulatory system, which mediates adaptation to stress resulting from misfolded membrane proteins. Here, we investigated the mechanism linking RND-mediated efflux to the Cpx response. We performed transposon mutagenesis screening of RND-deficient V. cholerae to identify Cpx suppressors. Suppressor mutations mapped to genes involved in the biosynthesis of the catechol siderophore vibriobactin. We subsequently demonstrated that vibriobactin secretion is impaired in mutants lacking the VexGH RND efflux system and that impaired vibriobactin secretion is responsible for Cpx system activation, suggesting that VexGH secretes vibriobactin. This conclusion was bolstered by results showing that vexGH expression is induced by iron limitation and that vexH-deficient cells exhibit reduced fitness during growth under iron-limiting conditions. Our results support a model where VexGH contributes to cellular homeostasis by effluxing vibriobactin. In the absence of vexGH, retained vibriobactin appears to chelate iron from iron-rich components of the respiratory chain, with the deferrated proteins functioning to activate the Cpx response. Our collective results demonstrate that a native function of the V. cholerae VexGH RND efflux system is in vibriobactin secretion and that vibriobactin efflux is critical for maintenance of cellular homeostasis.IMPORTANCE RND efflux systems are ubiquitous Gram-negative transporters that play critical roles in antimicrobial resistance. In addition to antimicrobial resistance, RND transporters also affect the expression of diverse phenotypes, including virulence, cell metabolism, and stress responses. The latter observations suggest that RND transporters fulfill unknown physiological functions in the cell independently of their role in antimicrobial resistance. Vibrio cholerae is representative of many Gram-negative bacteria in encoding multiple RND transporters that are redundant in antimicrobial resistance and affect multiple phenotypes. Here we describe a novel function of the V. cholerae VexGH RND transporter in vibriobactin secretion. We show that vibriobactin production in VexGH-deficient cells impacts cell homeostasis, leading to activation of the Cpx stress response and reduced fitness under iron-limiting conditions. Our results highlight a native physiological function of an RND transporter and provide insight into the selective forces that maintain what was thought to be a redundant multidrug transporter.
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Spengler G, Kincses A, Gajdács M, Amaral L. New Roads Leading to Old Destinations: Efflux Pumps as Targets to Reverse Multidrug Resistance in Bacteria. Molecules 2017; 22:molecules22030468. [PMID: 28294992 PMCID: PMC6155429 DOI: 10.3390/molecules22030468] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023] Open
Abstract
Multidrug resistance (MDR) has appeared in response to selective pressures resulting from the incorrect use of antibiotics and other antimicrobials. This inappropriate application and mismanagement of antibiotics have led to serious problems in the therapy of infectious diseases. Bacteria can develop resistance by various mechanisms and one of the most important factors resulting in MDR is efflux pump-mediated resistance. Because of the importance of the efflux-related multidrug resistance the development of new therapeutic approaches aiming to inhibit bacterial efflux pumps is a promising way to combat bacteria having over-expressed MDR efflux systems. The definition of an efflux pump inhibitor (EPI) includes the ability to render the bacterium increasingly more sensitive to a given antibiotic or even reverse the multidrug resistant phenotype. In the recent years numerous EPIs have been developed, although so far their clinical application has not yet been achieved due to their in vivo toxicity and side effects. In this review, we aim to give a short overview of efflux mediated resistance in bacteria, EPI compounds of plant and synthetic origin, and the possible methods to investigate and screen EPI compounds in bacterial systems.
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Affiliation(s)
- Gabriella Spengler
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Annamária Kincses
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Márió Gajdács
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Leonard Amaral
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
- Travel Medicine, Institute of Hygiene and Tropical Medicine, Universidade Nova de Lisboa, 1349-008 Lisbon, Portugal.
