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Huo W, Price VJ, Sharifi A, Zhang MQ, Palmer KL. Enterococcus faecalis Strains with Compromised CRISPR-Cas Defense Emerge under Antibiotic Selection for a CRISPR-Targeted Plasmid. Appl Environ Microbiol 2023; 89:e0012423. [PMID: 37278656 PMCID: PMC10304774 DOI: 10.1128/aem.00124-23] [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: 01/31/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive bacterium that natively colonizes the human gastrointestinal tract and opportunistically causes life-threatening infections. Multidrug-resistant (MDR) E. faecalis strains have emerged that are replete with mobile genetic elements (MGEs). Non-MDR E. faecalis strains frequently possess CRISPR-Cas systems, which reduce the frequency of MGE acquisition. We demonstrated in previous studies that E. faecalis populations can transiently maintain both a functional CRISPR-Cas system and a CRISPR-Cas target. In this study, we used serial passage and deep sequencing to analyze these populations. In the presence of antibiotic selection for the plasmid, mutants with compromised CRISPR-Cas defense and enhanced ability to acquire a second antibiotic resistance plasmid emerged. Conversely, in the absence of selection, the plasmid was lost from wild-type E. faecalis populations but not E. faecalis populations that lacked the cas9 gene. Our results indicate that E. faecalis CRISPR-Cas can become compromised under antibiotic selection, generating populations with enhanced abilities to undergo horizontal gene transfer. IMPORTANCE Enterococcus faecalis is a leading cause of hospital-acquired infections and disseminator of antibiotic resistance plasmids among Gram-positive bacteria. We have previously shown that E. faecalis strains with an active CRISPR-Cas system can prevent plasmid acquisition and thus limit the transmission of antibiotic resistance determinants. However, CRISPR-Cas is not a perfect barrier. In this study, we observed populations of E. faecalis with transient coexistence of CRISPR-Cas and one of its plasmid targets. Our experimental data demonstrate that antibiotic selection results in compromised E. faecalis CRISPR-Cas function, thereby facilitating the acquisition of additional resistance plasmids by E. faecalis.
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Affiliation(s)
- Wenwen Huo
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Valerie J. Price
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Ardalan Sharifi
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Michael Q. Zhang
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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2
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Shan X, Li XS, Schwarz S, Chen Y, Xu C, Du XD. Plasmid-Assisted Horizontal Transfer of a Large lsa(E)-Carrying Genomic Island in Enterococcus faecalis. Microbiol Spectr 2022; 10:e0015422. [PMID: 35863017 PMCID: PMC9430800 DOI: 10.1128/spectrum.00154-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 06/13/2022] [Indexed: 11/20/2022] Open
Abstract
The horizontal transfer of genomic islands is essential for the adaptation and evolution of Enterococcus faecalis. In this study, three porcine E. faecalis strains, each harboring a large lsa(E)-carrying genomic island, were identified. When using the E. faecalis OG1RF as the recipient, the horizontal transfer of the lsa(E)-carrying genomic island occurred only from E. faecalis E512, which also harbored a pheromone-responsive conjugative plasmid, but not from the other two E. faecalis strains, E533 and E509, which lacked such a plasmid. Subsequently, through plasmid curing of E. faecalis E512 and plasmid introduction into E. faecalis E533, the pheromone-responsive conjugative plasmid was identified to be indispensable for the horizontal transfer of the lsa(E)-carrying genomic island and a subsequent homologous recombination between the chromosomal DNA of the donor and the recipient. In addition, the presence of a chromosomally-located conjugative transposon, Tn916, in E. faecalis E509 could not mediate the horizontal transfer of the lsa(E)-carrying genomic island, although Tn916 itself could transfer by conjugation. Thus, these data highlight the role of the pheromone-responsive conjugative plasmid in the transfer of the lsa(E)-carrying genomic island in E. faecalis, thereby establishing the dual role of pheromone-responsive conjugative plasmids in contributing to the dissemination of both plasmid-borne resistance genes and chromosomally-located genomic islands. IMPORTANCE In this study, it was shown that a pheromone-responsive conjugative plasmid played an indispensable role in the horizontal transfer of a lsa(E)-carrying genomic island. This finding indicates a dual role of the pheromone-responsive conjugative plasmid in disseminating both plasmid-borne resistance genes and chromosomally-located genomic islands. The role of the pheromone-responsive conjugative plasmid in disseminating chromosomal genomic islands is suggested to be essential in the genomic evolution of E. faecalis, which has become one of the leading nosocomial pathogens worldwide.
