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Jurėnas D. Metabolic Labeling: Snapshot of the Effect of Toxins on the Key Cellular Processes. Methods Mol Biol 2024; 2715:539-545. [PMID: 37930550 DOI: 10.1007/978-1-0716-3445-5_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Competing bacteria secrete vast variety of toxic effectors via secretion systems. Phospholipase, peptidoglycan-hydrolase, or pore forming toxins often manifest in the bursting of the prey cell. Other toxins reach cytoplasm of the prey where they affect cell division machinery, metabolism, nucleic acid integrity, or protein synthesis. Inhibition of cell division or DNA integrity, which summons SOS response, will often lead to bacterial cell filamentation readily observable under the microscope. However, other toxic activities will not manifest in interpretable phenotypic changes that would readily suggest their mechanism of toxicity. Activity measurements of the three fundamental cellular processes-replication, transcription and translation can pave the way for further understanding of the toxin's activity. Method commonly known as metabolic labeling makes use of radioactive precursors for DNA, RNA and protein synthesis. This method provides highly sensitive snapshot of the activity of key cellular processes.
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Affiliation(s)
- Dukas Jurėnas
- Laboratoire de Génétique et Physiologie Bactérienne, Département de Biologie Moléculaire, Faculté des Sciences, Université Libre de Bruxelles (ULB), Gosselies, Belgium.
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2
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Zhu X, Zhaoyang Zhang, Bin Jia, Yuan Y. Current advances of biocontainment strategy in synthetic biology. Chin J Chem Eng 2022. [DOI: 10.1016/j.cjche.2022.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Conwell M, Dooley J, Naughton PJ. Enterococcal biofilm - a nidus for antibiotic resistance transfer? J Appl Microbiol 2022; 132:3444-3460. [PMID: 34990042 PMCID: PMC9306868 DOI: 10.1111/jam.15441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 08/03/2021] [Accepted: 01/03/2022] [Indexed: 11/30/2022]
Abstract
Enterococci, important agents of hospital acquired infection, are listed on the WHO list of multi-drug resistant pathogens commonly encountered in hospital acquired infections are now of increasing importance, due to the development of strains resistant to multiple antibiotics. Enterococci are also important microorganisms in the environment and their presence is frequently used as an indicator of faecal pollution. Their success is related to their ability to survive within a broad range of habitats and the ease by which they acquire mobile genetic elements, including plasmids, from other bacteria. The enterococci are frequently present within a bacterial biofilm which provides stability and protection to the bacterial population along with an opportunity for a variety of bacterial interactions. Enterococci can accept extrachromosomal DNA both from within its own species and from other bacterial species and this is enhanced by the proximity of the donor and recipient strains. It is this exchange of genetic material that makes the role of biofilm such an important aspect of the success of enterococci. There remain many questions regarding the most suitable model systems to study enterococci in biofilm and regarding the transfer of genetic material including antibiotic resistance in these biofilms. This review focuses on some important aspects of biofilm in the context of horizontal gene transfer (HGT) in enterococci.
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Affiliation(s)
- M Conwell
- The Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Co. Londonderry, BT52 1SA
| | - Jsg Dooley
- The Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Co. Londonderry, BT52 1SA
| | - P J Naughton
- The Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Co. Londonderry, BT52 1SA
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4
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Pinholt M, Bayliss SC, Gumpert H, Worning P, Jensen VVS, Pedersen M, Feil EJ, Westh H. WGS of 1058 Enterococcus faecium from Copenhagen, Denmark, reveals rapid clonal expansion of vancomycin-resistant clone ST80 combined with widespread dissemination of a vanA-containing plasmid and acquisition of a heterogeneous accessory genome. J Antimicrob Chemother 2020; 74:1776-1785. [PMID: 30929020 DOI: 10.1093/jac/dkz118] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 02/25/2019] [Accepted: 02/27/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES From 2012 to 2015, a sudden significant increase in vancomycin-resistant (vanA) Enterococcus faecium (VREfm) was observed in the Capital Region of Denmark. Clonal relatedness of VREfm and vancomycin-susceptible E. faecium (VSEfm) was investigated, transmission events between hospitals were identified and the pan-genome and plasmids from the largest VREfm clonal group were characterized. METHODS WGS of 1058 E. faecium isolates was carried out on the Illumina platform to perform SNP analysis and to identify the pan-genome. One isolate was also sequenced on the PacBio platform to close the genome. Epidemiological data were collected from laboratory information systems. RESULTS Phylogeny of 892 VREfm and 166 VSEfm revealed a polyclonal structure, with a single clonal group (ST80) accounting for 40% of the VREfm isolates. VREfm and VSEfm co-occurred within many clonal groups; however, no VSEfm were related to the dominant VREfm group. A similar vanA plasmid was identified in ≥99% of isolates belonging to the dominant group and 69% of the remaining VREfm. Ten plasmids were identified in the completed genome, and ∼29% of this genome consisted of dispensable accessory genes. The size of the pan-genome among isolates in the dominant group was 5905 genes. CONCLUSIONS Most probably, VREfm emerged owing to importation of a successful VREfm clone which rapidly transmitted to the majority of hospitals in the region whilst simultaneously disseminating a vanA plasmid to pre-existing VSEfm. Acquisition of a heterogeneous accessory genome may account for the success of this clone by facilitating adaptation to new environmental challenges.
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Affiliation(s)
- Mette Pinholt
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Sion C Bayliss
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Heidi Gumpert
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
| | - Peder Worning
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
| | - Veronika V S Jensen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Michael Pedersen
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Department of Clinical Microbiology, Herlev Hospital, Herlev, Denmark
| | - Edward J Feil
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Henrik Westh
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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5
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Wenzler E, Santarossa M, Meyer KA, Harrington AT, Reid GE, Clark NM, Albarillo FS, Bulman ZP. In Vitro Pharmacodynamic Analyses Help Guide the Treatment of Multidrug-Resistant Enterococcus faecium and Carbapenem-Resistant Enterobacter cloacae Bacteremia in a Liver Transplant Patient. Open Forum Infect Dis 2020; 7:ofz545. [PMID: 31993456 PMCID: PMC6978998 DOI: 10.1093/ofid/ofz545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/31/2019] [Indexed: 12/24/2022] Open
Abstract
Background Infections due to multidrug-resistant pathogens are particularly deadly and difficult to treat in immunocompromised patients, where few data exist to guide optimal antimicrobial therapy. In the absence of adequate clinical data, in vitro pharmacokinetic (PK)/pharmacodynamic (PD) analyses can help to design treatment regimens that are bactericidal and may be clinically effective. Methods We report a case in which in vitro pharmacodynamic analyses were utilized to guide the treatment of complex, recurrent bacteremias due to vancomycin-, daptomycin-, and linezolid-resistant Enterococcus faecium and carbapenem-resistant Enterobacter cloacae complex in a liver transplant patient. Results Whole-genome sequencing revealed unique underlying resistance mechanisms and explained the rapid evolution of phenotypic resistance and complicated intrahost genomic dynamics observed in vivo. Performing this comprehensive genotypic and phenotypic testing and time-kill analyses, along with knowledge of institution and patient-specific factors, allowed us to use precision medicine to design a treatment regimen that maximized PK/PD. Conclusions This work provides a motivating example of clinicians and scientists uniting to optimize care in the era of escalating antimicrobial resistance.
