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Garrido V, Arrieta-Gisasola A, Migura-García L, Laorden L, Grilló MJ. Multidrug resistance in Salmonella isolates of swine origin: mobile genetic elements and plasmids associated with cephalosporin resistance with potential transmission to humans. Appl Environ Microbiol 2024; 90:e0026424. [PMID: 38695519 PMCID: PMC11107176 DOI: 10.1128/aem.00264-24] [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: 02/13/2024] [Accepted: 04/03/2024] [Indexed: 05/22/2024] Open
Abstract
The emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context requiring continuous surveillance. Resistance to ciprofloxacin and cephalosporins is of particular concern. Since pigs are a relevant source of foodborne Salmonella for human beings, we studied transmissible AMR genes and MGE in a collection of 83 strains showing 9 different serovars and 15 patterns of multidrug resistant (MDR) previously isolated from pigs raised in the conventional breeding system of Northern Spain. All isolates were susceptible to ciprofloxacin and three isolates carried blaCMY-2 or blaCTX-M-9 genes responsible for cefotaxime resistance. Filter mating experiments showed that the two plasmids carrying blaCTX-M-9 were conjugative while that carrying blaCMY-2 was self-transmissible by transformation. Whole-genome sequencing and comparative analyses were performed on the isolates and plasmids. The IncC plasmid pSB109, carrying blaCMY-2, was similar to one found in S. Reading from cattle, indicating potential horizontal transfer between serovars and animal sources. The IncHI2 plasmids pSH102 in S. Heidelberg and pSTM45 in S. Typhimurium ST34, carrying blaCTX-M-9, shared similar backbones and two novel "complex class 1 integrons" containing different AMR and heavy metal genes. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.IMPORTANCEThe emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context. Since pigs are a relevant source of foodborne Salmonella for humans, in this study, we investigate different aspects of AMR in a collection of 83 Salmonella showing nine different serovars and 15 patterns of multidrug resistant (MDR) isolated from pigs raised in the conventional breeding system. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.
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Affiliation(s)
- V. Garrido
- Instituto de Agrobiotecnología (IdAB; CSIC-Gobierno de Navarra), Mutilva, Navarra, Spain
| | - A. Arrieta-Gisasola
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, MikroIker Research Group, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain
| | - L. Migura-García
- Joint Research Unit IRTA-UAB in Animal Health, Animal Health Research Centre (CReSA), Autonomous University of Barcelona (UAB), Catalonia, Spain
- Institute of Agrifood Research and Technology (IRTA), Animal Health Program (CReSA), WOAH Collaborating Centre for the Research and Control of Emerging and Re-Emerging Swine Diseases in Europe, Autonomous University of Barcelona (UAB), Barcelona, Catalonia, Spain
| | - L. Laorden
- Department of Immunology, Microbiology and Parasitology, Faculty of Pharmacy, MikroIker Research Group, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain
| | - M. J. Grilló
- Instituto de Agrobiotecnología (IdAB; CSIC-Gobierno de Navarra), Mutilva, Navarra, Spain
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Murányi G, Szabó M, Acsai K, Kiss J. Two birds with one stone: SGI1 can stabilize itself and expel the IncC helper by hijacking the plasmid parABS system. Nucleic Acids Res 2024; 52:2498-2518. [PMID: 38300764 PMCID: PMC10954446 DOI: 10.1093/nar/gkae050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 02/03/2024] Open
Abstract
The SGI1 family integrative mobilizable elements, which are efficient agents in distribution of multidrug resistance in Gammaproteobacteria, have a complex, parasitic relationship with their IncC conjugative helper plasmids. Besides exploiting the transfer apparatus, SGI1 also hijacks IncC plasmid control mechanisms to time its own excision, replication and expression of self-encoded T4SS components, which provides advantages for SGI1 over its helpers in conjugal transfer and stable maintenance. Furthermore, SGI1 destabilizes its helpers in an unknown, replication-dependent way when they are concomitantly present in the same host. Here we report how SGI1 exploits the helper plasmid partitioning system to displace the plasmid and simultaneously increase its own stability. We show that SGI1 carries two copies of sequences mimicking the parS sites of IncC plasmids. These parS-like elements bind the ParB protein encoded by the plasmid and increase SGI1 stability by utilizing the parABS system of the plasmid for its own partitioning, through which SGI1 also destabilizes the helper plasmid. Furthermore, SGI1 expresses a small protein, Sci, which significantly strengthens this plasmid-destabilizing effect, as well as SGI1 maintenance. The plasmid-induced replication of SGI1 results in an increased copy-number of parS-like sequences and Sci expression leading to strong incompatibility with the helper plasmid.
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Affiliation(s)
- Gábor Murányi
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
| | - Mónika Szabó
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Gödöllő, H2100 Hungary
| | - Károly Acsai
- Ceva Animal Health, Ceva-Phylaxia, Budapest, H1107 Hungary
| | - János Kiss
- Department of Microbiology and Applied Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, H2100 Hungary
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Gödöllő, H2100 Hungary
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3
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Ambrose SJ, Hall RM. Effect of the S008-sgaCD operon on IncC plasmid stability in the presence of SGI1-K or absence of an SGI1 variant. Plasmid 2023; 127:102698. [PMID: 37516393 DOI: 10.1016/j.plasmid.2023.102698] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 07/24/2023] [Accepted: 07/24/2023] [Indexed: 07/31/2023]
Abstract
An IncC or IncA plasmid is needed to enable transfer of SGI1 type integrative mobilisable elements but an IncC plasmid does not stably co-exist with SGI1. However, the plasmid is stably maintained with SGI1-K, a natural SGI1 deletion variant that lacks the sgaDC genes (S007 and S006) and the upstream open reading frame (S008) found in the SGI1 backbone. Here, the effect of the sgaDC genes and S008 on the stability of an IncC plasmid in an Escherichia coli strain with or without SGI1-K was examined. Co-transcription of the S008 open reading frame with the downstream sgaDC genes was established. When a strain containing SGI1-K complemented with a pK18 plasmid that included S008-sgaDC or sgaDC expressed from the constitutive pUC promoter was grown without antibiotic selection, the resident IncC plasmid was rapidly lost but loss was slower when S008 was present. In contrast, SGI1-K and the S008-sgaDC or sgaDC plasmid were quite stably maintained for >100 generations. However, the high copy number plasmids carrying the SGI1-derived S008-sgaDC or sgaDC genes constitutively expressed could not be introduced into an E. coli strain carrying the IncC plasmid but without SGI1-K. Using equivalent plasmids with S008-sgaDC or sgaDC genes controlled by an arabinose-inducible promoter, under inducing conditions the IncC plasmid was stable but the plasmid containing the SGI1-derived genes was rapidly lost. This unexpected observation indicates that there are multiple interactions between the IncC plasmid and SGI1 in which the transcriptional activator genes sgaDC play a role. These interactions will require further investigation.