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Affiliation(s)
- Xinxin Shan
- College of Veterinary Medicine, Zhengzhou, People’s Republic of China
| | - Xin-Sheng Li
- College of Veterinary Medicine, Zhengzhou, People’s Republic of China
| | - Stefan Schwarz
- Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- Veterinary Centre of Resistance Research (TZR), Freie Universität Berlin, Berlin, Germany
| | - Yuxia Chen
- College of Veterinary Medicine, Zhengzhou, People’s Republic of China
| | - Chunyan Xu
- College of Veterinary Medicine, Zhengzhou, People’s Republic of China
| | - Xiang-Dang Du
- College of Veterinary Medicine, Zhengzhou, People’s Republic of China
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3
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Genetic Mechanisms of Vancomycin Resistance in Clostridioides difficile: A Systematic Review. Antibiotics (Basel) 2022; 11:antibiotics11020258. [PMID: 35203860 PMCID: PMC8868222 DOI: 10.3390/antibiotics11020258] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/07/2022] [Accepted: 02/10/2022] [Indexed: 02/01/2023] Open
Abstract
Antimicrobial resistance to treatments for Clostridioides difficile infection (CDI) poses a significant threat to global health. C. difficile is widely thought to be susceptible to oral vancomycin, which is increasingly the mainstay of CDI treatment. However, clinical labs do not conduct C. difficile susceptibility testing, presenting a challenge to detecting the emergence and impact of resistance. In this systematic review, we describe gene determinants and associated clinical and laboratory mechanisms of vancomycin resistance in C. difficile, including drug-binding site alterations, efflux pumps, RNA polymerase mutations, and biofilm formation. Additional research is needed to further characterize these mechanisms and understand their clinical impact.
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Sadowy E. Mobile genetic elements beyond the VanB-resistance dissemination among hospital-associated enterococci and other Gram-positive bacteria. Plasmid 2021; 114:102558. [PMID: 33472048 DOI: 10.1016/j.plasmid.2021.102558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/30/2022]
Abstract
An increasing resistance to vancomycin among clinically relevant enterococci, such as Enterococcus faecalis and Enterococcus faecium is a cause of a great concern, as it seriously limits treatment options. The vanB operon is one of most common determinants of this type of resistance. Genes constituting the operon are located in conjugative transposons, such as Tn1549-type transposons or, more rarely, in ICEEfaV583-type structures. Such elements show differences in structure and size, and reside in various sites of bacterial chromosome or, in the case of Tn1549-type transposons, are also occasionally associated with plasmids of divergent replicon types. While conjugative transposition contributes to the acquisition of Tn1549-type transposons from anaerobic gut commensals by enterococci, chromosomal recombination and conjugal transfer of plasmids appear to represent main mechanisms responsible for horizontal dissemination of vanB determinants among hospital E. faecalis and E. faecium. This review focuses on diversity of genetic elements harbouring vanB determinants in hospital-associated strains of E. faecium and E. faecalis, the mechanisms beyond vanB spread in populations of these bacteria, and provides an overview of the vanB-MGE distribution among other enterococci and Gram-positive bacteria as potential reservoirs of vanB genes.
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Affiliation(s)
- Ewa Sadowy
- Department of Molecular Microbiology, National Medicines Institute, Warsaw, Poland.
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Garcillán-Barcia MP, Cuartas-Lanza R, Cuevas A, de la Cruz F. Cis-Acting Relaxases Guarantee Independent Mobilization of MOB Q 4 Plasmids. Front Microbiol 2019; 10:2557. [PMID: 31781067 PMCID: PMC6856555 DOI: 10.3389/fmicb.2019.02557] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 10/23/2019] [Indexed: 12/16/2022] Open
Abstract
Plasmids are key vehicles of horizontal gene transfer and contribute greatly to bacterial genome plasticity. In this work, we studied a group of plasmids from enterobacteria that encode phylogenetically related mobilization functions that populate the previously non-described MOBQ4 relaxase family. These plasmids encode two transfer genes: mobA coding for the MOBQ4 relaxase; and mobC, which is non-essential but enhances the plasmid mobilization frequency. The origin of transfer is located between these two divergently transcribed mob genes. We found that MPFI conjugative plasmids were the most efficient helpers for MOBQ4 conjugative dissemination among clinically relevant enterobacteria. While highly similar in their mobilization module, two sub-groups with unrelated replicons (Rep_3 and ColE2) can be distinguished in this plasmid family. These subgroups can stably coexist (are compatible) and transfer independently, despite origin-of-transfer cross-recognition by their relaxases. Specific discrimination among their highly similar oriT sequences is guaranteed by the preferential cis activity of the MOBQ4 relaxases. Such a strategy would be biologically relevant in a scenario of co-residence of non-divergent elements to favor self-dissemination.