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Affiliation(s)
- Eric Wenzler
- College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois, USA
| | | | - Kevin A Meyer
- College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois, USA
| | | | - Gail E Reid
- Loyola University Medical Center, Maywood, Illinois, USA
| | - Nina M Clark
- Loyola University Medical Center, Maywood, Illinois, USA
| | | | - Zackery P Bulman
- College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois, USA
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6
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Oravcova V, Kolar M, Literak I. Highly variable vancomycin-resistant enterococci in the north-eastern part of the Czech Republic. Lett Appl Microbiol 2019; 69:16-22. [DOI: 10.1111/lam.13121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/18/2018] [Accepted: 01/16/2019] [Indexed: 12/19/2022]
Affiliation(s)
- V. Oravcova
- Department of Biology and Wildlife Diseases; Faculty of Veterinary Hygiene and Ecology; University of Veterinary and Pharmaceutical Sciences Brno; Brno Czech Republic
| | - M. Kolar
- Department of Microbiology; Faculty of Medicine and Dentistry; Palacký University Olomouc; Olomouc Czech Republic
| | - I. Literak
- Department of Biology and Wildlife Diseases; Faculty of Veterinary Hygiene and Ecology; University of Veterinary and Pharmaceutical Sciences Brno; Brno Czech Republic
- CEITEC VFU; University of Veterinary and Pharmaceutical Sciences Brno; Brno Czech Republic
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7
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Abstract
The study of the genetics of enterococci has focused heavily on mobile genetic elements present in these organisms, the complex regulatory circuits used to control their mobility, and the antibiotic resistance genes they frequently carry. Recently, more focus has been placed on the regulation of genes involved in the virulence of the opportunistic pathogenic species Enterococcus faecalis and Enterococcus faecium. Little information is available concerning fundamental aspects of DNA replication, partition, and division; this article begins with a brief overview of what little is known about these issues, primarily by comparison with better-studied model organisms. A variety of transcriptional and posttranscriptional mechanisms of regulation of gene expression are then discussed, including a section on the genetics and regulation of vancomycin resistance in enterococci. The article then provides extensive coverage of the pheromone-responsive conjugation plasmids, including sections on regulation of the pheromone response, the conjugative apparatus, and replication and stable inheritance. The article then focuses on conjugative transposons, now referred to as integrated, conjugative elements, or ICEs, and concludes with several smaller sections covering emerging areas of interest concerning the enterococcal mobilome, including nonpheromone plasmids of particular interest, toxin-antitoxin systems, pathogenicity islands, bacteriophages, and genome defense.
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8
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Melegh S, Nyul A, Kovács K, Kovács T, Ghidán Á, Dombrádi Z, Szabó J, Berta B, Lesinszki V, Pászti J, Tóth Á, Mestyán G. Dissemination of VanA-TypeEnterococcus faeciumIsolates in Hungary. Microb Drug Resist 2018; 24:1376-1390. [DOI: 10.1089/mdr.2017.0296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Szilvia Melegh
- Department of Medical Microbiology and Immunology, University of Pécs, Pécs, Hungary
| | - Adrienn Nyul
- Department of Medical Microbiology and Immunology, University of Pécs, Pécs, Hungary
| | - Krisztina Kovács
- Department of Medical Microbiology and Immunology, University of Pécs, Pécs, Hungary
| | | | - Ágoston Ghidán
- Department of Medical Microbiology, Semmelweis University, Budapest, Hungary
| | - Zsuzsanna Dombrádi
- Department of Medical Microbiology, University of Debrecen, Debrecen, Hungary
| | - Judit Szabó
- Department of Medical Microbiology, University of Debrecen, Debrecen, Hungary
| | | | | | - Judit Pászti
- National Public Health Institute, Budapest, Hungary
| | - Ákos Tóth
- National Public Health Institute, Budapest, Hungary
| | - Gyula Mestyán
- Department of Medical Microbiology and Immunology, University of Pécs, Pécs, Hungary
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Partridge SR, Kwong SM, Firth N, Jensen SO. Mobile Genetic Elements Associated with Antimicrobial Resistance. Clin Microbiol Rev 2018; 31:e00088-17. [PMID: 30068738 PMCID: PMC6148190 DOI: 10.1128/cmr.00088-17] [Citation(s) in RCA: 1130] [Impact Index Per Article: 188.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Strains of bacteria resistant to antibiotics, particularly those that are multiresistant, are an increasing major health care problem around the world. It is now abundantly clear that both Gram-negative and Gram-positive bacteria are able to meet the evolutionary challenge of combating antimicrobial chemotherapy, often by acquiring preexisting resistance determinants from the bacterial gene pool. This is achieved through the concerted activities of mobile genetic elements able to move within or between DNA molecules, which include insertion sequences, transposons, and gene cassettes/integrons, and those that are able to transfer between bacterial cells, such as plasmids and integrative conjugative elements. Together these elements play a central role in facilitating horizontal genetic exchange and therefore promote the acquisition and spread of resistance genes. This review aims to outline the characteristics of the major types of mobile genetic elements involved in acquisition and spread of antibiotic resistance in both Gram-negative and Gram-positive bacteria, focusing on the so-called ESKAPEE group of organisms (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), which have become the most problematic hospital pathogens.
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Affiliation(s)
- Sally R Partridge
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney and Westmead Hospital, Westmead, New South Wales, Australia
| | - Stephen M Kwong
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Neville Firth
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Slade O Jensen
- Microbiology and Infectious Diseases, School of Medicine, Western Sydney University, Sydney, New South Wales, Australia
- Antibiotic Resistance & Mobile Elements Group, Ingham Institute for Applied Medical Research, Sydney, New South Wales, Australia
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10
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First description in Europe of the emergence of Enterococcus faecium ST117 carrying both vanA and vanB genes, isolated in Greece. J Glob Antimicrob Resist 2017; 11:68-70. [DOI: 10.1016/j.jgar.2017.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/26/2017] [Accepted: 07/15/2017] [Indexed: 11/17/2022] Open
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11
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Pinholt M, Gumpert H, Bayliss S, Nielsen JB, Vorobieva V, Pedersen M, Feil E, Worning P, Westh H. Genomic analysis of 495 vancomycin-resistant Enterococcus faecium reveals broad dissemination of a vanA plasmid in more than 19 clones from Copenhagen, Denmark. J Antimicrob Chemother 2016; 72:40-47. [PMID: 27605596 DOI: 10.1093/jac/dkw360] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 07/23/2016] [Accepted: 08/02/2016] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVES From 2012 to 2014, there has been a huge increase in vancomycin-resistant (vanA) Enterococcus faecium (VREfm) in Copenhagen, Denmark, with 602 patients infected or colonized with VREfm in 2014 compared with just 22 in 2012. The objective of this study was to describe the genetic epidemiology of VREfm to assess the contribution of clonal spread and horizontal transfer of the vanA transposon (Tn1546) and plasmid in the dissemination of VREfm in hospitals. METHODS VREfm from Copenhagen, Denmark (2012-14) were whole-genome sequenced. The clonal structure was determined and the structure of Tn1546-like transposons was characterized. One VREfm isolate belonging to the largest clonal group was sequenced using long-read technology to close a 37 kb vanA plasmid. RESULTS Phylogeny revealed a polyclonal structure where 495 VREfm isolates were divided into 13 main groups and 7 small groups. The majority of the isolates were located in three groups (n = 44, 100 and 218) and clonal spread of VREfm between wards and hospitals was identified. Five Tn1546-like transposon types were identified. A dominant truncated transposon (type 4, 92%) was spread across all but one VREfm group. The closed vanA plasmid was highly covered by reads from isolates containing the type 4 transposon. CONCLUSIONS This study suggests that it was the dissemination of the type 4 Tn1546-like transposon and plasmid via horizontal transfer to multiple populations of E. faecium, followed by clonal spread of new VREfm clones, that contributed to the increase in and diversity of VREfm in Danish hospitals.