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Affiliation(s)
- Stephanie J Ambrose
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
| | - Ruth M Hall
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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Pons MC, Praud K, Da Re S, Cloeckaert A, Doublet B. Conjugative IncC Plasmid Entry Triggers the SOS Response and Promotes Effective Transfer of the Integrative Antibiotic Resistance Element SGI1. Microbiol Spectr 2023; 11:e0220122. [PMID: 36472437 PMCID: PMC9927553 DOI: 10.1128/spectrum.02201-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022] Open
Abstract
The broad-host-range IncC plasmid family and the integrative mobilizable Salmonella genomic island 1 (SGI1) and its derivatives enable the spread of medically important antibiotic resistance genes among Gram-negative pathogens. Although several aspects of the complex functional interactions between IncC plasmids and SGI1 have been recently deciphered regarding their conjugative transfer and incompatibility, the biological signal resulting in the hijacking of the conjugative plasmid by the integrative mobilizable element remains unknown. Here, we demonstrate that the conjugative entry of IncC/IncA plasmids is detected at an early stage by SGI1 through the transient activation of the SOS response, which induces the expression of the SGI1 master activators SgaDC, shown to play a crucial role in the complex biology between SGI1 and IncC plasmids. Besides, we developed an original tripartite conjugation approach to directly monitor SGI1 mobilization in a time-dependent manner following conjugative entry of IncC plasmids. Finally, we propose an updated biological model of the conjugative mobilization of the chromosomal resistance element SGI1 by IncC plasmids. IMPORTANCE Antimicrobial resistance has become a major public health issue, particularly with the increase of multidrug resistance (MDR) in both animal and human pathogenic bacteria and with the emergence of resistance to medically important antibiotics. The spread between bacteria of successful mobile genetic elements, such as conjugative plasmids and integrative elements conferring multidrug resistance, is the main driving force in the dissemination of acquired antibiotic resistances among Gram-negative bacteria. Broad-host-range IncC plasmids and their integrative mobilizable SGI1 counterparts contribute to the spread of critically important resistance genes (e.g., extended-spectrum β-lactamases [ESBLs] and carbapenemases). A better knowledge of the complex biology of these broad-host-range mobile elements will help us to understand the dissemination of antimicrobial resistance genes that occurred across Gammaproteobacteria borders.
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Affiliation(s)
| | - Karine Praud
- INRAE, Université de Tours, ISP, Nouzilly, France
| | - Sandra Da Re
- INSERM, Université de Limoges, CHU de Limoges, RESINFIT, Limoges, France
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5
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Ambrose SJ, Hall RM. Can SGI1 family integrative mobilizable elements overcome entry exclusion exerted by IncA and IncC plasmids on IncC plasmids? Plasmid 2022; 123-124:102654. [DOI: 10.1016/j.plasmid.2022.102654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/28/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022]
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Algarni S, Ricke SC, Foley SL, Han J. The Dynamics of the Antimicrobial Resistance Mobilome of Salmonella enterica and Related Enteric Bacteria. Front Microbiol 2022; 13:859854. [PMID: 35432284 PMCID: PMC9008345 DOI: 10.3389/fmicb.2022.859854] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/07/2022] [Indexed: 12/31/2022] Open
Abstract
The foodborne pathogen Salmonella enterica is considered a global public health risk. Salmonella enterica isolates can develop resistance to several antimicrobial drugs due to the rapid spread of antimicrobial resistance (AMR) genes, thus increasing the impact on hospitalization and treatment costs, as well as the healthcare system. Mobile genetic elements (MGEs) play key roles in the dissemination of AMR genes in S. enterica isolates. Multiple phenotypic and molecular techniques have been utilized to better understand the biology and epidemiology of plasmids including DNA sequence analyses, whole genome sequencing (WGS), incompatibility typing, and conjugation studies of plasmids from S. enterica and related species. Focusing on the dynamics of AMR genes is critical for identification and verification of emerging multidrug resistance. The aim of this review is to highlight the updated knowledge of AMR genes in the mobilome of Salmonella and related enteric bacteria. The mobilome is a term defined as all MGEs, including plasmids, transposons, insertion sequences (ISs), gene cassettes, integrons, and resistance islands, that contribute to the potential spread of genes in an organism, including S. enterica isolates and related species, which are the focus of this review.
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Affiliation(s)
- Suad Algarni
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- Cellular and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, AR, United States
| | - Steven C. Ricke
- Meat Science and Animal Biologics Discovery Program, Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI, United States
| | - Steven L. Foley
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- Cellular and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, AR, United States
| | - Jing Han
- Division of Microbiology, FDA National Center for Toxicological Research, Jefferson, AR, United States
- *Correspondence: Jing Han,
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Nagy I, Szabó M, Hegyi A, Kiss J. Salmonella Genomic Island 1 requires a self-encoded small RNA for mobilization. Mol Microbiol 2021; 116:1533-1551. [PMID: 34784078 PMCID: PMC9299015 DOI: 10.1111/mmi.14846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/08/2021] [Accepted: 11/13/2021] [Indexed: 11/29/2022]
Abstract
The SGI1-family elements that are specifically mobilized by the IncA- and IncC-family plasmids are important vehicles of antibiotic resistance among enteric bacteria. Although SGI1 exploits many plasmid-derived conjugation and regulatory functions, the basic mobilization module of the island is unrelated to that of IncC plasmids. This module contains the oriT and encodes the mobilization proteins MpsA and MpsB, which belong to the tyrosine recombinases and not to relaxases. Here we report an additional, essential transfer factor of SGI1. This is a small RNA deriving from the 3'-end of a primary RNA that can also serve as mRNA of ORF S022. The functional domain of this sRNA named sgm-sRNA is encoded between the mpsA gene and the oriT of SGI1. Terminator-like sequence near the promoter of the primary transcript possibly has a regulatory function in controlling the amount of full-length primary RNA, which is converted to the active sgm-sRNA through consecutive maturation steps influenced by the 5'-end of the primary RNA. The mobilization module of SGI1 seems unique due to its atypical relaxase and the newly identified sgm-sRNA, which is required for the horizontal transfer of the island but appears to act differently from classical regulatory sRNAs.