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Affiliation(s)
- M Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria - Consejo Superior de Investigaciones Científicas), Santander, Spain
| | - Raquel Cuartas-Lanza
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria - Consejo Superior de Investigaciones Científicas), Santander, Spain
| | - Ana Cuevas
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria - Consejo Superior de Investigaciones Científicas), Santander, Spain
| | - Fernando de la Cruz
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria - Consejo Superior de Investigaciones Científicas), Santander, Spain
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Wu Y, Yang L, Li WG, Zhang WZ, Liu ZJ, Lu JX. Microevolution within ST11 group Clostridioides difficile isolates through mobile genetic elements based on complete genome sequencing. BMC Genomics 2019; 20:796. [PMID: 31666016 PMCID: PMC6822371 DOI: 10.1186/s12864-019-6184-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 10/15/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Clade 5 Clostridioides difficile diverges significantly from the other clades and is therefore, attracting increasing attention due its great heterogeneity. In this study, we used third-generation sequencing techniques to sequence the complete whole genomes of three ST11 C. difficile isolates, RT078 and another two new ribotypes (RTs), obtained from three independent hospitalized elderly patients undergoing antibiotics treatment. Mobile genetic elements (MGEs), antibiotic-resistance, drug resistance genes, and virulent-related genes were analyzed and compared within these three isolates. RESULTS Isolates 10,010 and 12,038 carried a distinct deletion in tcdA compared with isolate 21,062. Furthermore, all three isolates had identical deletions and point-mutations in tcdC, which was once thought to be a unique characteristic of RT078. Isolate 21,062 (RT078) had a unique plasmid, different numbers of transposons and genetic organization, and harboring special CRISPR spacers. All three isolates retained high-level sensitivity to 11 drugs and isolate 21,062 (RT078) carried distinct drug-resistance genes and loss of numerous flagellum-related genes. CONCLUSIONS We concluded that capillary electrophoresis based PCR-ribotyping is important for confirming RT078. Furthermore, RT078 isolates displayed specific MGEs, indicating an independent evolutionary process. In the further study, we could testify these findings with more RT078 isolates of divergent origins.
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Affiliation(s)
- Yuan Wu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China. .,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
| | - Lin Yang
- BGI-Shen zhen, main building, Beishan industry zone, Yan tian District, Shenzhen, China
| | - Wen-Ge Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Wen Zhu Zhang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zheng Jie Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jin-Xing Lu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China. .,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
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7
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Verdonk CJ, Sullivan JT, Williman KM, Nicholson L, Bastholm TR, Hynes MF, Ronson CW, Bond CS, Ramsay JP. Delineation of the integrase-attachment and origin-of-transfer regions of the symbiosis island ICEMlSymR7A. Plasmid 2019; 104:102416. [DOI: 10.1016/j.plasmid.2019.102416] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/12/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022]
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Independent Microevolution Mediated by Mobile Genetic Elements of Individual Clostridium difficile Isolates from Clade 4 Revealed by Whole-Genome Sequencing. mSystems 2019; 4:mSystems00252-18. [PMID: 30944881 PMCID: PMC6435816 DOI: 10.1128/msystems.00252-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/18/2019] [Indexed: 12/15/2022] Open
Abstract
Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates. Horizontal gene transfer of mobile genetic elements (MGEs) accounts for the mosaic genome of Clostridium difficile, leading to acquisition of new phenotypes, including drug resistance and reconstruction of the genomes. MGEs were analyzed according to the whole-genome sequences of 37 C. difficile isolates with a variety of sequence types (STs) within clade 4 from China. Great diversity was found in each transposon even within isolates with the same ST. Two novel transposons were identified in isolates ZR9 and ZR18, of which approximately one third to half of the genes showed heterogenous origins compared with the usual intestinal bacterial genes. Most importantly, catD, known to be harbored by Tn4453a/b, was replaced by aac(6′) aph(2′′) in isolates 2, 7, and 28. This phenomenon illustrated the frequent occurrence of gene exchanges between C. difficile and other enterobacteria with individual heterogeneity. Numerous prophages and CRISPR arrays were identified in C. difficile isolates of clade 4. Approximately 20% of spacers were located in prophage-carried CRISPR arrays, providing a new method for typing and tracing the origins of closely related isolates, as well as in-depth studies of the mechanism underlying genome remodeling. The rates of drug resistance were obviously higher than those reported previously around the world, although all isolates retained high sensitivity to vancomycin and metronidazole. The increasing number of C. difficile isolates resistant to all antibiotics tested here suggests the ease with which resistance is acquired in vivo. This study gives insights into the genetic mechanism of microevolution within clade 4. IMPORTANCE Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates.