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Affiliation(s)
- Mette Pinholt
- Department of Clinical Microbiology, Hvidovre University Hospital, Hvidovre, Denmark .,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Heidi Gumpert
- Department of Clinical Microbiology, Hvidovre University Hospital, Hvidovre, Denmark
| | - Sion Bayliss
- Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Jesper B Nielsen
- Department of Clinical Microbiology, Hvidovre University Hospital, Hvidovre, Denmark
| | - Veronika Vorobieva
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Michael Pedersen
- Department of Clinical Microbiology, Herlev University Hospital, Herlev, Denmark
| | - Edward Feil
- Department of Biology and Biochemistry, University of Bath, Bath, UK
| | - Peder Worning
- Department of Clinical Microbiology, Hvidovre University Hospital, Hvidovre, Denmark
| | - Henrik Westh
- Department of Clinical Microbiology, Hvidovre University Hospital, Hvidovre, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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12
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Toxin-Antitoxin Systems in Clinical Pathogens. Toxins (Basel) 2016; 8:toxins8070227. [PMID: 27447671 PMCID: PMC4963858 DOI: 10.3390/toxins8070227] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/07/2016] [Indexed: 12/17/2022] Open
Abstract
Toxin-antitoxin (TA) systems are prevalent in bacteria and archaea. Although not essential for normal cell growth, TA systems are implicated in multiple cellular functions associated with survival under stress conditions. Clinical strains of bacteria are currently causing major human health problems as a result of their multidrug resistance, persistence and strong pathogenicity. Here, we present a review of the TA systems described to date and their biological role in human pathogens belonging to the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) and others of clinical relevance (Escherichia coli, Burkholderia spp., Streptococcus spp. and Mycobacterium tuberculosis). Better understanding of the mechanisms of action of TA systems will enable the development of new lines of treatment for infections caused by the above-mentioned pathogens.
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13
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Karlowicz A, Wegrzyn K, Dubiel A, Ropelewska M, Konieczny I. Proteolysis in plasmid DNA stable maintenance in bacterial cells. Plasmid 2016; 86:7-13. [PMID: 27252071 DOI: 10.1016/j.plasmid.2016.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/25/2016] [Accepted: 05/26/2016] [Indexed: 01/12/2023]
Abstract
Plasmids, as extrachromosomal genetic elements, need to work out strategies that promote independent replication and stable maintenance in host bacterial cells. Their maintenance depends on constant formation and dissociation of nucleoprotein complexes formed on plasmid DNA. Plasmid replication initiation proteins (Rep) form specific complexes on direct repeats (iterons) localized within the plasmid replication origin. Formation of these complexes along with a strict control of Rep protein cellular concentration, quaternary structure, and activity, is essential for plasmid maintenance. Another important mechanism for maintenance of low-copy-number plasmids are the toxin-antitoxin (TA) post-segregational killing (psk) systems, which prevent plasmid loss from the bacterial cell population. In this mini review we discuss the importance of nucleoprotein complex processing by energy-dependent host proteases in plasmid DNA replication and plasmid type II toxin-antitoxin psk systems, and draw attention to the elusive role of DNA in this process.
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Affiliation(s)
- Anna Karlowicz
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Katarzyna Wegrzyn
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Andrzej Dubiel
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Malgorzata Ropelewska
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland
| | - Igor Konieczny
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdansk, Poland.
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14
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Abstract
We report the complete genome sequence of a vancomycin-resistant isolate of Enterococcus faecium derived from human feces. The genome comprises one chromosome of 2.9 Mb and three plasmids. The strain harbors a plasmid-borne vanA-type vancomycin resistance locus and is a member of multilocus sequencing type (MLST) cluster ST-17.
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15
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Morroni G, Di Cesare A, Di Sante L, Brenciani A, Vignaroli C, Pasquaroli S, Giovanetti E, Sabatino R, Rossi L, Magnani M, Biavasco F. Enterococcus faecium ST17 from Coastal Marine Sediment Carrying Transferable Multidrug Resistance Plasmids. Microb Drug Resist 2016; 22:523-530. [PMID: 26982016 DOI: 10.1089/mdr.2015.0222] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The multidrug-resistant Enterococcus faecium 17i48, sequence type 17, from marine sediment, carrying erm(B), tet(M), and tet(L) genes, was analyzed for the presence of antibiotic resistance plasmids and for the ability to transfer resistance genes. The strain was found to harbor the replicon type (repA) of pRE25, pRUM, pHTβ, and the axe-txe toxin-antitoxin (TA) system. In mating experiments, tet(M) and tet(L) were cotransferred with the repApRE25, whereas erm(B) was consistently cotransferred with the axe-txe and repApRUM, suggesting that tetracycline and erythromycin resistance genes were carried on different elements both transferable by conjugation, likely via pHTβ-mediated mobilization. Hybridization and PCR mapping demonstrated that tet(M) and tet(L) were located in tandem on a pDO1-like plasmid that also carried the repApRE25, whereas erm(B) was carried by a pRUM-like plasmid. Sequencing of the latter plasmid showed a high nucleotide identity with pRUM and the presence of cat, aadE, sat4, and a complete aphA resistance genes. These findings show that the genetic features of E. faecium 17i48 are consistent with a hospital-adapted clone and suggest that antibiotic resistance may spread in the environment, also in the absence of antibiotic pressure, due to TA system plasmid maintenance.
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Affiliation(s)
- Gianluca Morroni
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche , Ancona, Italy
| | - Andrea Di Cesare
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Laura Di Sante
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Andrea Brenciani
- 1 Department of Biomedical Sciences and Public Health, Polytechnic University of Marche , Ancona, Italy
| | - Carla Vignaroli
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Sonia Pasquaroli
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Eleonora Giovanetti
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
| | - Raffaella Sabatino
- 3 Biochemistry and Molecular Biology Section, Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
| | - Luigia Rossi
- 3 Biochemistry and Molecular Biology Section, Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
| | - Mauro Magnani
- 3 Biochemistry and Molecular Biology Section, Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
| | - Francesca Biavasco
- 2 Department of Life and Environmental Sciences, Polytechnic University of Marche , Ancona, Italy
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16
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The Plasmidome of Firmicutes: Impact on the Emergence and the Spread of Resistance to Antimicrobials. Microbiol Spectr 2016; 3:PLAS-0039-2014. [PMID: 26104702 DOI: 10.1128/microbiolspec.plas-0039-2014] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The phylum Firmicutes is one of the most abundant groups of prokaryotes in the microbiota of humans and animals and includes genera of outstanding relevance in biomedicine, health care, and industry. Antimicrobial drug resistance is now considered a global health security challenge of the 21st century, and this heterogeneous group of microorganisms represents a significant part of this public health issue.The presence of the same resistant genes in unrelated bacterial genera indicates a complex history of genetic interactions. Plasmids have largely contributed to the spread of resistance genes among Staphylococcus, Enterococcus, and Streptococcus species, also influencing the selection and ecological variation of specific populations. However, this information is fragmented and often omits species outside these genera. To date, the antimicrobial resistance problem has been analyzed under a "single centric" perspective ("gene tracking" or "vehicle centric" in "single host-single pathogen" systems) that has greatly delayed the understanding of gene and plasmid dynamics and their role in the evolution of bacterial communities.This work analyzes the dynamics of antimicrobial resistance genes using gene exchange networks; the role of plasmids in the emergence, dissemination, and maintenance of genes encoding resistance to antimicrobials (antibiotics, heavy metals, and biocides); and their influence on the genomic diversity of the main Gram-positive opportunistic pathogens under the light of evolutionary ecology. A revision of the approaches to categorize plasmids in this group of microorganisms is given using the 1,326 fully sequenced plasmids of Gram-positive bacteria available in the GenBank database at the time the article was written.