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Affiliation(s)
- István Nagy
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
| | - Mónika Szabó
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
| | - Anna Hegyi
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
| | - János Kiss
- Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
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8
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Durand R, Deschênes F, Burrus V. Genomic islands targeting dusA in Vibrio species are distantly related to Salmonella Genomic Island 1 and mobilizable by IncC conjugative plasmids. PLoS Genet 2021; 17:e1009669. [PMID: 34415925 PMCID: PMC8409611 DOI: 10.1371/journal.pgen.1009669] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/01/2021] [Accepted: 08/09/2021] [Indexed: 11/18/2022] Open
Abstract
Salmonella Genomic Island 1 (SGI1) and its variants are significant contributors to the spread of antibiotic resistance among Gammaproteobacteria. All known SGI1 variants integrate at the 3’ end of trmE, a gene coding for a tRNA modification enzyme. SGI1 variants are mobilized specifically by conjugative plasmids of the incompatibility groups A and C (IncA and IncC). Using a comparative genomics approach based on genes conserved among members of the SGI1 group, we identified diverse integrative elements distantly related to SGI1 in several species of Vibrio, Aeromonas, Salmonella, Pokkaliibacter, and Escherichia. Unlike SGI1, these elements target two alternative chromosomal loci, the 5’ end of dusA and the 3’ end of yicC. Although they share many features with SGI1, they lack antibiotic resistance genes and carry alternative integration/excision modules. Functional characterization of IMEVchUSA3, a dusA-specific integrative element, revealed promoters that respond to AcaCD, the master activator of IncC plasmid transfer genes. Quantitative PCR and mating assays confirmed that IMEVchUSA3 excises from the chromosome and is mobilized by an IncC helper plasmid from Vibrio cholerae to Escherichia coli. IMEVchUSA3 encodes the AcaC homolog SgaC that associates with AcaD to form a hybrid activator complex AcaD/SgaC essential for its excision and mobilization. We identified the dusA-specific recombination directionality factor RdfN required for the integrase-mediated excision of dusA-specific elements from the chromosome. Like xis in SGI1, rdfN is under the control of an AcaCD-responsive promoter. Although the integration of IMEVchUSA3 disrupts dusA, it provides a new promoter sequence and restores the reading frame of dusA for proper expression of the tRNA-dihydrouridine synthase A. Phylogenetic analysis of the conserved proteins encoded by SGI1-like elements targeting dusA, yicC, and trmE gives a fresh perspective on the possible origin of SGI1 and its variants. We identified integrative elements distantly related to Salmonella Genomic Island 1 (SGI1), a key vector of antibiotic resistance genes in Gammaproteobacteria. SGI1 and its variants reside at the 3’ end of trmE, share a large, highly conserved core of genes, and carry a complex integron that confers multidrug resistance phenotypes to their hosts. Unlike members of the SGI1 group, these novel genomic islands target the 5’ end dusA or the 3’ end of yicC, lack multidrug resistance genes, and seem much more diverse. We showed here that, like SGI1, these elements are mobilized by conjugative plasmids of the IncC group. Based on comparative genomics and functional analyses, we propose a hypothetical model of the evolution of SGI1 and its siblings from the progenitor of IncA and IncC conjugative plasmids via an intermediate dusA-specific integrative element through gene losses and gain of alternative integration/excision modules.
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Affiliation(s)
- Romain Durand
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Florence Deschênes
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Vincent Burrus
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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9
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Durand R, Huguet KT, Rivard N, Carraro N, Rodrigue S, Burrus V. Crucial role of Salmonella genomic island 1 master activator in the parasitism of IncC plasmids. Nucleic Acids Res 2021; 49:7807-7824. [PMID: 33834206 PMCID: PMC8373056 DOI: 10.1093/nar/gkab204] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 03/09/2021] [Accepted: 03/15/2021] [Indexed: 12/26/2022] Open
Abstract
IncC conjugative plasmids and the multiple variants of Salmonella Genomic Island 1 (SGI1) are two functionally interacting families of mobile genetic elements commonly associated with multidrug resistance in the Gammaproteobacteria. SGI1 and its siblings are specifically mobilised in trans by IncC conjugative plasmids. Conjugative transfer of IncC plasmids is activated by the plasmid-encoded master activator AcaCD. SGI1 carries five AcaCD-responsive promoters that drive the expression of genes involved in its excision, replication, and mobilisation. SGI1 encodes an AcaCD homologue, the transcriptional activator complex SgaCD (also known as FlhDCSGI1) that seems to recognise and activate the same SGI1 promoters. Here, we investigated the relevance of SgaCD in SGI1's lifecycle. Mating assays revealed the requirement for SgaCD and its IncC-encoded counterpart AcaCD in the mobilisation of SGI1. An integrative approach combining ChIP-exo, Cappable-seq, and RNA-seq confirmed that SgaCD activates each of the 18 AcaCD-responsive promoters driving the expression of the plasmid transfer functions. A comprehensive analysis of the activity of the complete set of AcaCD-responsive promoters of SGI1 and the helper IncC plasmid was performed through reporter assays. qPCR and flow cytometry assays revealed that SgaCD is essential to elicit the excision and replication of SGI1 and destabilise the helper IncC plasmid.
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Affiliation(s)
- Romain Durand
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Kévin T Huguet
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Nicolas Rivard
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Nicolas Carraro
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Sébastien Rodrigue
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Vincent Burrus
- Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
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Neil K, Allard N, Rodrigue S. Molecular Mechanisms Influencing Bacterial Conjugation in the Intestinal Microbiota. Front Microbiol 2021; 12:673260. [PMID: 34149661 PMCID: PMC8213034 DOI: 10.3389/fmicb.2021.673260] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 05/10/2021] [Indexed: 12/26/2022] Open
Abstract
Bacterial conjugation is a widespread and particularly efficient strategy to horizontally disseminate genes in microbial populations. With a rich and dense population of microorganisms, the intestinal microbiota is often considered a fertile environment for conjugative transfer and a major reservoir of antibiotic resistance genes. In this mini-review, we summarize recent findings suggesting that few conjugative plasmid families present in Enterobacteriaceae transfer at high rates in the gut microbiota. We discuss the importance of mating pair stabilization as well as additional factors influencing DNA transfer efficiency and conjugative host range in this environment. Finally, we examine the potential repurposing of bacterial conjugation for microbiome editing.
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Affiliation(s)
| | | | - Sébastien Rodrigue
- Départment de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
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de Curraize C, Siebor E, Neuwirth C. Genomic islands related to Salmonella genomic island 1; integrative mobilisable elements in trmE mobilised in trans by A/C plasmids. Plasmid 2021; 114:102565. [PMID: 33582118 DOI: 10.1016/j.plasmid.2021.102565] [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: 10/19/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/01/2022]
Abstract
Salmonella genomic island 1 (SGI1), an integrative mobilisable element (IME), was first reported 20 years ago, in the multidrug resistant Salmonella Typhimurium DT104 clone. Since this first report, many variants and relatives have been found in Salmonella enterica and Proteus mirabilis. Thanks to whole genome sequencing, more and more complete sequences of SGI1-related elements (SGI1-REs) have been reported in these last few years among Gammaproteobacteria. Here, the genetic organisation and main features common to SGI1-REs are summarised to help to classify them. Their integrases belong to the tyrosine-recombinase family and target the 3'-end of the trmE gene. They share the same genetic organisation (integrase and excisionase genes, replicase module, SgaCD-like transcriptional activator genes, traN, traG, mpsB/mpsA genes) and they harbour AcaCD binding sites promoting their excision, replication and mobilisation in presence of A/C plasmid. SGI1-REs are mosaic structures suggesting that recombination events occurred between them. Most of them harbour a multiple antibiotic resistance (MAR) region and the plasticity of their MAR region show that SGI1-REs play a key role in antibiotic resistance and might help multiple antibiotic resistant bacteria to adapt to their environment. This might explain the emergence of clones with SGI1-REs.