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Oladokun MO, Okoh IA. Vibrio cholerae: A historical perspective and current trend. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2016. [DOI: 10.1016/s2222-1808(16)61154-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bina XR, Howard MF, Ante VM, Bina JE. Vibrio cholerae LeuO Links the ToxR Regulon to Expression of Lipid A Remodeling Genes. Infect Immun 2016; 84:3161-3171. [PMID: 27550934 PMCID: PMC5067749 DOI: 10.1128/iai.00445-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/14/2016] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae is an intestinal pathogen that causes the diarrheal disease cholera. Colonization of the intestine depends upon the expression of genes that allow V. cholerae to overcome host barriers, including low pH, bile acids, and the innate immune system. ToxR is a major contributor to this process. ToxR is a membrane-spanning transcription factor that coordinates gene expression in response to environmental cues. In previous work we showed that ToxR upregulated leuO expression in response to bile salts. LeuO is a LysR family transcription factor that contributes to acid tolerance, bile resistance, and biofilm formation in V. cholerae Here, we investigated the function of ToxR and LeuO in cationic antimicrobial peptide (CAMP) resistance. We report that ToxR and LeuO contribute to CAMP resistance by regulating carRS transcription. CarRS is a two-component regulatory system that positively regulates almEFG expression. AlmEFG confers CAMP resistance by glycinylation of lipid A. We found that the expression of carRS and almEFG and the polymyxin B MIC increased in mutants lacking toxRS or leuO Conversely, leuO overexpression decreased the polymyxin B MIC. Furthermore, we found that LeuO directly bound to the carRS promoter and that ToxR-dependent activation of leuO transcription regulated carRS transcription in response to bile salts. Our results suggest that LeuO functions downstream of ToxR to modulate carRS expression in response to environmental cues. This study extends the functional role of ToxR and LeuO in environmental adaptation to include cell surface remodeling and CAMP resistance.
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Affiliation(s)
- X Renee Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, USA
| | - Mondraya F Howard
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, USA
| | - Vanessa M Ante
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, USA
| | - James E Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, USA
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Tipton KA, Farokhyfar M, Rather PN. Multiple roles for a novel RND-type efflux system in Acinetobacter baumannii AB5075. Microbiologyopen 2016; 6. [PMID: 27762102 PMCID: PMC5387308 DOI: 10.1002/mbo3.418] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/09/2016] [Accepted: 09/20/2016] [Indexed: 01/26/2023] Open
Abstract
Colony opacity phase variation in Acinetobacter baumannii strain AB5075 is regulated by a reversible high‐frequency switch. Transposon mutagenesis was used to generate mutations that decreased the opaque to translucent switch and a gene encoding a predicted periplasmic membrane fusion component of a resistance–nodulation–cell division (RND)‐type efflux system was isolated. This gene was designated arpA and immediately downstream was a gene designated arpB that encodes a predicted membrane transporter of RND‐type systems. A nonpolar, in‐frame deletion in arpA resulted in a 70‐fold decrease in the opaque to translucent switch. An arpB::Tc mutant exhibited a 769‐fold decrease in the opaque to translucent switch. However, the translucent to opaque switch was largely unchanged in both the arpA and arpB mutants. The arpA and arpB mutants also exhibited increased surface motility in the opaque form and the arpB mutant exhibited increased susceptibility to aminoglycosides. The arpA and arpB mutants were both attenuated in a Galleria mellonella model of virulence. A divergently transcribed TetR‐type regulator ArpR was capable of repressing the arpAB operon when this TetR regulator was overexpressed. The arpR gene was also involved in regulating the opaque to translucent switch as an in‐frame arpR mutation decreased this switch by 1,916‐fold.
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Affiliation(s)
- Kyle A Tipton
- Department of Microbiology and Immunology, Emory University School of Medicine Atlanta, Atlanta, GA, USA
| | | | - Philip N Rather
- Department of Microbiology and Immunology, Emory University School of Medicine Atlanta, Atlanta, GA, USA.,Research Service, Atlanta VA Medical Center, Decatur, GA, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
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27
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Alcalde-Rico M, Hernando-Amado S, Blanco P, Martínez JL. Multidrug Efflux Pumps at the Crossroad between Antibiotic Resistance and Bacterial Virulence. Front Microbiol 2016; 7:1483. [PMID: 27708632 PMCID: PMC5030252 DOI: 10.3389/fmicb.2016.01483] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 09/06/2016] [Indexed: 01/24/2023] Open
Abstract
Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance), or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance). Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant processes of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals’ and plants’ pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial–host interactions during infection.