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17
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Brodrick HJ, Raven KE, Harrison EM, Blane B, Reuter S, Török ME, Parkhill J, Peacock SJ. Whole-genome sequencing reveals transmission of vancomycin-resistant Enterococcus faecium in a healthcare network. Genome Med 2016; 8:4. [PMID: 26759031 PMCID: PMC4709893 DOI: 10.1186/s13073-015-0259-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/29/2015] [Indexed: 08/30/2023] Open
Abstract
Background Bacterial whole-genome sequencing (WGS) has the potential to identify reservoirs of multidrug-resistant organisms and transmission of these pathogens across healthcare networks. We used WGS to define transmission of vancomycin-resistant enterococci (VRE) within a long-term care facility (LTCF), and between this and an acute hospital in the United Kingdom (UK). Methods A longitudinal prospective observational study of faecal VRE carriage was conducted in a LTCF in Cambridge, UK. Stool samples were collected at recruitment, and then repeatedly until the end of the study period, discharge or death. Selective culture media were used to isolate VRE, which were subsequently sequenced and analysed. We also analysed the genomes of 45 Enterococcus faecium bloodstream isolates collected at Cambridge University Hospitals NHS Foundation Trust (CUH). Results Forty-five residents were recruited during a 6-month period in 2014, and 693 stools were collected at a frequency of at least 1 week apart. Fifty-one stool samples from 3/45 participants (7 %) were positive for vancomycin-resistant E. faecium. Two residents carried multiple VRE lineages, and one carried a single VRE lineage. Genome analyses based on single nucleotide polymorphisms (SNPs) in the core genome indicated that VRE carried by each of the three residents were unrelated. Participants had extensive contact with the local healthcare network. We found that VRE genomes from LTCF residents and hospital-associated bloodstream infection were interspersed throughout the phylogenetic tree, with several instances of closely related VRE strains from the two settings. Conclusions A proportion of LTCF residents are long-term carriers of VRE. Evidence for genetic relatedness between these and VRE associated with bloodstream infection in a nearby acute NHS Trust indicate a shared bacterial population. Electronic supplementary material The online version of this article (doi:10.1186/s13073-015-0259-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hayley J Brodrick
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Kathy E Raven
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Ewan M Harrison
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Beth Blane
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Sandra Reuter
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - M Estée Török
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK. .,Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, CB2 0QQ, UK. .,Cambridge Public Health England Microbiology and Public Health Laboratory, Box 157, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.
| | - Sharon J Peacock
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Box 157, Hills Road, Cambridge, CB2 0QQ, UK. .,Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, CB2 0QQ, UK. .,Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK. .,London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.
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18
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The Mycobacterium tuberculosis relBE toxin:antitoxin genes are stress-responsive modules that regulate growth through translation inhibition. J Microbiol 2015; 53:783-95. [PMID: 26502963 DOI: 10.1007/s12275-015-5333-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/30/2015] [Accepted: 10/05/2015] [Indexed: 12/11/2022]
Abstract
Toxin-antitoxin (TA) genes are ubiquitous among bacteria and are associated with persistence and dormancy. Following exposure to unfavorable environmental stimuli, several species (Escherichia coli, Staphylococcus aureus, Myxococcus xanthus) employ toxin proteins such as RelE and MazF to downregulate growth or initiate cell death. Mycobacterium tuberculosis possesses three Rel TA modules (Rel Mtb ): RelBE Mtb , RelFG Mtb and RelJK Mtb (Rv1246c-Rv1247c, Rv2865-Rv2866, and Rv3357-Rv3358, respectively), which inhibit mycobacterial growth when the toxin gene (relE, relG, relK) is expressed independently of the antitoxin gene (relB, relF, relJ). In the present study, we examined the in vivo mechanism of the RelE Mtb toxin protein, the impact of RelE Mtb on M. tuberculosis physiology and the environmental conditions that regulate all three rel Mtb modules. RelE Mtb negatively impacts growth and the structural integrity of the mycobacterial envelope, generating cells with aberrant forms that are prone to extensive aggregation. At a time coincident with growth defects, RelE Mtb mediates mRNA degradation in vivo resulting in significant changes to the proteome. We establish that rel Mtb modules are stress responsive, as all three operons are transcriptionally activated following mycobacterial exposure to oxidative stress or nitrogen-limiting growth environments. Here we present evidence that the rel Mtb toxin:antitoxin family is stress-responsive and, through the degradation of mRNA, the RelE Mtb toxin influences the growth, proteome and morphology of mycobacterial cells.
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19
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Characterization of an Enterococcus gallinarum Isolate Carrying a Dual vanA and vanB Cassette. J Clin Microbiol 2015; 53:2225-9. [PMID: 25948610 DOI: 10.1128/jcm.03267-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 04/29/2015] [Indexed: 11/20/2022] Open
Abstract
The ability of vancomycin resistance determinants to be horizontally transferred within enterococci species is a concern. Identification and characterization of vancomycin-resistant enterococci (VRE) in a clinical isolate have a significant impact on infection control practices. In this study, we describe a clinical isolate of Enterococcus gallinarum exhibiting high-level resistance to vancomycin and teicoplanin. The genetic characterization of this isolate showed the presence of vanA and vanB genes in addition to the naturally carried vanC gene. vanA was identified on pA6981, a 35,608-bp circular plasmid with significant homology to plasmid pS177. The vanB operon was integrated into the bacterial chromosome and showed a high level of homology to previously reported Tn1549 and Tn5382. To the best of our knowledge, this is the first report of E. gallinarum carrying both vanA and vanB operons, indicating the importance of identifying the vancomycin resistance mechanism in non-E. faecium and non-E. faecalis enterococcal species.