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Affiliation(s)
- Claire de Curraize
- Bacteriology Department, University Hospital Dijon, PBHU, BP 37013, 21070 Dijon Cedex, France; UMR 6249, Chrono-Environnement, PBHU, BP 37013, 21070 Dijon Cedex, France.
| | - Eliane Siebor
- Bacteriology Department, University Hospital Dijon, PBHU, BP 37013, 21070 Dijon Cedex, France; UMR 6249, Chrono-Environnement, PBHU, BP 37013, 21070 Dijon Cedex, France.
| | - Catherine Neuwirth
- Bacteriology Department, University Hospital Dijon, PBHU, BP 37013, 21070 Dijon Cedex, France; UMR 6249, Chrono-Environnement, PBHU, BP 37013, 21070 Dijon Cedex, France.
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12
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Szabó M, Murányi G, Kiss J. IncC helper dependent plasmid-like replication of Salmonella Genomic Island 1. Nucleic Acids Res 2021; 49:832-846. [PMID: 33406256 PMCID: PMC7826253 DOI: 10.1093/nar/gkaa1257] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/24/2020] [Accepted: 12/17/2020] [Indexed: 12/16/2022] Open
Abstract
The Salmonella genomic island 1 (SGI1) and its variants are mobilized by IncA and IncC conjugative plasmids. SGI1-family elements and their helper plasmids are effective transporters of multidrug resistance determinants. SGI1 exploits the transfer apparatus of the helper plasmid and hijacks its activator complex, AcaCD, to trigger the expression of several SGI1 genes. In this way, SGI1 times its excision from the chromosome to the helper entry and expresses mating pore components that enhance SGI1 transfer. The SGI1-encoded T4SS components and the FlhDC-family activator proved to be interchangeable with their IncC-encoded homologs, indicating multiple interactions between SGI1 and its helpers. As a new aspect of this crosstalk, we report here the helper-induced replication of SGI1, which requires both activators, AcaCD and FlhDCSGI1, and significantly increases the stability of SGI1 when coexists with the helper plasmid. We have identified the oriVSGI1 and shown that S004-repA operon encodes for a translationally coupled leader protein and an IncN2/N3-related RepA that are expressed under the control of the AcaCD-responsive promoter PS004. This replicon transiently maintains SGI1 as a 4–8-copy plasmid, not only stabilizing the island but also contributing to the fast displacement of the helper plasmid.
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Affiliation(s)
- Mónika Szabó
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - Gábor Murányi
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - János Kiss
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
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Libante V, Sarica N, Mohamad Ali A, Gapp C, Oussalah A, Guédon G, Leblond-Bourget N, Payot S. Mobilization of IMEs Integrated in the oriT of ICEs Involves Their Own Relaxase Belonging to the Rep-Trans Family of Proteins. Genes (Basel) 2020; 11:genes11091004. [PMID: 32859088 PMCID: PMC7563843 DOI: 10.3390/genes11091004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 01/27/2023] Open
Abstract
Integrative mobilizable elements (IMEs) are widespread but very poorly studied integrated elements that can excise and hijack the transfer apparatus of co-resident conjugative elements to promote their own spreading. Sixty-four putative IMEs, harboring closely related mobilization and recombination modules, were found in 14 Streptococcus species and in Staphylococcus aureus. Fifty-three are integrated into the origin of transfer (oriT) of a host integrative conjugative element (ICE), encoding a MobT relaxase and belonging to three distant families: ICESt3, Tn916, and ICE6013. The others are integrated into an unrelated IME or in chromosomal sites. After labeling by an antibiotic resistance gene, the conjugative transfer of one of these IMEs (named IME_oriTs) and its host ICE was measured. Although the IME is integrated in an ICE, it does not transfer as a part of the host ICE (no cis-mobilization). The IME excises and transfers separately from the ICE (without impacting its transfer rate) using its own relaxase, distantly related to all known MobT relaxases, and integrates in the oriT of the ICE after transfer. Overall, IME_oriTs use MobT-encoding ICEs both as hosts and as helpers for conjugative transfer. As half of them carry lsa(C), they actively participate in the dissemination of lincosamide–streptogramin A–pleuromutilin resistance among Firmicutes.
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Huguet KT, Rivard N, Garneau D, Palanee J, Burrus V. Replication of the Salmonella Genomic Island 1 (SGI1) triggered by helper IncC conjugative plasmids promotes incompatibility and plasmid loss. PLoS Genet 2020; 16:e1008965. [PMID: 32760058 PMCID: PMC7433901 DOI: 10.1371/journal.pgen.1008965] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/18/2020] [Accepted: 06/30/2020] [Indexed: 12/27/2022] Open
Abstract
The mobilizable resistance island Salmonella genomic island 1 (SGI1) is specifically mobilized by IncA and IncC conjugative plasmids. SGI1, its variants and IncC plasmids propagate multidrug resistance in pathogenic enterobacteria such as Salmonella enterica serovars and Proteus mirabilis. SGI1 modifies and uses the conjugation apparatus encoded by the helper IncC plasmid, thus enhancing its own propagation. Remarkably, although SGI1 needs a coresident IncC plasmid to excise from the chromosome and transfer to a new host, these elements have been reported to be incompatible. Here, the stability of SGI1 and its helper IncC plasmid, each expressing a different fluorescent reporter protein, was monitored using fluorescence-activated cell sorting (FACS). Without selective pressure, 95% of the cells segregated into two subpopulations containing either SGI1 or the helper plasmid. Furthermore, FACS analysis revealed a high level of SGI1-specific fluorescence in IncC+ cells, suggesting that SGI1 undergoes active replication in the presence of the helper plasmid. SGI1 replication was confirmed by quantitative PCR assays, and extraction and restriction of its plasmid form. Deletion of genes involved in SGI1 excision from the chromosome allowed a stable coexistence of SGI1 with its helper plasmid without selective pressure. In addition, deletion of S003 (rep) or of a downstream putative iteron-based origin of replication, while allowing SGI1 excision, abolished its replication, alleviated the incompatibility with the helper plasmid and enabled its cotransfer to a new host. Like SGI1 excision functions, rep expression was found to be controlled by AcaCD, the master activator of IncC plasmid transfer. Transient SGI1 replication seems to be a key feature of the life cycle of this family of genomic islands. Sequence database analysis revealed that SGI1 variants encode either a replication initiator protein with a RepA_C domain, or an alternative replication protein with N-terminal replicase and primase C terminal 1 domains. The Salmonella genomic island 1 (SGI1) and its variants propagate multidrug resistance in several species of human and animal pathogens with the help of IncA and IncC conjugative plasmids that are absolutely required for SGI1 dissemination. These helper plasmids are known to trigger the excision of SGI1 from the chromosome. Here, we found that IncC plasmids also trigger the replication of the excised, circular form of SGI1 by enabling the expression of an SGI1-borne replication initiator gene. In return, high-copy replication of SGI1 interferes with the persistence of the IncC plasmid and prevents its cotransfer into a recipient cell, thereby allowing integration and stabilization of SGI1 into the chromosome of the new host. This finding is important to better understand the complex interactions between SGI1-like elements and their helper plasmids that lead to widespread and highly efficient propagation of multidrug resistance genes to a broad range of human and animal pathogens.