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9
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Kiss J, Szabó M, Hegyi A, Douard G, Praud K, Nagy I, Olasz F, Cloeckaert A, Doublet B. Identification and Characterization of oriT and Two Mobilization Genes Required for Conjugative Transfer of Salmonella Genomic Island 1. Front Microbiol 2019; 10:457. [PMID: 30894848 PMCID: PMC6414798 DOI: 10.3389/fmicb.2019.00457] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 02/20/2019] [Indexed: 11/13/2022] Open
Abstract
The integrative mobilizable elements of SGI1-family considerably contribute to the spread of resistance to critically important antibiotics among enteric bacteria. Even though many aspects of SGI1 mobilization by IncA and IncC plasmids have been explored, the basic transfer elements such as oriT and self-encoded mobilization proteins remain undiscovered. Here we describe the mobilization region of SGI1 that is well conserved throughout the family and carries the oriT SGI1 and two genes, mpsA and mpsB (originally annotated as S020 and S019, respectively) that are essential for the conjugative transfer of SGI1. OriT SGI1, which is located in the vicinity of the two mobilization genes proved to be a 125-bp GC-rich sequence with several important inverted repeat motifs. The mobilization proteins MpsA and MpsB are expressed from a bicistronic mRNA, although MpsB can be produced from its own mRNA as well. The protein structure predictions imply that MpsA belongs to the lambda tyrosine recombinase family, while MpsB resembles the N-terminal core DNA binding domains of these enzymes. The results suggest that MpsA may act as an atypical relaxase, which needs MpsB for SGI1 transfer. Although the helper plasmid-encoded relaxase proved not to be essential for SGI1 transfer, it appeared to be important to achieve the high transfer rate of the island observed with the IncA/IncC-SGI1 system.
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Affiliation(s)
- János Kiss
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllõ, Hungary
| | - Mónika Szabó
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllõ, Hungary
| | - Anna Hegyi
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllõ, Hungary.,ISP, Institut National de la Recherche Agronomique, Université de Tours, UMR 1282, Nouzilly, France
| | - Gregory Douard
- ISP, Institut National de la Recherche Agronomique, Université de Tours, UMR 1282, Nouzilly, France
| | - Karine Praud
- ISP, Institut National de la Recherche Agronomique, Université de Tours, UMR 1282, Nouzilly, France
| | - István Nagy
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllõ, Hungary
| | - Ferenc Olasz
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllõ, Hungary
| | - Axel Cloeckaert
- ISP, Institut National de la Recherche Agronomique, Université de Tours, UMR 1282, Nouzilly, France
| | - Benoît Doublet
- ISP, Institut National de la Recherche Agronomique, Université de Tours, UMR 1282, Nouzilly, France
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10
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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: 1159] [Impact Index Per Article: 193.2] [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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Evaluation of Virulence Factors and Detection of vanA, vanB and esp Genes from Clinical Isolates of Vancomycin - Resistant Enterococcus faecalis. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2018. [DOI: 10.22207/jpam.12.2.23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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12
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Rubio-Cosials A, Schulz EC, Lambertsen L, Smyshlyaev G, Rojas-Cordova C, Forslund K, Karaca E, Bebel A, Bork P, Barabas O. Transposase-DNA Complex Structures Reveal Mechanisms for Conjugative Transposition of Antibiotic Resistance. Cell 2018; 173:208-220.e20. [PMID: 29551265 PMCID: PMC5871717 DOI: 10.1016/j.cell.2018.02.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/08/2018] [Accepted: 02/12/2018] [Indexed: 12/28/2022]
Abstract
Conjugative transposition drives the emergence of multidrug resistance in diverse bacterial pathogens, yet the mechanisms are poorly characterized. The Tn1549 conjugative transposon propagates resistance to the antibiotic vancomycin used for severe drug-resistant infections. Here, we present four high-resolution structures of the conserved Y-transposase of Tn1549 complexed with circular transposon DNA intermediates. The structures reveal individual transposition steps and explain how specific DNA distortion and cleavage mechanisms enable DNA strand exchange with an absolute minimum homology requirement. This appears to uniquely allow Tn916-like conjugative transposons to bypass DNA homology and insert into diverse genomic sites, expanding gene transfer. We further uncover a structural regulatory mechanism that prevents premature cleavage of the transposon DNA before a suitable target DNA is found and generate a peptide antagonist that interferes with the transposase-DNA structure to block transposition. Our results reveal mechanistic principles of conjugative transposition that could help control the spread of antibiotic resistance genes. Antibiotic resistance-carrying conjugative transposon integrase structure revealed DNA distortion and special cleavage site allow insertion into diverse genomic sites Key structural features are conserved among numerous conjugative transposons Structures uncover auto-inhibition, allowing transposition antagonist design
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Affiliation(s)