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20
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Mikalsen T, Pedersen T, Willems R, Coque TM, Werner G, Sadowy E, van Schaik W, Jensen LB, Sundsfjord A, Hegstad K. Investigating the mobilome in clinically important lineages of Enterococcus faecium and Enterococcus faecalis. BMC Genomics 2015; 16:282. [PMID: 25885771 PMCID: PMC4438569 DOI: 10.1186/s12864-015-1407-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/27/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The success of Enterococcus faecium and E. faecalis evolving as multi-resistant nosocomial pathogens is associated with their ability to acquire and share adaptive traits, including antimicrobial resistance genes encoded by mobile genetic elements (MGEs). Here, we investigate this mobilome in successful hospital associated genetic lineages, E. faecium sequence type (ST)17 (n=10) and ST78 (n=10), E. faecalis ST6 (n=10) and ST40 (n=10) by DNA microarray analyses. RESULTS The hybridization patterns of 272 representative targets including plasmid backbones (n=85), transposable elements (n=85), resistance determinants (n=67), prophages (n=29) and clustered regularly interspaced short palindromic repeats (CRISPR)-cas sequences (n=6) separated the strains according to species, and for E. faecalis also according to STs. RCR-, Rep_3-, RepA_N- and Inc18-family plasmids were highly prevalent and with the exception of Rep_3, evenly distributed between the species. There was a considerable difference in the replicon profile, with rep 17/pRUM , rep 2/pRE25 , rep 14/EFNP1 and rep 20/pLG1 dominating in E. faecium and rep 9/pCF10 , rep 2/pRE25 and rep 7 in E. faecalis strains. We observed an overall high correlation between the presence and absence of genes coding for resistance towards antibiotics, metals, biocides and their corresponding MGEs as well as their phenotypic antimicrobial susceptibility pattern. Although most IS families were represented in both E. faecalis and E. faecium, specific IS elements within these families were distributed in only one species. The prevalence of IS256-, IS3-, ISL3-, IS200/IS605-, IS110-, IS982- and IS4-transposases was significantly higher in E. faecium than E. faecalis, and that of IS110-, IS982- and IS1182-transposases in E. faecalis ST6 compared to ST40. Notably, the transposases of IS981, ISEfm1 and IS1678 that have only been reported in few enterococcal isolates were well represented in the E. faecium strains. E. faecalis ST40 strains harboured possible functional CRISPR-Cas systems, and still resistance and prophage sequences were generally well represented. CONCLUSIONS The targeted MGEs were highly prevalent among the selected STs, underlining their potential importance in the evolution of hospital-adapted lineages of enterococci. Although the propensity of inter-species horizontal gene transfer (HGT) must be emphasized, the considerable species-specificity of these MGEs indicates a separate vertical evolution of MGEs within each species, and for E. faecalis within each ST.
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Affiliation(s)
- Theresa Mikalsen
- Research group for Host-microbe Interactions, Department of Medical Biology, Faculty of Health Science, UiT - The Arctic University of Norway, Tromsø, Norway.
| | - Torunn Pedersen
- Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
| | - Rob Willems
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Teresa M Coque
- Servicio de Microbiologia, Hospital Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain. .,Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBER-ESP), Madrid, Spain.
| | - Guido Werner
- Division of Nosocomial Pathogens and Antibiotic Resistance, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany.
| | - Ewa Sadowy
- Department of Molecular Microbiology, National Medicines Institute, ul, Chełmska 30/34, 00-725, Warsaw, Poland.
| | - Willem van Schaik
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Lars Bogø Jensen
- Division of Food Microbiologyt, National Food Institute, Danish Technical University, Copenhagen V, Denmark.
| | - Arnfinn Sundsfjord
- Research group for Host-microbe Interactions, Department of Medical Biology, Faculty of Health Science, UiT - The Arctic University of Norway, Tromsø, Norway. .,Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
| | - Kristin Hegstad
- Research group for Host-microbe Interactions, Department of Medical Biology, Faculty of Health Science, UiT - The Arctic University of Norway, Tromsø, Norway. .,Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
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21
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Krügel H, Klimina KM, Mrotzek G, Tretyakov A, Schöfl G, Saluz HP, Brantl S, Poluektova EU, Danilenko VN. Expression of the toxin-antitoxin genes yefM(Lrh), yoeB(Lrh) in human Lactobacillus rhamnosus isolates. J Basic Microbiol 2015; 55:982-91. [PMID: 25832734 DOI: 10.1002/jobm.201400904] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 03/13/2015] [Indexed: 11/07/2022]
Abstract
Lactobacilli are important microorganisms in various activities, for example, diary products, meat ripening, bread and pickles, but, moreover, are associated directly with human skin and cavities (e.g., mouth, gut, or vagina). Some of them are used as probiotics. Therefore, the molecular biological investigation of these bacteria is important. Earlier we described several toxin antitoxin systems (type II) in lactobacilli. Here, we describe the structure and transcriptional regulation of genes, encoding TA system YefM-YoeB(Lrh) in three strains of Lactobacillus rhamnosus comparing stationary and exponential growth phases, the influence of stress factors and mRNA stability. The same TA system is responding to physiological and stress conditions differently in related strains. Using primer extension and RLM-RACE methods we determined three transcription start sites of RNAs in the operon. The promoter region of the operon is preceded by a conserved BOX element occurring at multiple positions in the genomes of L. rhamnosus strains. Downstream of and partially overlapping with the 3' end of the yoeB(Lrh) toxin gene, a divergently transcribed unexpected RNA was detected.
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Affiliation(s)
- Hans Krügel
- Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Jena, Germany
| | - Ksenia M Klimina
- Department of Post-genomic Biotechnology, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Grit Mrotzek
- Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Jena, Germany
| | - Alexander Tretyakov
- Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Jena, Germany
| | - Gerhard Schöfl
- Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Jena, Germany
| | - Hans-Peter Saluz
- Leibniz Institute for Natural Product Research and Infection Biology, Hans-Knöll-Institute, Jena, Germany.,Friedrich-Schiller-University Jena, Jena, Germany
| | | | - Elena U Poluektova
- Department of Post-genomic Biotechnology, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Valery N Danilenko
- Department of Post-genomic Biotechnology, Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
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22
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Vancomycin-variable enterococci can give rise to constitutive resistance during antibiotic therapy. Antimicrob Agents Chemother 2014; 59:1405-10. [PMID: 25512425 DOI: 10.1128/aac.04490-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Vancomycin-resistant enterococci (VRE) are notorious clinical pathogens restricting the use of glycopeptide antibiotics in the clinic setting. Routine surveillance to detect VRE isolated from patients relies on PCR bioassays and chromogenic agar-based test methods. In recent years, we and others have reported the emergence of enterococcal strains harboring a "silent" copy of vancomycin resistance genes that confer a vancomycin-susceptible phenotype (vancomycin-susceptible enterococci [VSE]) and thus escape detection using drug sensitivity screening tests. Alarmingly, these strains are able to convert to a resistance phenotype (VSE→VRE) during antibiotic treatment, severely compromising the success of therapy. Such strains have been termed vancomycin-variable enterococci (VVE). We have investigated the molecular mechanisms leading to the restoration of resistance in VVE isolates through the whole-genome sequencing of resistant isolates, measurement of resistance gene expression, and quantification of the accumulation of drug-resistant peptidoglycan precursors. The results demonstrate that VVE strains can revert to a VRE phenotype through the constitutive expression of the vancomycin resistance cassette. This is accomplished through a variety of changes in the DNA region upstream of the resistance genes that includes both a deletion of a likely transcription inhibitory secondary structure and the introduction of a new unregulated promoter. The VSE→VRE transition of VVE can occur in patients during the course of antibiotic therapy, resulting in treatment failure. These VVE strains therefore pose a new challenge to the current regimen of diagnostic tests used for VRE detection in the clinic setting.