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Affiliation(s)
- Manuel Alcalde-Rico
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Sara Hernando-Amado
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Paula Blanco
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - José L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
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28
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Chen B, Yuan K, Chen X, Yang Y, Zhang T, Wang Y, Luan T, Zou S, Li X. Metagenomic Analysis Revealing Antibiotic Resistance Genes (ARGs) and Their Genetic Compartments in the Tibetan Environment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6670-9. [PMID: 27111002 DOI: 10.1021/acs.est.6b00619] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Comprehensive profiles of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in a minimally impacted environment are essential to understanding the evolution and dissemination of modern antibiotic resistance. Chemical analyses of the samples collected from Tibet demonstrated that the region under investigation was almost devoid of anthropogenic antibiotics. The soils, animal wastes, and sediments were different from each other in terms of bacterial community structures, and in the typical profiles of ARGs and MGEs. Diverse ARGs that encoded resistance to common antibiotics (e.g., beta-lactams, fluoroquinolones, etc.) were found mainly via an efflux mechanism completely distinct from modern antibiotic resistome. In addition, a very small fraction of ARGs in the Tibetan environment were carried by MGEs, indicating the low potential of these ARGs to be transferred among bacteria. In comparison to the ARG profiles in relatively pristine Tibet, contemporary ARGs and MGEs in human-impacted environments have evolved substantially since the broad use of anthropogenic antibiotics.
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Affiliation(s)
- Baowei Chen
- South China Sea Resource Exploitation and Protection Collaborative Innovation Center, School of Marine Sciences, Sun Yat-sen University , Guangzhou 510275, China
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University , Hung Hom, Kowloon Hong Kong
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou 510275, China
| | - Ke Yuan
- MOE Key Laboratory of Aquatic Product Safety, School of Life Sciences, Sun Yat-Sen University , Guangzhou 510275, China
| | - Xin Chen
- South China Sea Resource Exploitation and Protection Collaborative Innovation Center, School of Marine Sciences, Sun Yat-sen University , Guangzhou 510275, China
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University , Guangzhou 510275, China
| | - Ying Yang
- South China Sea Resource Exploitation and Protection Collaborative Innovation Center, School of Marine Sciences, Sun Yat-sen University , Guangzhou 510275, China
| | - Tong Zhang
- Environmental Biotechnology Laboratory, The University of Hong Kong , Pokfulam, Hong Kong
| | - Yawei Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center of Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Tiangang Luan
- MOE Key Laboratory of Aquatic Product Safety, School of Life Sciences, Sun Yat-Sen University , Guangzhou 510275, China
| | - Shichun Zou
- South China Sea Resource Exploitation and Protection Collaborative Innovation Center, School of Marine Sciences, Sun Yat-sen University , Guangzhou 510275, China
| | - Xiangdong Li
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University , Hung Hom, Kowloon Hong Kong
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Vibrio cholerae leuO Transcription Is Positively Regulated by ToxR and Contributes to Bile Resistance. J Bacteriol 2015; 197:3499-510. [PMID: 26303831 DOI: 10.1128/jb.00419-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/21/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Vibrio cholerae is an aquatic organism and facultative human pathogen that colonizes the small intestine. In the small intestine, V. cholerae is exposed to a variety of antimicrobial compounds, including bile. V. cholerae resistance to bile is multifactorial and includes alterations in the membrane permeability barrier that are mediated by ToxR, a membrane-associated transcription factor. ToxR has also been shown to be required for activation of the LysR family transcription factor leuO in response to cyclic dipeptides. LeuO has been implicated in the regulation of multiple V. cholerae phenotypes, including biofilm production and virulence. In this study, we investigated the effects of bile on leuO expression. We show that leuO transcription increased in response to bile and bile salts but not in response to other detergents. The bile-dependent increase in leuO expression was dependent on ToxR, which was found to bind directly to the leuO promoter. The periplasmic domain of ToxR was required for basal leuO expression and for the bile-dependent induction of both leuO and ompU transcription. V. cholerae mutants that did not express leuO exhibited increased bile susceptibility, suggesting that LeuO contributes to bile resistance. Our collective results demonstrate that ToxR activates leuO expression in response to bile and that LeuO is a component of the ToxR-dependent responses that contribute to bile resistance. IMPORTANCE The success of Vibrio cholerae as a human pathogen is dependent upon its ability to rapidly adapt to changes in its growth environment. Growth in the human gastrointestinal tract requires the expression of genes that provide resistance to host antimicrobial compounds, including bile. In this work, we show for the first time that the LysR family regulator LeuO mediates responses in V. cholerae that contribute to bile resistance.