- Anna Rubio-Cosials
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Eike C Schulz
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Hamburg Outstation, European Molecular Biology Laboratory, 22603 Hamburg, Germany
| | - Lotte Lambertsen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Georgy Smyshlyaev
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; European Bioinformatics Institute (EMBL-EBI), European Molecular Biology Laboratory, Hinxton CB10 1SD, UK
| | - Carlos Rojas-Cordova
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Kristoffer Forslund
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Ezgi Karaca
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Izmir Biomedicine and Genome Center (IBG), 35340 Izmir, Turkey
| | - Aleksandra Bebel
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Peer Bork
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany; Molecular Medicine Partnership Unit, 69120 Heidelberg, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Orsolya Barabas
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
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13
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Ahmed MO, Baptiste KE. Vancomycin-Resistant Enterococci: A Review of Antimicrobial Resistance Mechanisms and Perspectives of Human and Animal Health. Microb Drug Resist 2017; 24:590-606. [PMID: 29058560 DOI: 10.1089/mdr.2017.0147] [Citation(s) in RCA: 220] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Vancomycin-resistant enterococci (VRE) are both of medical and public health importance associated with serious multidrug-resistant infections and persistent colonization. Enterococci are opportunistic environmental inhabitants with a remarkable adaptive capacity to evolve and transmit antimicrobial-resistant determinants. The VRE gene operons show distinct genetic variability and apparently continued evolution leading to a variety of antimicrobial resistance phenotypes and various environmental and livestock reservoirs for the most common van genes. Such complex diversity renders a number of important therapeutic options including "last resort antibiotics" ineffective and poses a particular challenge for clinical management. Enterococci resistance to glycopeptides and multidrug resistance warrants attention and continuous monitoring.
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Affiliation(s)
- Mohamed O Ahmed
- 1 Department of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Tripoli , Tripoli, Libya
| | - Keith E Baptiste
- 2 Department of Veterinary Medicine, Danish Medicines Agency , Copenhagen South, Denmark
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14
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Polyvalent Proteins, a Pervasive Theme in the Intergenomic Biological Conflicts of Bacteriophages and Conjugative Elements. J Bacteriol 2017; 199:JB.00245-17. [PMID: 28559295 PMCID: PMC5512222 DOI: 10.1128/jb.00245-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/17/2017] [Indexed: 12/29/2022] Open
Abstract
Intense biological conflicts between prokaryotic genomes and their genomic parasites have resulted in an arms race in terms of the molecular “weaponry” deployed on both sides. Using a recursive computational approach, we uncovered a remarkable class of multidomain proteins with 2 to 15 domains in the same polypeptide deployed by viruses and plasmids in such conflicts. Domain architectures and genomic contexts indicate that they are part of a widespread conflict strategy involving proteins injected into the host cell along with parasite DNA during the earliest phase of infection. Their unique feature is the combination of domains with highly disparate biochemical activities in the same polypeptide; accordingly, we term them polyvalent proteins. Of the 131 domains in polyvalent proteins, a large fraction are enzymatic domains predicted to modify proteins, target nucleic acids, alter nucleotide signaling/metabolism, and attack peptidoglycan or cytoskeletal components. They further contain nucleic acid-binding domains, virion structural domains, and 40 novel uncharacterized domains. Analysis of their architectural network reveals both pervasive common themes and specialized strategies for conjugative elements and plasmids or (pro)phages. The themes include likely processing of multidomain polypeptides by zincin-like metallopeptidases and mechanisms to counter restriction or CRISPR/Cas systems and jump-start transcription or replication. DNA-binding domains acquired by eukaryotes from such systems have been reused in XPC/RAD4-dependent DNA repair and mitochondrial genome replication in kinetoplastids. Characterization of the novel domains discovered here, such as RNases and peptidases, are likely to aid in the development of new reagents and elucidation of the spread of antibiotic resistance. IMPORTANCE This is the first report of the widespread presence of large proteins, termed polyvalent proteins, predicted to be transmitted by genomic parasites such as conjugative elements, plasmids, and phages during the initial phase of infection along with their DNA. They are typified by the presence of multiple domains with disparate activities combined in the same protein. While some of these domains are predicted to assist the invasive element in replication, transcription, or protection of their DNA, several are likely to target various host defense systems or modify the host to favor the parasite's life cycle. Notably, DNA-binding domains from these systems have been transferred to eukaryotes, where they have been incorporated into DNA repair and mitochondrial genome replication systems.