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23
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Outbreak of vancomycin-susceptible Enterococcus faecium containing the wild-type vanA gene. J Clin Microbiol 2014; 52:1682-6. [PMID: 24523464 DOI: 10.1128/jcm.03563-13] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Accurate detection of vancomycin-resistant enterococci (VRE) is essential in preventing transmission in health care settings. Chromogenic media are widely used for screening VRE because of fast turnaround times (TAT) and high sensitivity. We report an outbreak of Enterococcus faecium bearing vanA yet susceptible to vancomycin (vancomycin-variable Enterococcus [VVE]). Between October 2009 to March 2011, clinical and screening specimens (n=14,747) were screened for VRE using VRE-selective medium and/or PCR. VVE isolates were genotyped to determine relatedness. Plasmids from these isolates were characterized by sequencing. Overall, 52 VVE isolates were identified, comprising 15% of all VRE isolates identified. Isolates demonstrated growth on Brilliance VRE agar (Oxoid) at 24 h of incubation but did not grow on brain heart infusion agar with 6 μg/ml vancomycin (Oxoid) or bile esculin azide agar with 6 μg/ml vancomycin (Oxoid) and were susceptible to vancomycin. Genotyping of 20 randomly selected VVE isolates revealed that 15/20 were identical, while 5 were highly related. PCR of the VVE transposon confirmed the presence of vanHAXY gene cluster; however, vanS (sensor) and vanR (regulator) genes were absent. The outbreak was controlled through routine infection control measures. We report an emergence of a fit strain of E. faecium containing vanA yet susceptible to vancomycin. Whether this new strain represents VRE has yet to be determined; however, unique testing procedures are required for reliable identification of VVE.
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24
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Bertram R, Schuster CF. Post-transcriptional regulation of gene expression in bacterial pathogens by toxin-antitoxin systems. Front Cell Infect Microbiol 2014; 4:6. [PMID: 24524029 PMCID: PMC3905216 DOI: 10.3389/fcimb.2014.00006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 01/13/2014] [Indexed: 01/27/2023] Open
Abstract
Toxin-antitoxin (TA) systems are small genetic elements ubiquitous in prokaryotic genomes that encode toxic proteins targeting various vital cellular functions. Typically, toxin activity is controlled by adjacently encoded protein or RNA antitoxins and unleashed as a consequence of genetic fluctuations or stressful conditions. Whereas some TA systems interfere with replication or cell wall synthesis, most of them influence transcriptional and post-transcriptional gene regulation. Antitoxin proteins often act as DNA binding transcriptional regulators and many TA toxins exhibit endoribonuclease activity to selectively degrade different RNA species and thus alter gene expression patterns. Some TA RNases cleave tRNA, tmRNAs or rRNAs, whereas most commonly mRNAs either in association with the ribosome or as free transcripts, are targeted. Examples are provided on how TA toxins differentially shape gene expression in bacterial pathogens by creating specialized ribosomes or by altering the transcriptome and how this may be tied in the control of pathogenicity factors.
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Affiliation(s)
- Ralph Bertram
- Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen Tübingen, Germany
| | - Christopher F Schuster
- Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen Tübingen, Germany
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25
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Larson AS, Hergenrother PJ. Light activation of Staphylococcus aureus toxin YoeBSa1 reveals guanosine-specific endoribonuclease activity. Biochemistry 2013; 53:188-201. [PMID: 24279911 DOI: 10.1021/bi4008098] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Staphylococcus aureus chromosome harbors two homologues of the YefM-YoeB toxin-antitoxin (TA) system. The toxins YoeBSa1 and YoeBSa2 possess ribosome-dependent ribonuclease (RNase) activity in Escherichia coli. This activity is similar to that of the E. coli toxin YoeBEc, an enzyme that, in addition to ribosome-dependent RNase activity, possesses ribosome-independent RNase activity in vitro. To investigate whether YoeBSa1 is also a ribosome-independent RNase, we expressed YoeBSa1 using a novel strategy and characterized its in vitro RNase activity, sequence specificity, and kinetics. Y88 of YoeBSa1 was critical for in vitro activity and cell culture toxicity. This residue was mutated to o-nitrobenzyl tyrosine (ONBY) via unnatural amino acid mutagenesis. YoeBSa1-Y88ONBY could be expressed in the absence of the antitoxin YefMSa1 in E. coli. Photocaged YoeBSa1-Y88ONBY displayed UV light-dependent RNase activity toward free mRNA in vitro. The in vitro ribosome-independent RNase activity of YoeBSa1-Y88ONBY, YoeBSa1-Y88F, and YoeBSa1-Y88TAG was significantly reduced or abolished. In contrast to YoeBEc, which cleaves RNA at both adenosine and guanosine with a preference for adenosine, YoeBSa1 cleaved mRNA specifically at guanosine. Using this information, a fluorometric assay was developed and used to determine the kinetic parameters for ribosome-independent RNA cleavage by YoeBSa1.
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Affiliation(s)
- Amy S Larson
- Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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26
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Połom D, Boss L, Węgrzyn G, Hayes F, Kędzierska B. Amino acid residues crucial for specificity of toxin-antitoxin interactions in the homologous Axe-Txe and YefM-YoeB complexes. FEBS J 2013; 280:5906-18. [PMID: 24028219 DOI: 10.1111/febs.12517] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/30/2013] [Accepted: 09/02/2013] [Indexed: 11/29/2022]
Abstract
Toxin-antitoxin complexes are ubiquitous in bacteria. The specificity of interactions between toxins and antitoxins from homologous but non-interacting systems was investigated. Based on molecular modeling, selected amino acid residues were changed to assess which positions were crucial in the specificity of toxin-antitoxin interaction in the related Axe-Txe and YefM-YoeB complexes. No cross-interactions between wild-type proteins were detected. However, a single amino acid substitution that converts a Txe-specific residue to a YoeB-specific residue reduced, but did not abolish, Txe interaction with the Axe antitoxin. Interestingly, this alteration (Txe-Asp83Tyr) promoted functional interactions between Txe and the YefM antitoxin. The interactions between Txe-Asp83Tyr and YefM were sufficiently strong to abolish Txe toxicity and to allow effective corepression by YefM-Txe-Asp83Tyr of the promoter from which yefM-yoeB is expressed. We conclude that Asp83 in Txe is crucial for the specificity of toxin-antitoxin interactions in the Axe-Txe complex and that swapping this residue for the equivalent residue in YoeB relaxes the specificity of the toxin-antitoxin interaction.
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Affiliation(s)
- Dorota Połom
- Department of Molecular Biology, University of Gdańsk, Poland
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27
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Boss L, Labudda Ł, Węgrzyn G, Hayes F, Kędzierska B. The axe-txe complex of Enterococcus faecium presents a multilayered mode of toxin-antitoxin gene expression regulation. PLoS One 2013; 8:e73569. [PMID: 24019928 PMCID: PMC3760812 DOI: 10.1371/journal.pone.0073569] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/20/2013] [Indexed: 01/25/2023] Open
Abstract
Multidrug-resistant variants of human pathogens from the genus Enterococcus represent a significant health threat as leading agents of nosocomial infections. The easy acquisition of plasmid-borne genes is intimately involved in the spread of antibiotic resistance in enterococci. Toxin-antitoxin (TA) systems play a major role in both maintenance of mobile genetic elements that specify antibiotic resistance, and in bacterial persistence and virulence. Expression of toxin and antitoxin genes must be in balance as inappropriate levels of toxin can be dangerous to the host. The controlled production of toxin and antitoxin is usually achieved by transcriptional autoregulation of TA operons. One of the most prevalent TA modules in enterococcal species is axe-txe which is detected in a majority of clinical isolates. Here, we demonstrate that the axe-txe cassette presents a complex pattern of gene expression regulation. Axe-Txe cooperatively autorepress expression from a major promoter upstream of the cassette. However, an internal promoter that drives the production of a newly discovered transcript from within axe gene combined with a possible modulation in mRNA stability play important roles in the modulation of Axe:Txe ratio to ensure controlled release of the toxin.