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Affiliation(s)
- Kévin T. Huguet
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Nicolas Rivard
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Daniel Garneau
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Jason Palanee
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Vincent Burrus
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail:
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15
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Siebor E, Neuwirth C. New insights regarding Acinetobacter genomic island-related elements. Int J Antimicrob Agents 2020; 56:106117. [PMID: 32745526 DOI: 10.1016/j.ijantimicag.2020.106117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 11/30/2022]
Abstract
The objective of this study was to mobilise the Acinetobacter genomic island 1-A (AGI1-A) from Enterobacter hormaechei EclCSP2185 (E. cloacae complex) and to search for the distribution and structure of AGI1-related elements in the NCBI database. AGI1-A was transferred to Escherichia coli. Analysis of the attachment (att) sites could locate the possible recombination crossover in the att sequences at position 10-11 (GG) in the last 18 bp of trmE. In silico detection of AGI backbones in the WGS database identified AGI variants in Salmonella enterica (83 strains), Vibrio cholerae (33), E. hormaechei (12), Acinetobacter baumannii (2), most belonging to prevalent clones (ST40, ST69, ST114 and ST25, respectively), but also in E. coli (1) and Klebsiella pneumoniae (1). Two groups of backbone were identified: one similar to AGI1, the other with a short segment from a Shewanella element upstream of ORF A022. The MDR regions were inserted by transposition at the res site in four different positions ATAGG (A. baumannii), CATAG (S. enterica and V. cholerae), TAGGT (S. enterica and K. pneumoniae) and TGCAC (S. enterica) representing four different lineages. In some V. cholerae, E. hormaechei and E. coli, deletion events occurred that eliminated part of the backbone at the left junction. Analysis of the right junction identified a fifth lineage in V. cholerae and E. hormaechei (CCATA). In conclusion, based on the position of the MDR region, AGI-related elements belonged to five groups of closely related genomic islands (AGI1-AGI5), with differences in backbones that evolved independently over time.
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Affiliation(s)
- Eliane Siebor
- Laboratory of Bacteriology, University Hospital of Dijon, Plateau technique de Biologie, BP 37013, 21070 Dijon Cedex, France, and UMR 6249, CNRS Chrono-environnement, Université de Bourgogne Franche-Comté, 25000 Besançon, France
| | - Catherine Neuwirth
- Laboratory of Bacteriology, University Hospital of Dijon, Plateau technique de Biologie, BP 37013, 21070 Dijon Cedex, France, and UMR 6249, CNRS Chrono-environnement, Université de Bourgogne Franche-Comté, 25000 Besançon, France.
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16
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Two New SGI1-LK Variants Found in Proteus mirabilis and Evolution of the SGI1-HKL Group of Salmonella Genomic Islands. mSphere 2020; 5:5/2/e00875-19. [PMID: 32132162 PMCID: PMC7056807 DOI: 10.1128/msphere.00875-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Integrative mobilizable elements belonging to the SGI1-H, -K, and -L Salmonella genomic island 1 (SGI1) variant groups are distinguished by the presence of an alteration in the backbone (IS1359 replaces 2.8 kb of the backbone extending from within traN [S005] to within S009). Members of this SGI1-HKL group have been found in Salmonella enterica serovars and in Proteus mirabilis Two novel variants from this group, designated SGI1-LK1 and SGI1-LK2, were found in the draft genomes of antibiotic-resistant P. mirabilis isolates from two French hospitals. Both variants can be derived from SGI1-PmGUE, a configuration found previously in another P. mirabilis isolate from France. SGI1-LK1 could arise via an IS26-mediated inversion in the complex class 1 integron that duplicated the IS26 element and the target site in IS6100 SGI1-LK1 also has a larger 8.59-kb backbone deletion extending from traN to within S013 and removing traG and traH. However, SGI1-LK1 was mobilized by an IncC plasmid. SGI1-LK2 can be derived from a hypothetical progenitor, SGI1-LK0, that is related to SGI1-PmGUE but lacks the aphA1 gene and one copy of IS26. The integron of SGI1-LK2 could arise via deletion of DNA adjacent to an IS26 and a deletion occurring via homologous recombination between duplicated copies of part of the integron 3'-conserved segment. SGI1-K can also be derived from SGI1-LK0. This would involve an IS26-mediated deletion and an inversion via homologous recombination of a segment between inversely oriented IS26s. Similar events can explain the configuration of the integrons in other SGI1-LK variants.IMPORTANCE Members of the SGI1-HKL subgroup of SGI1-type integrative mobilizable elements have a characteristic alteration in their backbone. They are widely distributed among multiply antibiotic-resistant Salmonella enterica serovars and Proteus mirabilis isolates. The SGI1-K type, found in the globally disseminated multiply antibiotic-resistant Salmonella enterica serovar Kentucky clone ST198 (sequence type 198), and various configurations in the original SGI1-LK group, found in other multiresistant S. enterica serovars and Proteus mirabilis isolates, have complex and highly plastic resistance regions due to the presence of IS26 However, how these complex forms arose and the relationships between them had not been analyzed. Here, a hypothetical progenitor, SGI1-LK0, that can be formed from the simpler SGI1-H is proposed, and the pathways to the formation of new variants, SGI1-LK1 and SGI1-LK2, found in P. mirabilis and other reported configurations via homologous recombination and IS26-mediated events are proposed. This led to a better understanding of the evolution of the SGI1-HKL group.