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Homologous Recombination within Large Chromosomal Regions Facilitates Acquisition of β-Lactam and Vancomycin Resistance in Enterococcus faecium. Antimicrob Agents Chemother 2016; 60:5777-86. [PMID: 27431230 PMCID: PMC5038250 DOI: 10.1128/aac.00488-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 07/06/2016] [Indexed: 02/06/2023] Open
Abstract
The transfer of DNA between Enterococcus faecium strains has been characterized both by the movement of well-defined genetic elements and by the large-scale transfer of genomic DNA fragments. In this work, we report on the whole-genome analysis of transconjugants resulting from mating events between the vancomycin-resistant E. faecium C68 strain and the vancomycin-susceptible D344RRF strain to discern the mechanism by which the transferred regions enter the recipient chromosome. Vancomycin-resistant transconjugants from five independent matings were analyzed by whole-genome sequencing. In all cases but one, the penicillin binding protein 5 (pbp5) gene and the Tn5382 vancomycin resistance transposon were transferred together and replaced the corresponding pbp5 region of D344RRF. In one instance, Tn5382 inserted independently downstream of the D344RRF pbp5 gene. Single nucleotide variant (SNV) analysis suggested that entry of donor DNA into the recipient chromosome occurred by recombination across regions of homology between donor and recipient chromosomes, rather than through insertion sequence-mediated transposition. The transfer of genomic DNA was also associated with the transfer of C68 plasmid pLRM23 and another putative plasmid. Our data are consistent with the initiation of transfer by cointegration of a transferable plasmid with the donor chromosome, with subsequent circularization of the plasmid-chromosome cointegrant in the donor prior to transfer. Entry into the recipient chromosome most commonly occurred across regions of homology between donor and recipient chromosomes.
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Hansen TA, Joshi T, Larsen AR, Andersen PS, Harms K, Mollerup S, Willerslev E, Fuursted K, Nielsen LP, Hansen AJ. Vancomycin gene selection in the microbiome of urban Rattus norvegicus from hospital environment. EVOLUTION MEDICINE AND PUBLIC HEALTH 2016; 2016:219-26. [PMID: 27412864 PMCID: PMC4972940 DOI: 10.1093/emph/eow021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 06/29/2016] [Indexed: 01/09/2023]
Abstract
Background and objectives: Widespread use of antibiotics has resulted in selection pressure on genes that make bacteria non-responsive to antibiotics. These antibiotic-resistant bacteria are currently a major threat to global health. There are various possibilities for the transfer of antibiotic resistance genes. It has been argued that animal vectors such as Rattus norvegicus (R. norvegicus) living in hospital sewage systems are ideal for carrying pathogens responsible for fatal diseases in humans. Methodology: Using a metagenomic sequencing approach, we investigated faecal samples of R. norvegicus from three major cities for the presence of antibiotic resistance genes. Results: We show that despite the shared resistome within samples from the same geographic locations, samples from hospital area carry significantly abundant vancomycin resistance genes. Conclusions and implications: The observed pattern is consistent with a selection for vancomycin genes in the R. norvegicus microbiome, potentially driven by the outflow of antibiotics and antibiotic-resistant bacteria into the wastewater systems. Carriage of vancomycin resistance may suggest that R. norvegicus is acting as a reservoir for possible transmission to the human population.
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Affiliation(s)
- Thomas Arn Hansen
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, DK-1350, Denmark
| | - Tejal Joshi
- Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Kemitorvet, 2800, Kgs, Lyngby, Denmark
| | | | | | - Klaus Harms
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, DK-1350, Denmark
| | - Sarah Mollerup
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, DK-1350, Denmark
| | - Eske Willerslev
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, DK-1350, Denmark
| | - Kurt Fuursted
- Department of Microbiology & Infection Control, Statens Serum Institut
| | - Lars Peter Nielsen
- Department of Autoimmunology and Biomarkers, Statens Serum Institut, Copenhagen S, DK-2300, Denmark
| | - Anders Johannes Hansen
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, DK-1350, Denmark;
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Mizrahi A, Collignon A, Péchiné S. Passive and active immunization strategies against Clostridium difficile infections: State of the art. Anaerobe 2014; 30:210-9. [DOI: 10.1016/j.anaerobe.2014.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 07/07/2014] [Accepted: 07/18/2014] [Indexed: 02/04/2023]
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Bellanger X, Payot S, Leblond-Bourget N, Guédon G. Conjugative and mobilizable genomic islands in bacteria: evolution and diversity. FEMS Microbiol Rev 2014; 38:720-60. [DOI: 10.1111/1574-6976.12058] [Citation(s) in RCA: 223] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 11/15/2013] [Accepted: 12/19/2013] [Indexed: 11/28/2022] Open
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Lam MMC, Seemann T, Tobias NJ, Chen H, Haring V, Moore RJ, Ballard S, Grayson LM, Johnson PDR, Howden BP, Stinear TP. Comparative analysis of the complete genome of an epidemic hospital sequence type 203 clone of vancomycin-resistant Enterococcus faecium. BMC Genomics 2013; 14:595. [PMID: 24004955 PMCID: PMC3846456 DOI: 10.1186/1471-2164-14-595] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 08/28/2013] [Indexed: 11/10/2022] Open