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Affiliation(s)
- Lidia Boss
- Department of Molecular Biology, University of Gdańsk, Gdańsk, Poland
| | - Łukasz Labudda
- Department of Molecular Biology, University of Gdańsk, Gdańsk, Poland
| | - Grzegorz Węgrzyn
- Department of Molecular Biology, University of Gdańsk, Gdańsk, Poland
| | - Finbarr Hayes
- Faculty of Life Sciences and Manchester Institute of Biotechnology, the University of Manchester, Manchester, United Kingdom
| | - Barbara Kędzierska
- Department of Molecular Biology, University of Gdańsk, Gdańsk, Poland
- * E-mail:
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28
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van Rensburg JJ, Hergenrother PJ. Detection of endogenous MazF enzymatic activity in Staphylococcus aureus. Anal Biochem 2013; 443:81-7. [PMID: 23994560 DOI: 10.1016/j.ab.2013.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 08/16/2013] [Accepted: 08/18/2013] [Indexed: 10/26/2022]
Abstract
The mazEFSa toxin-antitoxin (TA) system is ubiquitous in clinical isolates of Staphylococcus aureus, yet its physiological role is unclear. MazFSa is a sequence-specific endoribonuclease that inhibits the growth of S. aureus and Escherichia coli on ectopic overexpression. MazFSa preferentially cleaves RNA at UACAU sites, which are overrepresented in genes encoding pathogenicity factors. The exploitation of the inherent toxicity of MazFSa by artificial toxin activation has been proposed as an antibacterial strategy; however, enzymatic activity of endogenous MazFSa has never been detected, and tools for such analyses are lacking. Here we detail methods for detection of the ribonuclease activity of MazFSa, including a continuous fluorometric assay and a gel-based cleavage assay. Importantly, these methods allowed for the first detection of endogenous MazFSa enzymatic activity in S. aureus lysate. These robust and sensitive assays provide a toolkit for the identification, analysis, and validation of stressors that induce MazF enzymatic activity and should assist in the discovery of artificial activators of the mazEFSa TA system.
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Affiliation(s)
- Julia J van Rensburg
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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29
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Nolle N, Schuster CF, Bertram R. Two paralogous yefM-yoeB loci from Staphylococcus equorum encode functional toxin-antitoxin systems. MICROBIOLOGY-SGM 2013; 159:1575-1585. [PMID: 23832005 DOI: 10.1099/mic.0.068049-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Toxin-antitoxin (TA) systems are small genetic elements of prokaryotes associated with persister cell formation, phage defence, stress regulation and programmed cell arrest. In this study, we characterized two paralogues of the ribosome-dependent RNase YefM-YoeB TA system from the Gram-positive organism Staphylococcus equorum SE3. 5' Rapid amplification of cDNA ends confirmed transcriptional activity in the exponential growth phase and revealed an extended 5' untranslated region upstream of the yefM-seq1 gene. Inducible expression of the putative yoeB-seq1/2 toxins led to growth defects of Escherichia coli, which were counteracted by simultaneous induction of the cognate yefM-seq1/2 antitoxin candidates in a strictly pairwise manner. Bacterial two-hybrid assays revealed interaction between YoeB-seq1 and YefM-seq1 but not YoeB-seq1 and YefM-seq2, also indicating two independent systems. In vivo primer extensions demonstrated specific RNA cleavage adjacent to the start codons by YoeB-seq proteins, and YoeB-seq2 activity could be neutralized by the corresponding antitoxin YefM-seq2. Together, these results indicate that the two yefM-yoeB-seq1/2 paralogues from S. equorum encode functional TA systems.
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Affiliation(s)
- Nicoletta Nolle
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin (IMIT), Lehrbereich Mikrobielle Genetik, Waldhäuser Str. 70/8, Eberhard Karls Universität Tübingen, Germany
| | - Christopher F Schuster
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin (IMIT), Lehrbereich Mikrobielle Genetik, Waldhäuser Str. 70/8, Eberhard Karls Universität Tübingen, Germany
| | - Ralph Bertram
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin (IMIT), Lehrbereich Mikrobielle Genetik, Waldhäuser Str. 70/8, Eberhard Karls Universität Tübingen, Germany
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Wright O, Stan GB, Ellis T. Building-in biosafety for synthetic biology. Microbiology (Reading) 2013; 159:1221-1235. [DOI: 10.1099/mic.0.066308-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Oliver Wright
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
| | - Guy-Bart Stan
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
| | - Tom Ellis
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London SW7 2AZ, UK
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Freitas AR, Novais C, Tedim AP, Francia MV, Baquero F, Peixe L, Coque TM. Microevolutionary events involving narrow host plasmids influences local fixation of vancomycin-resistance in Enterococcus populations. PLoS One 2013; 8:e60589. [PMID: 23555993 PMCID: PMC3612099 DOI: 10.1371/journal.pone.0060589] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 02/28/2013] [Indexed: 12/28/2022] Open
Abstract
Vancomycin-resistance in enterococci (VRE) is associated with isolates within ST18, ST17, ST78 Enterococcus faecium (Efm) and ST6 Enterococcus faecalis (Efs) human adapted lineages. Despite of its global spread, vancomycin resistance rates in enterococcal populations greatly vary temporally and geographically. Portugal is one of the European countries where Tn1546 (vanA) is consistently found in a variety of environments. A comprehensive multi-hierarchical analysis of VRE isolates (75 Efm and 29 Efs) from Portuguese hospitals and aquatic surroundings (1996–2008) was performed to clarify the local dynamics of VRE. Clonal relatedness was established by PFGE and MLST while plasmid characterization comprised the analysis of known relaxases, rep initiator proteins and toxin-antitoxin systems (TA) by PCR-based typing schemes, RFLP comparison, hybridization and sequencing. Tn1546 variants were characterized by PCR overlapping/sequencing. Intra- and inter-hospital dissemination of Efm ST18, ST132 and ST280 and Efs ST6 clones, carrying rolling-circle (pEFNP1/pRI1) and theta-replicating (pCIZ2-like, Inc18, pHTβ-like, two pRUM-variants, pLG1-like, and pheromone-responsive) plasmids was documented. Tn1546 variants, mostly containing ISEf1 or IS1216, were located on plasmids (30–150 kb) with a high degree of mosaicism and heterogeneous RFLP patterns that seem to have resulted from the interplay between broad host Inc18 plasmids (pIP501, pRE25, pEF1), and narrow host RepA_N plasmids (pRUM, pAD1-like). TAs of Inc18 (ω-ε-ζ) and pRUM (Axe-Txe) plasmids were infrequently detected. Some plasmid chimeras were persistently recovered over years from different clonal lineages. This work represents the first multi-hierarchical analysis of VRE, revealing a frequent recombinatorial diversification of a limited number of interacting clonal backgrounds, plasmids and transposons at local scale. These interactions provide a continuous process of parapatric clonalization driving a full exploration of the local adaptive landscape, which might assure long-term maintenance of resistant clones and eventually fixation of Tn1546 in particular geographic areas.