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de Curraize C, Siebor E, Neuwirth C, Hall RM. SGI0, a relative of Salmonella genomic islands SGI1 and SGI2, lacking a class 1 integron, found in Proteus mirabilis. Plasmid 2019; 107:102453. [PMID: 31705941 DOI: 10.1016/j.plasmid.2019.102453] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/16/2019] [Accepted: 10/25/2019] [Indexed: 01/26/2023]
Abstract
Several groups of integrative mobilizable elements (IMEs) that harbour a class 1 integron carrying antibiotic resistance genes have been found at the 3'-end of the chromosomal trmE gene. Here, a new IME, designated SGI0, was found in trmE in the sequenced and assembled genome of a French clinical, multiply antibiotic resistant Proteus mirabilis strain, Pm1LENAR. SGI0 shares the same gene content as the backbones of SGI1 and SGI2 (overall 97.6% and 97.7% nucleotide identity, respectively) but it lacks a class 1 integron. However, SGI0 is a mosaic made up of segments with >98.5% identity to SGI1 and SGI2 interspersed with segments sharing 74-95% identity indicating that further diverged backbone types exist and that recombination between them is occurring. The structure of SGI1-V, here re-named SGI-V, which lacks two SGI1 (S023 and S024) backbone genes and includes a group of additional genes in the backbone, was re-examined. In regions shared with SGI1, the backbones shared 97.3% overall identity with the differences distributed in patches with various levels of identity. The class 1 integron is also in a slightly different position with the target site duplication AAATT instead of ACTTG for SGI1 and variants, indicating that it was acquired independently. The Pm1LENAR resistance genes are in the chromosome, in Tn7 and an ISEcp1-mobilised segment.
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Affiliation(s)
- Claire de Curraize
- Bacteriology Department, University Hospital Dijon, PTB, BP, 37013, 21070, Dijon Cedex, France; UMR 6249, Chrono-Environnement, PTB, BP 37013, 21070, Dijon Cedex, France; School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
| | - Eliane Siebor
- Bacteriology Department, University Hospital Dijon, PTB, BP, 37013, 21070, Dijon Cedex, France; UMR 6249, Chrono-Environnement, PTB, BP 37013, 21070, Dijon Cedex, France
| | - Catherine Neuwirth
- Bacteriology Department, University Hospital Dijon, PTB, BP, 37013, 21070, Dijon Cedex, France; UMR 6249, Chrono-Environnement, PTB, BP 37013, 21070, Dijon Cedex, France
| | - Ruth M Hall
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
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18
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Hawkey J, Le Hello S, Doublet B, Granier SA, Hendriksen RS, Fricke WF, Ceyssens PJ, Gomart C, Billman-Jacobe H, Holt KE, Weill FX. Global phylogenomics of multidrug-resistant Salmonella enterica serotype Kentucky ST198. Microb Genom 2019; 5. [PMID: 31107206 PMCID: PMC6700661 DOI: 10.1099/mgen.0.000269] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serotype Kentucky can be a common causative agent of salmonellosis, usually associated with consumption of contaminated poultry. Antimicrobial resistance (AMR) to multiple drugs, including ciprofloxacin, is an emerging problem within this serotype. We used whole-genome sequencing (WGS) to investigate the phylogenetic structure and AMR content of 121 S.enterica serotype Kentucky sequence type 198 isolates from five continents. Population structure was inferred using phylogenomic analysis and whole genomes were compared to investigate changes in gene content, with a focus on acquired AMR genes. Our analysis showed that multidrug-resistant (MDR) S.enterica serotype Kentucky isolates belonged to a single lineage, which we estimate emerged circa 1989 following the acquisition of the AMR-associated Salmonella genomic island (SGI) 1 (variant SGI1-K) conferring resistance to ampicillin, streptomycin, gentamicin, sulfamethoxazole and tetracycline. Phylogeographical analysis indicates this clone emerged in Egypt before disseminating into Northern, Southern and Western Africa, then to the Middle East, Asia and the European Union. The MDR clone has since accumulated various substitution mutations in the quinolone-resistance-determining regions (QRDRs) of DNA gyrase (gyrA) and DNA topoisomerase IV (parC), such that most strains carry three QRDR mutations which together confer resistance to ciprofloxacin. The majority of AMR genes in the S. enterica serotype Kentucky genomes were carried either on plasmids or SGI structures. Remarkably, each genome of the MDR clone carried a different SGI1-K derivative structure; this variation could be attributed to IS26-mediated insertions and deletions, which appear to have hampered previous attempts to trace the clone’s evolution using sub-WGS resolution approaches. Several different AMR plasmids were also identified, encoding resistance to chloramphenicol, third-generation cephalosporins, carbapenems and/or azithromycin. These results indicate that most MDR S. enterica serotype Kentucky circulating globally result from the clonal expansion of a single lineage that acquired chromosomal AMR genes 30 years ago, and has continued to diversify and accumulate additional resistances to last-line oral antimicrobials. This article contains data hosted by Microreact.
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Affiliation(s)
- Jane Hawkey
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia.,Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
| | - Simon Le Hello
- Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella , World Health Organization Collaborative Centre for the Typing and Antibiotic Resistance of Salmonella , Institut Pasteur, 75015 Paris, France
| | - Benoît Doublet
- ISP, Institut National de la Recherche Agronomique, Université François Rabelais de Tours, UMR 1282, Nouzilly, France
| | - Sophie A Granier
- Laboratoire de sécurité des aliments, Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail (ANSES), Université PARIS-EST, 94701 Maisons-Alfort, France.,Laboratoire de Fougères, Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail (ANSES), 35306 Fougères, France
| | - Rene S Hendriksen
- Research Group for Genomic Epidemiology, National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - W Florian Fricke
- Department of Microbiome Research and Applied Bioinformatics, University of Hohenheim, Stuttgart, Germany.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Camille Gomart
- Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella , World Health Organization Collaborative Centre for the Typing and Antibiotic Resistance of Salmonella , Institut Pasteur, 75015 Paris, France
| | - Helen Billman-Jacobe
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Science, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Kathryn E Holt
- London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.,Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - François-Xavier Weill
- Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella , World Health Organization Collaborative Centre for the Typing and Antibiotic Resistance of Salmonella , Institut Pasteur, 75015 Paris, France
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19
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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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Dionisio F, Zilhão R, Gama JA. Interactions between plasmids and other mobile genetic elements affect their transmission and persistence. Plasmid 2019; 102:29-36. [DOI: 10.1016/j.plasmid.2019.01.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/24/2019] [Accepted: 01/30/2019] [Indexed: 10/27/2022]
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21
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Matsushita M, Okubo T, Hasegawa T, Matsuo J, Watanabe T, Iwasaki S, Fukumoto T, Hayasaka K, Akizawa K, Shimizu C, Yamaguchi H. Tetrahymena promotes interactive transfer of carbapenemase gene encoded in plasmid between fecal Escherichia coli and environmental Aeromonas caviae. Microbiol Immunol 2019; 62:720-728. [PMID: 30357893 DOI: 10.1111/1348-0421.12656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 10/01/2018] [Accepted: 10/22/2018] [Indexed: 01/06/2023]
Abstract
Tetrahymena can facilitate plasmid transfer among Escherichia coli or from E. coli to Salmonella Enteritidis via vesicle accumulation. In this study, whether ciliates promote the interactive transfer of plasmids encoding blaIMP-1 between fecal E. coli and environmental Aeromonas caviae was investigated. Both bacteria were mixed with or without ciliates and incubated overnight at 30°C. The frequency of plasmid-acquired bacteria was estimated by colony counts using an agar plate containing ceftazidim (CAZ) followed by determination of the minimum inhibitory concentration (MIC). Cultures containing ciliates interactively transferred the plasmid between E. coli and Aeromonas with a frequency of 10-4 to 10-5 . All plasmid-acquired bacteria showed a MIC against CAZ of >128 μg/mL and the plasmid transfer was confirmed by PCR amplification of the blaIMP-1 gene. Fluorescent observation showed that both bacteria accumulated in the same vesicle and that transwell sequestering significantly decreased the transfer frequency. Although ciliates preferentially ingested E. coli rather than A. caviae, both bacteria were co-localized into the same vesicles of ciliates, indicating that their meeting is associated with the gene transfer. Thus, ciliates interactively promote plasmid transfer between E. coli and A. caviae. The results of this study will facilitate control of the spread of multiple-antibiotic resistant bacteria.