Abstract
Background In this report we have explored the genomic and microbiological basis for a sustained increase in bloodstream infections at a major Australian hospital caused by Enterococcus faecium multi-locus sequence type (ST) 203, an outbreak strain that has largely replaced a predecessor ST17 sequence type. Results To establish a ST203 reference sequence we fully assembled and annotated the genome of Aus0085, a 2009 vancomycin-resistant Enterococcus faecium (VREfm) bloodstream isolate, and the first example of a completed ST203 genome. Aus0085 has a 3.2 Mb genome, comprising a 2.9 Mb circular chromosome and six circular plasmids (2 kb–130 kb). Twelve percent of the 3222 coding sequences (CDS) in Aus0085 are not present in ST17 E. faecium Aus0004 and ST18 E. faecium TX16. Extending this comparison to an additional 12 ST17 and 14 ST203 E. faecium hospital isolate genomes revealed only six genomic regions spanning 41 kb that were present in all ST203 and absent from all ST17 genomes. The 40 CDS have predicted functions that include ion transport, riboflavin metabolism and two phosphotransferase systems. Comparison of the vancomycin resistance-conferring Tn1549 transposon between Aus0004 and Aus0085 revealed differences in transposon length and insertion site, and van locus sequence variation that correlated with a higher vancomycin MIC in Aus0085. Additional phenotype comparisons between ST17 and ST203 isolates showed that while there were no differences in biofilm-formation and killing of Galleria mellonella, ST203 isolates grew significantly faster and out-competed ST17 isolates in growth assays. Conclusions Here we have fully assembled and annotated the first ST203 genome, and then characterized the genomic differences between ST17 and ST203 E. faecium. We also show that ST203 E. faecium are faster growing and can out-compete ST17 E. faecium. While a causal genetic basis for these phenotype differences is not provided here, this study revealed conserved genetic differences between the two clones, differences that can now be tested to explain the molecular basis for the success and emergence of ST203 E. faecium.
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Affiliation(s)
- Margaret M C Lam
- Department of Microbiology and Immunology, University of Melbourne, Parkville 3010, Victoria, Australia.
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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: 116] [Impact Index Per Article: 10.5] [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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21
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Abstract
Enterococci have the potential for resistance to virtually all clinically useful antibiotics. Their emergence as important nosocomial pathogens has coincided with increased expression of antimicrobial resistance by members of the genus. The mechanisms underlying antibiotic resistance in enterococci may be intrinsic to the species or acquired through mutation of intrinsic genes or horizontal exchange of genetic material encoding resistance determinants. This paper reviews the antibiotic resistance mechanisms in Enterococcus faecium and Enterococcus faecalis and discusses treatment options.
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Affiliation(s)
- Brian L Hollenbeck
- Department of Medicine, Lifespan/Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI, USA
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Bapteste E, Bouchard F, Burian RM. Philosophy and evolution: minding the gap between evolutionary patterns and tree-like patterns. Methods Mol Biol 2012; 856:81-110. [PMID: 22399456 DOI: 10.1007/978-1-61779-585-5_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Ever since Darwin, the familiar genealogical pattern known as the Tree of Life (TOL) has been prominent in evolutionary thinking and has dominated not only systematics, but also the analysis of the units of evolution. However, recent findings indicate that the evolution of DNA, especially in prokaryotes and such DNA vehicles as viruses and plasmids, does not follow a unique tree-like pattern. Because evolutionary patterns track a greater range of processes than those captured in genealogies, genealogical patterns are in fact only a subset of a broader set of evolutionary patterns. This fact suggests that evolutionists who focus exclusively on genealogical patterns are blocked from providing a significant range of genuine evolutionary explanations. Consequently, we highlight challenges to tree-based approaches, and point the way toward more appropriate methods to study evolution (although we do not present them in technical detail). We argue that there is significant benefit in adopting wider range of models, evolutionary representations, and evolutionary explanations, based on an analysis of the full range of evolutionary processes. We introduce an ecosystem orientation into evolutionary thinking that highlights the importance of "type 1 coalitions" (functionally related units with genetic exchanges, aka "friends with genetic benefits"), "type 2 coalitions" (functionally related units without genetic exchanges), "communal interactions," and "emergent evolutionary properties." On this basis, we seek to promote the study of (especially prokaryotic) evolution with dynamic evolutionary networks, which are less constrained than the TOL, and to provide new ways to analyze an expanded range of evolutionary units (genetic modules, recombined genes, plasmids, phages and prokaryotic genomes, pangenomes, microbial communities) and evolutionary processes. Finally, we discuss some of the conceptual and practical questions raised by such network-based representation.