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Affiliation(s)
- Ana R. Freitas
- REQUIMTE, Laboratório de Microbiologia, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
| | - Carla Novais
- REQUIMTE, Laboratório de Microbiologia, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Ana P. Tedim
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - María Victoria Francia
- Servicio de Microbiologia, Hospital Universitario Marqués de Valdecilla e Instituto de Formación e Investigación Marqués de Valdecilla (IFIMAV), Santander, Spain
| | - Fernando Baquero
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Luísa Peixe
- REQUIMTE, Laboratório de Microbiologia, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Teresa M. Coque
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
- Unidad de Resistencia a Antibióticos y Virulencia Bacteriana asociada al Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- * E-mail:
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Werner G, Coque TM, Franz CMAP, Grohmann E, Hegstad K, Jensen L, van Schaik W, Weaver K. Antibiotic resistant enterococci-tales of a drug resistance gene trafficker. Int J Med Microbiol 2013; 303:360-79. [PMID: 23602510 DOI: 10.1016/j.ijmm.2013.03.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Enterococci have been recognized as important hospital-acquired pathogens in recent years, and isolates of E. faecalis and E. faecium are the third- to fourth-most prevalent nosocomial pathogen worldwide. Acquired resistances, especially against penicilin/ampicillin, aminoglycosides (high-level) and glycopeptides are therapeutically important and reported in increasing numbers. On the other hand, isolates of E. faecalis and E. faecium are commensals of the intestines of humans, many vertebrate and invertebrate animals and may also constitute an active part of the plant flora. Certain enterococcal isolates are used as starter cultures or supplements in food fermentation and food preservation. Due to their preferred intestinal habitat, their wide occurrence, robustness and ease of cultivation, enterococci are used as indicators for fecal pollution assessing hygiene standards for fresh- and bathing water and they serve as important key indicator bacteria for various veterinary and human resistance surveillance systems. Enterococci are widely prevalent and genetically capable of acquiring, conserving and disseminating genetic traits including resistance determinants among enterococci and related Gram-positive bacteria. In the present review we aimed at summarizing recent advances in the current understanding of the population biology of enterococci, the role mobile genetic elements including plasmids play in shaping the population structure and spreading resistance. We explain how these elements could be classified and discuss mechanisms of plasmid transfer and regulation and the role and cross-talk of enterococcal isolates from food and food animals to humans.
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Affiliation(s)
- Guido Werner
- National Reference Centre for Stapyhlococci and Enterococci, Division of Nosocomial Pathogens and Antibiotic Resistances, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, 38855 Wernigerode, Germany.
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Williams JJ, Hergenrother PJ. Artificial activation of toxin-antitoxin systems as an antibacterial strategy. Trends Microbiol 2012; 20:291-8. [PMID: 22445361 DOI: 10.1016/j.tim.2012.02.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 01/31/2012] [Accepted: 02/13/2012] [Indexed: 11/18/2022]
Abstract
Toxin-antitoxin (TA) systems are unique modules that effect plasmid stabilization via post-segregational killing of the bacterial host. The genes encoding TA systems also exist on bacterial chromosomes, and it has been speculated that these are involved in a variety of cellular processes. Interest in TA systems has increased dramatically over the past 5 years as the ubiquitous nature of TA genes on bacterial genomes has been revealed. The exploitation of TA systems as an antibacterial strategy via artificial activation of the toxin has been proposed and has considerable potential; however, efforts in this area remain in the early stages and several major questions remain. This review investigates the tractability of targeting TA systems to kill bacteria, including fundamental requirements for success, recent advances, and challenges associated with artificial toxin activation.
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Affiliation(s)
- Julia J Williams
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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When ribonucleases come into play in pathogens: a survey of gram-positive bacteria. Int J Microbiol 2012; 2012:592196. [PMID: 22550495 PMCID: PMC3328962 DOI: 10.1155/2012/592196] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 11/27/2011] [Indexed: 11/20/2022] Open
Abstract
It is widely acknowledged that RNA stability plays critical roles in bacterial adaptation and survival in different environments like those encountered when bacteria infect a host. Bacterial ribonucleases acting alone or in concert with regulatory RNAs or RNA binding proteins are the mediators of the regulatory outcome on RNA stability. We will give a current update of what is known about ribonucleases in the model Gram-positive organism Bacillus subtilis and will describe their established roles in virulence in several Gram-positive pathogenic bacteria that are imposing major health concerns worldwide. Implications on bacterial evolution through stabilization/transfer of genetic material (phage or plasmid DNA) as a result of ribonucleases' functions will be covered. The role of ribonucleases in emergence of antibiotic resistance and new concepts in drug design will additionally be discussed.
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Gagnon S, Lévesque S, Lefebvre B, Bourgault AM, Labbé AC, Roger M. vanA-containing Enterococcus faecium susceptible to vancomycin and teicoplanin because of major nucleotide deletions in Tn1546. J Antimicrob Chemother 2011; 66:2758-62. [PMID: 21926081 DOI: 10.1093/jac/dkr379] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES During the course of routine screening for vancomycin-resistant enterococci (VRE), we found six Enterococcus faecium isolates positive for vanA by PCR, but susceptible to vancomycin and teicoplanin by phenotypic testing. The aim of this study was to characterize the genetic composition of the Tn1546 vanA gene cluster of these isolates. METHODS The E. faecium isolates were characterized by antibiotic susceptibility, PFGE and structural analysis of the Tn1546 elements. Plasmids extracted from these isolates were used to determine the presence of the Tn1546 vanA gene cluster by PCR and the genomic organization of the deleted Tn1546 element by primer walking DNA sequencing. RESULTS The vancomycin-susceptible vanA-positive E. faecium isolates showed three PFGE patterns, and were missing the vanR and vanS genes that are responsible for the activation of transcription of resistance genes. Primer walking sequencing revealed that these genes were completely deleted and that interruptions in the vanA cluster were in the vicinity of insertion sequence elements. CONCLUSIONS The presence of vancomycin-susceptible vanA-positive E. faecium in clinical samples results from major deletions in the Tn1546 vanA operon. Our findings support the essential role of vanR and vanS for the expression of resistance to vancomycin in enterococci.
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Affiliation(s)
- Simon Gagnon
- Département de Microbiologie et d'Infectiologie, Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada
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Williams JJ, Halvorsen EM, Dwyer EM, DiFazio RM, Hergenrother PJ. Toxin-antitoxin (TA) systems are prevalent and transcribed in clinical isolates of Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. FEMS Microbiol Lett 2011; 322:41-50. [PMID: 21658105 DOI: 10.1111/j.1574-6968.2011.02330.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The percentage of bacterial infections refractory to standard antibiotic treatments is steadily increasing. Among the most problematic hospital and community-acquired pathogens are methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA). One novel strategy proposed for treating infections of multidrug-resistant bacteria is the activation of latent toxins of toxin-antitoxin (TA) protein complexes residing within bacteria; however, the prevalence and identity of TA systems in clinical isolates of MRSA and PA has not been defined. We isolated DNA from 78 MRSA and 42 PA clinical isolates and used PCR to probe for the presence of various TA loci. Our results showed that the genes for homologs of the mazEF TA system in MRSA and the relBE and higBA TA systems in PA were present in 100% of the respective strains. Additionally, reverse transcriptase PCR analysis revealed that these transcripts are produced in the clinical isolates. These results indicate that TA genes are prevalent and transcribed within MRSA and PA and suggest that activation of the toxin proteins could be an effective antibacterial strategy for these pathogens.
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Affiliation(s)
- Julia J Williams
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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