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The SmeYZ efflux pump of Stenotrophomonas maltophilia contributes to drug resistance, virulence-related characteristics, and virulence in mice. Antimicrob Agents Chemother 2015; 59:4067-73. [PMID: 25918140 DOI: 10.1128/aac.00372-15] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/20/2015] [Indexed: 01/07/2023] Open
Abstract
The resistance-nodulation-division (RND)-type efflux pump is one of the causes of the multidrug resistance of Stenotrophomonas maltophilia. The roles of the RND-type efflux pump in physiological functions and virulence, in addition to antibiotic extrusion, have attracted much attention. In this study, the contributions of the constitutively expressed SmeYZ efflux pump to drug resistance, virulence-related characteristics, and virulence were evaluated. S. maltophilia KJ is a clinical isolate of multidrug resistance. The smeYZ isogenic deletion mutant, KJΔYZ, was constructed by a gene replacement strategy. The antimicrobial susceptibility, virulence-related physiological characteristics, susceptibility to human serum and neutrophils, and in vivo virulence between KJ and KJΔYZ were comparatively assessed. The SmeYZ efflux pump contributed resistance to aminoglycosides and trimethoprim-sulfamethoxazole. Inactivation of smeYZ resulted in attenuation of oxidative stress susceptibility, swimming, flagella formation, biofilm formation, and secreted protease activity. Furthermore, loss of SmeYZ increased susceptibility to human serum and neutrophils and decreased in vivo virulence in a murine model. These findings suggest the possibility of attenuation of the resistance and virulence of S. maltophilia with inhibitors of the SmeYZ efflux pump.
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Li XZ, Plésiat P, Nikaido H. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria. Clin Microbiol Rev 2015; 28:337-418. [PMID: 25788514 PMCID: PMC4402952 DOI: 10.1128/cmr.00117-14] [Citation(s) in RCA: 924] [Impact Index Per Article: 102.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.
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Affiliation(s)
- Xian-Zhi Li
- Human Safety Division, Veterinary Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Patrick Plésiat
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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Taylor DL, Ante VM, Bina XR, Howard MF, Bina JE. Substrate-dependent activation of the Vibrio cholerae vexAB RND efflux system requires vexR. PLoS One 2015; 10:e0117890. [PMID: 25695834 PMCID: PMC4335029 DOI: 10.1371/journal.pone.0117890] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/05/2015] [Indexed: 01/08/2023] Open
Abstract
Vibrio cholerae encodes six resistance-nodulation-division (RND) efflux systems which function in antimicrobial resistance, virulence factor production, and intestinal colonization. Among the six RND efflux systems, VexAB exhibited broad substrate specificity and played a predominant role in intrinsic antimicrobial resistance. The VexAB system was encoded in an apparent three gene operon that included vexR; which encodes an uncharacterized TetR family regulator. In this work we examined the role of vexR in vexRAB expression. We found that VexR bound to the vexRAB promoter and vexR deletion resulted in decreased vexRAB expression and increased susceptibility to VexAB antimicrobial substrates. Substrate-dependent induction of vexRAB was dependent on vexR and episomal vexR expression provided a growth advantage in the presence of the VexAB substrate deoxycholate. The expression of vexRAB increased, in a vexR-dependent manner, in response to the loss of RND efflux activity. This suggested that VexAB may function to export intracellular metabolites. Support for this hypothesis was provided by data showing that vexRAB was upregulated in several metabolic mutants including tryptophan biosynthetic mutants that were predicted to accumulate indole. In addition, vexRAB was found to be upregulated in response to exogenous indole and to contribute to indole resistance. The collective results indicate that vexR is required for vexRAB expression in response to VexAB substrates and that the VexAB RND efflux system modulates the intracellular levels of metabolites that could otherwise accumulate to toxic levels.