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Affiliation(s)
- Mizue Matsushita
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Torahiko Okubo
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Takaki Hasegawa
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Junji Matsuo
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Takanori Watanabe
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
| | - Sumio Iwasaki
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Tatsuya Fukumoto
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Kasumi Hayasaka
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Kozi Akizawa
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Chikara Shimizu
- Hokkaido University Hospital, Nishi-5 Kita-14 Jo, Kita-ku, Sapporo, Hokkaido 060-8648, Japan
| | - Hiroyuki Yamaguchi
- Faculty of Health Sciences, Department of Medical Laboratory Science, Hokkaido University Graduate School of Health Sciences, Nishi-5 Kita-12 Jo, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
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22
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Marquez-Ortiz RA, Haggerty L, Olarte N, Duarte C, Garza-Ramos U, Silva-Sanchez J, Castro BE, Sim EM, Beltran M, Moncada MV, Valderrama A, Castellanos JE, Charles IG, Vanegas N, Escobar-Perez J, Petty NK. Genomic Epidemiology of NDM-1-Encoding Plasmids in Latin American Clinical Isolates Reveals Insights into the Evolution of Multidrug Resistance. Genome Biol Evol 2018; 9:1725-1741. [PMID: 28854628 PMCID: PMC5554438 DOI: 10.1093/gbe/evx115] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2017] [Indexed: 12/21/2022] Open
Abstract
Bacteria that produce the broad-spectrum Carbapenem antibiotic New Delhi Metallo-β-lactamase (NDM) place a burden on health care systems worldwide, due to the limited treatment options for infections caused by them and the rapid global spread of this antibiotic resistance mechanism. Although it is believed that the associated resistance gene blaNDM-1 originated in Acinetobacter spp., the role of Enterobacteriaceae in its dissemination remains unclear. In this study, we used whole genome sequencing to investigate the dissemination dynamics of blaNDM-1-positive plasmids in a set of 21 clinical NDM-1-positive isolates from Colombia and Mexico (Providencia rettgeri, Klebsiella pneumoniae, and Acinetobacter baumannii) as well as six representative NDM-1-positive Escherichia coli transconjugants. Additionally, the plasmids from three representative P. rettgeri isolates were sequenced by PacBio sequencing and finished. Our results demonstrate the presence of previously reported plasmids from K. pneumoniae and A. baumannii in different genetic backgrounds and geographically distant locations in Colombia. Three new previously unclassified plasmids were also identified in P. rettgeri from Colombia and Mexico, plus an interesting genetic link between NDM-1-positive P. rettgeri from distant geographic locations (Canada, Mexico, Colombia, and Israel) without any reported epidemiological links was discovered. Finally, we detected a relationship between plasmids present in P. rettgeri and plasmids from A. baumannii and K. pneumoniae. Overall, our findings suggest a Russian doll model for the dissemination of blaNDM-1 in Latin America, with P. rettgeri playing a central role in this process, and reveal new insights into the evolution and dissemination of plasmids carrying such antibiotic resistance genes.
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Affiliation(s)
- Ricaurte Alejandro Marquez-Ortiz
- Bacterial Molecular Genetics Laboratory, Universidad El Bosque, Bogotá, D.C., Colombia.,The ithree Institute, University of Technology Sydney, New South Wales, Australia
| | - Leanne Haggerty
- The ithree Institute, University of Technology Sydney, New South Wales, Australia
| | | | - Carolina Duarte
- Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, Colombia
| | - Ulises Garza-Ramos
- Instituto Nacional de Salud Pública (INSP), CISEI, Cuernavaca, Morelos, México
| | - Jesus Silva-Sanchez
- Instituto Nacional de Salud Pública (INSP), CISEI, Cuernavaca, Morelos, México
| | - Betsy E Castro
- Bacterial Molecular Genetics Laboratory, Universidad El Bosque, Bogotá, D.C., Colombia
| | - Eby M Sim
- The ithree Institute, University of Technology Sydney, New South Wales, Australia
| | - Mauricio Beltran
- Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, Colombia
| | - María V Moncada
- Bacterial Molecular Genetics Laboratory, Universidad El Bosque, Bogotá, D.C., Colombia
| | | | - Jaime E Castellanos
- Grupo de Patogénesis Infecciosa, Universidad Nacional de Colombia, Bogotá, D.C., Colombia
| | - Ian G Charles
- The ithree Institute, University of Technology Sydney, New South Wales, Australia
| | - Natasha Vanegas
- Bacterial Molecular Genetics Laboratory, Universidad El Bosque, Bogotá, D.C., Colombia.,The ithree Institute, University of Technology Sydney, New South Wales, Australia
| | - Javier Escobar-Perez
- Bacterial Molecular Genetics Laboratory, Universidad El Bosque, Bogotá, D.C., Colombia
| | - Nicola K Petty
- The ithree Institute, University of Technology Sydney, New South Wales, Australia
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PGI2 Is a Novel SGI1-Relative Multidrug-Resistant Genomic Island Characterized in Proteus mirabilis. Antimicrob Agents Chemother 2018; 62:AAC.00019-18. [PMID: 29463532 DOI: 10.1128/aac.00019-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/08/2018] [Indexed: 01/12/2023] Open
Abstract
A novel 61,578-bp genomic island named Proteus genomic island 2 (PGI2) was characterized in Proteus mirabilis of swine origin in China. The 23.85-kb backbone of PGI2 is related to those of Salmonella genomic island 1 and Acinetobacter genomic island 1. The multidrug resistance (MDR) region of PGI2 is a complex class 1 integron containing 14 different resistance genes. PGI2 was conjugally mobilized in trans to Escherichia coli in the presence of a conjugative IncC helper plasmid.