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Green fluorescent protein-labeled monitoring tool to quantify conjugative plasmid transfer between Gram-positive and Gram-negative bacteria. Appl Environ Microbiol 2011; 78:895-9. [PMID: 22138997 DOI: 10.1128/aem.05578-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
On the basis of pIP501, a green fluorescent protein (GFP)-tagged monitoring tool was constructed for quantifying plasmid mobilization among Gram-positive bacteria and between Gram-positive Enterococcus faecalis and Gram-negative Escherichia coli. Furthermore, retromobilization of the GFP-tagged monitoring tool was shown from E. faecalis OG1X into the clinical isolate E. faecalis T9.
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Werner G, Serr A, Schütt S, Schneider C, Klare I, Witte W, Wendt C. Comparison of direct cultivation on a selective solid medium, polymerase chain reaction from an enrichment broth, and the BD GeneOhm™ VanR Assay for identification of vancomycin-resistant enterococci in screening specimens. Diagn Microbiol Infect Dis 2011; 70:512-21. [DOI: 10.1016/j.diagmicrobio.2011.04.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/21/2011] [Accepted: 04/06/2011] [Indexed: 11/15/2022]
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25
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Clostridium clostridioforme and Atopobium minutum clinical isolates with vanB-type resistance in France. J Clin Microbiol 2011; 49:3436-8. [PMID: 21775552 DOI: 10.1128/jcm.00308-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acquired vancomycin resistance in Gram-positive anaerobes has been reported only in Australia and Canada from rare vanB-positive stool samples in the absence of vancomycin-resistant enterococci (VRE). We report the emergence of VanB-type resistance in Clostridium clostridioforme and Atopobium minutum involved in human infections in France.
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Roberts AP, Mullany P. Tn916-like genetic elements: a diverse group of modular mobile elements conferring antibiotic resistance. FEMS Microbiol Rev 2011; 35:856-71. [PMID: 21658082 DOI: 10.1111/j.1574-6976.2011.00283.x] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Antibiotic-resistant Gram-positive bacteria are responsible for morbidity and mortality in healthcare environments. Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus and Streptococcus pneumoniae can all exhibit clinically relevant multidrug resistance phenotypes due to acquired resistance genes on mobile genetic elements. It is possible that clinically relevant multidrug-resistant Clostridium difficile strains will appear in the future, as the organism is adept at acquiring mobile genetic elements (plasmids and transposons). Conjugative transposons of the Tn916/Tn1545 family, which carry major antibiotic resistance determinants, are transmissible between these different bacteria by a conjugative mechanism during which the elements are excised by a staggered cut from donor cells, converted to a circular form, transferred by cell-cell contact and inserted into recipient cells by a site-specific recombinase. The ability of these conjugative transposons to acquire additional, clinically relevant antibiotic resistance genes importantly contributes to the emergence of multidrug resistance.
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Affiliation(s)
- Adam P Roberts
- Department of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK
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Jasni AS, Mullany P, Hussain H, Roberts AP. Demonstration of conjugative transposon (Tn5397)-mediated horizontal gene transfer between Clostridium difficile and Enterococcus faecalis. Antimicrob Agents Chemother 2010; 54:4924-6. [PMID: 20713671 PMCID: PMC2976158 DOI: 10.1128/aac.00496-10] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/07/2010] [Accepted: 08/09/2010] [Indexed: 01/05/2023] Open
Abstract
Antibiotic-resistant Enterococcus faecalis and Clostridium difficile are responsible for nosocomial infections in humans, in which they inhabit the same niche. Here, we demonstrate transfer of the conjugative transposon Tn5397 from C. difficile 630 to E. faecalis JH2-2, the first reported gene transfer between these two bacteria. Furthermore, transfer from the E. faecalis EF20A transconjugant to the epidemic ribotype 027 C. difficile strain R20291 was also demonstrated. Tn5397 was shown to use a single specific target site in E. faecalis; it also has specific target sites in C. difficile. These experiments highlight the importance of continual monitoring for emerging resistances in these bacteria.
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Affiliation(s)
- Azmiza S. Jasni
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, United Kingdom
| | - Peter Mullany
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, United Kingdom
| | - Haitham Hussain
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, United Kingdom
| | - Adam P. Roberts
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, United Kingdom
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