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Affiliation(s)
- Dawn L. Taylor
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Vanessa M. Ante
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - X. Renee Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Mondraya F. Howard
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - James E. Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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The Vibrio cholerae Cpx envelope stress response senses and mediates adaptation to low iron. J Bacteriol 2014; 197:262-76. [PMID: 25368298 DOI: 10.1128/jb.01957-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Cpx pathway, a two-component system that employs the sensor histidine kinase CpxA and the response regulator CpxR, regulates crucial envelope stress responses across bacterial species and affects antibiotic resistance. To characterize the CpxR regulon in Vibrio cholerae, the transcriptional profile of the pandemic V. cholerae El Tor C6706 strain was examined upon overexpression of cpxR. Our data show that the Cpx regulon of V. cholerae is enriched in genes encoding membrane-localized and transport proteins, including a large number of genes known or predicted to be iron regulated. Activation of the Cpx pathway further led to the expression of TolC, the major outer membrane pore, and of components of two RND efflux systems in V. cholerae. We show that iron chelation, toxic compounds, or deletion of specific RND efflux components leads to Cpx pathway activation. Furthermore, mutations that eliminate the Cpx response or members of its regulon result in growth phenotypes in the presence of these inducers that, together with Cpx pathway activation, are partially suppressed by iron. Cumulatively, our results suggest that a major function of the Cpx response in V. cholerae is to mediate adaptation to envelope perturbations caused by toxic compounds and the depletion of iron.
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34
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Destoumieux-Garzón D, Duperthuy M, Vanhove AS, Schmitt P, Wai SN. Resistance to Antimicrobial Peptides in Vibrios. Antibiotics (Basel) 2014; 3:540-63. [PMID: 27025756 PMCID: PMC4790380 DOI: 10.3390/antibiotics3040540] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 09/25/2014] [Accepted: 10/08/2014] [Indexed: 12/19/2022] Open
Abstract
Vibrios are associated with a broad diversity of hosts that produce antimicrobial peptides (AMPs) as part of their defense against microbial infections. In particular, vibrios colonize epithelia, which function as protective barriers and express AMPs as a first line of chemical defense against pathogens. Recent studies have shown they can also colonize phagocytes, key components of the animal immune system. Phagocytes infiltrate infected tissues and use AMPs to kill the phagocytosed microorganisms intracellularly, or deliver their antimicrobial content extracellularly to circumvent tissue infection. We review here the mechanisms by which vibrios have evolved the capacity to evade or resist the potent antimicrobial defenses of the immune cells or tissues they colonize. Among their strategies to resist killing by AMPs, primarily vibrios use membrane remodeling mechanisms. In particular, some highly resistant strains substitute hexaacylated Lipid A with a diglycine residue to reduce their negative surface charge, thereby lowering their electrostatic interactions with cationic AMPs. As a response to envelope stress, which can be induced by membrane-active agents including AMPs, vibrios also release outer membrane vesicles to create a protective membranous shield that traps extracellular AMPs and prevents interaction of the peptides with their own membranes. Finally, once AMPs have breached the bacterial membrane barriers, vibrios use RND efflux pumps, similar to those of other species, to transport AMPs out of their cytoplasmic space.
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Affiliation(s)
- Delphine Destoumieux-Garzón
- Ecology of Coastal Marine Systems, CNRS, Ifremer, University of Montpellier, IRD, Place Eugène Bataillon, CC80, 34095 Montpellier, France.
| | - Marylise Duperthuy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden.
| | - Audrey Sophie Vanhove
- Ecology of Coastal Marine Systems, CNRS, Ifremer, University of Montpellier, IRD, Place Eugène Bataillon, CC80, 34095 Montpellier, France.
| | - Paulina Schmitt
- Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, 2373223 Valparaíso, Chile.
| | - Sun Nyunt Wai
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden.
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Bina XR, Wong EA, Bina TF, Bina JE. Construction of a tetracycline inducible expression vector and characterization of its use in Vibrio cholerae. Plasmid 2014; 76:87-94. [PMID: 25451701 DOI: 10.1016/j.plasmid.2014.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 10/14/2014] [Accepted: 10/20/2014] [Indexed: 01/08/2023]
Abstract
We report the construction of a tetracycline inducible expression vector that allows regulated gene expression in the enteric pathogen Vibrio cholerae. The expression vector, named pXB300, contains the tetracycline regulatory elements from Tn10, a multiple cloning site downstream of the tetA promoter and operator sequences, a ColE1 origin of replication, a β-lactamase resistance gene for positive selection, and the hok/sok addiction system for selection in the absence of antibiotic. The function of the tetracycline expression system was demonstrated by cloning lacZ under control of the tetA promoter and quantifying β-galactosidase expression in Escherichia coli and V. cholerae. The utility for pXB300 was documented by complementation of V. cholerae virulence mutants during growth under virulence inducing conditions. The results showed that pXB300 allowed high-level expression of recombinant genes with linear induction in response to the exogenous concentration of the inducer anhydrotetracycline. We further show that pXB300 was reliably maintained in V. cholerae during growth in the absence of antibiotic selection.
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Affiliation(s)
- X Renee Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Eileen A Wong
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Thomas F Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - James E Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
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36
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Reciprocal regulation of resistance-nodulation-division efflux systems and the Cpx two-component system in Vibrio cholerae. Infect Immun 2014; 82:2980-91. [PMID: 24799626 DOI: 10.1128/iai.00025-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Cpx two-component regulatory system has been shown in Escherichia coli to alleviate stress caused by misfolded cell envelope proteins. The Vibrio cholerae Cpx system was previously found to respond to cues distinct from those in the E. coli system, suggesting that this system fulfills a different physiological role in the cholera pathogen. Here, we used microarrays to identify genes that were regulated by the V. cholerae Cpx system. Our observations suggest that the activation of the V. cholerae Cpx system does not induce expression of genes involved in the mitigation of stress generated by misfolded cell envelope proteins but promotes expression of genes involved in antimicrobial resistance. In particular, activation of the Cpx system induced expression of the genes encoding the VexAB and VexGH resistance-nodulation-division (RND) efflux systems and their cognate outer membrane pore protein TolC. The promoters for these loci contained putative CpxR consensus binding sites, and ectopic cpxR expression activated transcription from the promoters for the RND efflux systems. CpxR was not required for intrinsic antimicrobial resistance, but CpxR activation enhanced resistance to antimicrobial substrates of VexAB and VexGH. Mutations that inactivated VexAB or VexGH efflux activity resulted in the activation of the Cpx response, suggesting that vexAB and vexGH and the cpxP-cpxRA system are reciprocally regulated. We speculate that the reciprocal regulation of the V. cholerae RND efflux systems and the Cpx two-component system is mediated by the intracellular accumulation of an endogenously produced metabolic by-product that is normally extruded from the cell by the RND efflux systems.
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37
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Vikram A, Ante VM, Bina XR, Zhu Q, Liu X, Bina JE. Cyclo(valine-valine) inhibits Vibrio cholerae virulence gene expression. MICROBIOLOGY-SGM 2014; 160:1054-1062. [PMID: 24644247 DOI: 10.1099/mic.0.077297-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Vibrio cholerae has been shown to produce a cyclic dipeptide, cyclo(phenylalanine-proline) (cFP), that functions to repress virulence factor production. The objective of this study was to determine if heterologous cyclic dipeptides could repress V. cholerae virulence factor production. To that end, three synthetic cyclic dipeptides that differed in their side chains from cFP were assayed for virulence inhibitory activity in V. cholerae. The results revealed that cyclo(valine-valine) (cVV) inhibited virulence factor production by a ToxR-dependent process that resulted in the repression of the virulence regulator aphA. cVV-dependent repression of aphA was found to be independent of known aphA regulatory genes. The results demonstrated that V. cholerae was able to respond to exogenous cyclic dipeptides and implicated the hydrophobic amino acid side chains on both arms of the cyclo dipeptide scaffold as structural requirements for inhibitory activity. The results further suggest that cyclic dipeptides have potential as therapeutics for cholera treatment.
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Affiliation(s)
- Amit Vikram
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, PA 15219, USA
| | - Vanessa M Ante
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, PA 15219, USA
| | - X Renee Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, PA 15219, USA
| | - Qin Zhu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Xinyu Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - James E Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, PA 15219, USA
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Chen B, Yang Y, Liang X, Yu K, Zhang T, Li X. Metagenomic profiles of antibiotic resistance genes (ARGs) between human impacted estuary and deep ocean sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:12753-12760. [PMID: 24125531 DOI: 10.1021/es403818e] [Citation(s) in RCA: 273] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Knowledge of the origins and dissemination of antibiotic resistance genes (ARGs) is essential for understanding modern resistomes in the environment. The mechanisms of the dissemination of ARGs can be revealed through comparative studies on the metagenomic profiling of ARGs between relatively pristine and human-impacted environments. The deep ocean bed of the South China Sea (SCS) is considered to be largely devoid of anthropogenic impacts, while the Pearl River Estuary (PRE) in south China has been highly impacted by intensive human activities. Commonly used antibiotics (sulfamethazine, norfloxacin, ofloxacin, tetracycline, and erythromycin) have been detected through chemical analysis in the PRE sediments, but not in the SCS sediments. In the relatively pristine SCS sediments, the most prevalent and abundant ARGs are those related to resistance to macrolides and polypeptides, with efflux pumps as the predominant mechanism. In the contaminated PRE sediments, the typical ARG profiles suggest a prevailing resistance to antibiotics commonly used in human health and animal farming (including sulfonamides, fluoroquinolones, and aminoglycosides), and higher diversity in both genotype and resistance mechanism than those in the SCS. In particular, antibiotic inactivation significantly contributed to the resistance to aminoglycosides, β-lactams, and macrolides observed in the PRE sediments. There was a significant correlation in the levels of abundance of ARGs and those of mobile genetic elements (including integrons and plasmids), which serve as carriers in the dissemination of ARGs in the aquatic environment. The metagenomic results from the current study support the view that ARGs naturally originate in pristine environments, while human activities accelerate the dissemination of ARGs so that microbes would be able to tolerate selective environmental stress in response to anthropogenic impacts.
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Affiliation(s)
- Baowei Chen
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong
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Abstract
Vibrio cholerae is an aquatic organism that causes the severe acute diarrheal disease cholera. The ability of V. cholerae to cause disease is dependent upon the production of two critical virulence determinants, cholera toxin (CT) and the toxin-coregulated pilus (TCP). The expression of the genes that encode for CT and TCP production is under the control of a hierarchical regulatory system called the ToxR regulon, which functions to activate virulence gene expression in response to in vivo stimuli. Cyclic dipeptides have been found to be produced by numerous bacteria, yet their biological function remains unknown. V. cholerae has been shown to produce cyclo(Phe-Pro). Previous studies in our laboratory demonstrated that cyclo(Phe-Pro) inhibited V. cholerae virulence factor production. For this study, we report on the mechanism by which cyclo(Phe-Pro) inhibited virulence factor production. We have demonstrated that exogenous cyclo(Phe-Pro) activated the expression of leuO, a LysR-family regulator that had not been previously associated with V. cholerae virulence. Increased leuO expression repressed aphA transcription, which resulted in downregulation of the ToxR regulon and attenuated CT and TCP production. The cyclo(Phe-Pro)-dependent induction of leuO expression was found to be dependent upon the virulence regulator ToxR. Cyclo(Phe-Pro) did not affect toxR transcription or ToxR protein levels but appeared to enhance the ToxR-dependent transcription of leuO. These results have identified leuO as a new component of the ToxR regulon and demonstrate for the first time that ToxR is capable of downregulating virulence gene expression in response to an environmental cue. The ToxR regulon has been a focus of cholera research for more than three decades. During this time, a model has emerged wherein ToxR functions to activate the expression of Vibrio cholerae virulence factors upon host entry. V. cholerae and other enteric bacteria produce cyclo(Phe-Pro), a cyclic dipeptide that we identified as an inhibitor of V. cholerae virulence factor production. This finding suggested that cyclo(Phe-Pro) was a negative effector of virulence factor production and represented a molecule that could potentially be exploited for therapeutic development. In this work, we investigated the mechanism by which cyclo(Phe-Pro) inhibited virulence factor production. We found that cyclo(Phe-Pro) signaled through ToxR to activate the expression of leuO, a new virulence regulator that functioned to repress virulence factor production. Our results have identified a new arm of the ToxR regulon and suggest that ToxR may play a broader role in pathogenesis than previously known.
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40
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Fernando DM, Kumar A. Resistance-Nodulation-Division Multidrug Efflux Pumps in Gram-Negative Bacteria: Role in Virulence. Antibiotics (Basel) 2013; 2:163-81. [PMID: 27029297 PMCID: PMC4790303 DOI: 10.3390/antibiotics2010163] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 01/13/2023] Open
Abstract
Resistance-Nodulation-Division (RND) efflux pumps are one of the most important determinants of multidrug resistance (MDR) in Gram-negative bacteria. With an ever increasing number of Gram-negative clinical isolates exhibiting MDR phenotypes as a result of the activity of RND pumps, it is clear that the design of novel effective clinical strategies against such pathogens must be grounded in a better understanding of these pumps, including their physiological roles. To this end, recent evidence suggests that RND pumps play an important role in the virulence of Gram-negative pathogens. In this review, we discuss the important role RND efflux pumps play in different facets of virulence including colonization, evasion of host defense mechanisms, and biofilm formation. These studies provide key insights that may ultimately be applied towards strategies used in the design of effective therapeutics against MDR Gram negative bacterial pathogens.
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Affiliation(s)
- Dinesh M Fernando
- Antimicrobial Resistance Research Group (ARRG), Applied Bioscience Program, Faculties of Health Sciences and Science, University of Ontario Institute of Technology, 2000 Simcoe Street N, Oshawa, ON L1H 7K4, Canada.
| | - Ayush Kumar
- Antimicrobial Resistance Research Group (ARRG), Applied Bioscience Program, Faculties of Health Sciences and Science, University of Ontario Institute of Technology, 2000 Simcoe Street N, Oshawa, ON L1H 7K4, Canada.
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Alvarez-Ortega C, Olivares J, Martínez JL. RND multidrug efflux pumps: what are they good for? Front Microbiol 2013; 4:7. [PMID: 23386844 PMCID: PMC3564043 DOI: 10.3389/fmicb.2013.00007] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 01/07/2013] [Indexed: 01/27/2023] Open
Abstract
Multidrug efflux pumps are chromosomally encoded genetic elements capable of mediating resistance to toxic compounds in several life forms. In bacteria, these elements are involved in intrinsic and acquired resistance to antibiotics. Unlike other well-known horizontally acquired antibiotic resistance determinants, genes encoding for multidrug efflux pumps belong to the core of bacterial genomes and thus have evolved over millions of years. The selective pressure stemming from the use of antibiotics to treat bacterial infections is relatively recent in evolutionary terms. Therefore, it is unlikely that these elements have evolved in response to antibiotics. In the last years, several studies have identified numerous functions for efflux pumps that go beyond antibiotic extrusion. In this review we present some examples of these functions that range from bacterial interactions with plant or animal hosts, to the detoxification of metabolic intermediates or the maintenance of cellular homeostasis.
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Affiliation(s)
- Carolina Alvarez-Ortega
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
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42
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LysR family activator-regulated major facilitator superfamily transporters are involved in Vibrio cholerae antimicrobial compound resistance and intestinal colonisation. Int J Antimicrob Agents 2013. [DOI: 10.1016/j.ijantimicag.2012.10.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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43
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Szumowski JD, Adams KN, Edelstein PH, Ramakrishnan L. Antimicrobial efflux pumps and Mycobacterium tuberculosis drug tolerance: evolutionary considerations. Curr Top Microbiol Immunol 2013; 374:81-108. [PMID: 23242857 PMCID: PMC3859842 DOI: 10.1007/82_2012_300] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The need for lengthy treatment to cure tuberculosis stems from phenotypic drug resistance, also known as drug tolerance, which has been previously attributed to slowed bacterial growth in vivo. We discuss recent findings that challenge this model and instead implicate macrophage-induced mycobacterial efflux pumps in antimicrobial tolerance. Although mycobacterial efflux pumps may have originally served to protect against environmental toxins, in the pathogenic mycobacteria, they appear to have been repurposed for intracellular growth. In this light, we discuss the potential of efflux pump inhibitors such as verapamil to shorten tuberculosis treatment by their dual inhibition of tolerance and growth.
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Affiliation(s)
- John D Szumowski
- Department of Medicine (Division of Infectious Diseases), University of Washington, Seattle, WA, USA,
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