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24
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Compatibility and entry exclusion of IncA and IncC plasmids revisited: IncA and IncC plasmids are compatible. Plasmid 2018; 96-97:7-12. [DOI: 10.1016/j.plasmid.2018.02.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/16/2018] [Accepted: 02/23/2018] [Indexed: 11/17/2022]
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25
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The Obscure World of Integrative and Mobilizable Elements, Highly Widespread Elements that Pirate Bacterial Conjugative Systems. Genes (Basel) 2017; 8:genes8110337. [PMID: 29165361 PMCID: PMC5704250 DOI: 10.3390/genes8110337] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/15/2017] [Accepted: 11/15/2017] [Indexed: 12/22/2022] Open
Abstract
Conjugation is a key mechanism of bacterial evolution that involves mobile genetic elements. Recent findings indicated that the main actors of conjugative transfer are not the well-known conjugative or mobilizable plasmids but are the integrated elements. This paper reviews current knowledge on “integrative and mobilizable elements” (IMEs) that have recently been shown to be highly diverse and highly widespread but are still rarely described. IMEs encode their own excision and integration and use the conjugation machinery of unrelated co-resident conjugative element for their own transfer. Recent studies revealed a much more complex and much more diverse lifecycle than initially thought. Besides their main transmission as integrated elements, IMEs probably use plasmid-like strategies to ensure their maintenance after excision. Their interaction with conjugative elements reveals not only harmless hitchhikers but also hunters that use conjugative elements as target for their integration or harmful parasites that subvert the conjugative apparatus of incoming elements to invade cells that harbor them. IMEs carry genes conferring various functions, such as resistance to antibiotics, that can enhance the fitness of their hosts and that contribute to their maintenance in bacterial populations. Taken as a whole, IMEs are probably major contributors to bacterial evolution.
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26
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Harmer CJ, Hamidian M, Hall RM. pIP40a, a type 1 IncC plasmid from 1969 carries the integrative element GIsul2 and a novel class II mercury resistance transposon. Plasmid 2017; 92:17-25. [PMID: 28577759 DOI: 10.1016/j.plasmid.2017.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 11/27/2022]
Abstract
The 167.5kb sequence of the conjugative IncC plasmid pIP40a, isolated from a Pseudomonas aeruginosa in 1969, was analysed. pIP40a confers resistance to kanamycin, neomycin, ampicillin, sulphonamides and mercuric ions, and several insertions in a type 1 IncC backbone were found, including copies of IS3, Tn1000 and a novel mercury resistance transposon, Tn6182. The antibiotic resistance genes were in two locations. Tn6023, containing the aphA1 kanamycin and neomycin resistance gene, is in a partial copy of Tn1/Tn2/Tn3 (blaTEM, ampicillin resistance) in the kfrA gene, and the sul2 sulphonamide resistance gene is in the integrative element GIsul2 in the position of ARI-B islands. The 11.5kb class II transposon Tn6182 is only distantly related to other class II transposons, with at most 33% identity between the TnpA of Tn6182 and TnpA of other group members. In addition, the inverted repeats are 37bp rather than 38bp, and the likely resolution enzyme is a tyrosine recombinase (TnpI). Re-annotation of GIsul2 revealed genes predicted to confer resistance to arsenate and arsenite, but resistance was not detected. The location of GIsul2 confirms it as the progenitor of the ARI-B configurations seen in many IncC plasmids isolated more recently. However, GIsul2 has integrated at the same site in type 1 and type 2 IncC plasmids, indicating that it targets this site. Analysis of the distribution of GIsul2 revealed that it in addition to its chromosomal integration site at the 3'-end of the guaA gene, it has also integrated into other plasmids, increasing its mobility.
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Affiliation(s)
- Christopher J Harmer
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
| | - Mohammad Hamidian
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Ruth M Hall
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
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27
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Multidrug Resistance Salmonella Genomic Island 1 in a Morganella morganii subsp. morganii Human Clinical Isolate from France. mSphere 2017; 2:mSphere00118-17. [PMID: 28435889 PMCID: PMC5397566 DOI: 10.1128/msphere.00118-17] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/01/2017] [Indexed: 01/19/2023] Open
Abstract
Since its initial identification in epidemic multidrug-resistant Salmonella enterica serovar Typhimurium DT104 strains, several SGI1 variants, SGI1 lineages, and SGI1-related elements (SGI2, PGI1, and AGI1) have been described in many bacterial genera (Salmonella, Proteus, Morganella, Vibrio, Shewanella, etc.). They constitute a family of multidrug resistance site-specific integrative elements acquired by horizontal gene transfer, SGI1 being the best-characterized element. The horizontal transfer of SGI1/PGI1 elements into other genera is of public health concern, notably with regard to the spread of critically important resistance genes such as ESBL and carbapenemase genes. The identification of SGI1 in Morganella morganii raises the issue of (i) the potential for SGI1 to emerge in other human pathogens and (ii) its bacterial host range. Further surveillance and research are needed to understand the epidemiology, the spread, and the importance of the members of this SGI1 family of integrative elements in contributing to antibiotic resistance development. Salmonella genomic island 1 (SGI1) is a multidrug resistance integrative mobilizable element that harbors a great diversity of antimicrobial resistance gene clusters described in numerous Salmonella enterica serovars and also in Proteus mirabilis. A serious threat to public health was revealed in the recent description in P. mirabilis of a SGI1-derivative multidrug resistance island named PGI1 (Proteus genomic island 1) carrying extended-spectrum-β-lactamase (ESBL) and metallo-β-lactamase resistance genes, blaVEB-6 and blaNDM-1, respectively. Here, we report the first description of Salmonella genomic island 1 (SGI1) in a multidrug-resistant clinical Morganella morganii subsp. morganii strain isolated from a patient in France in 2013. Complete-genome sequencing of the strain revealed SGI1 variant SGI1-L carrying resistance genes dfrA15, floR, tetA(G), blaPSE-1 (now referred to as blaCARB-2), and sul1, conferring resistance to trimethoprim, phenicols, tetracyclines, amoxicillin, and sulfonamides, respectively. The SGI1-L variant was integrated into the usual chromosome-specific integration site at the 3′ end of the trmE gene. Beyond Salmonella enterica and Proteus mirabilis, the SGI1 integrative mobilizable element may thus also disseminate its multidrug resistance phenotype in another genus belonging to the Proteae tribe of the family Enterobacteriaceae. IMPORTANCE Since its initial identification in epidemic multidrug-resistant Salmonella enterica serovar Typhimurium DT104 strains, several SGI1 variants, SGI1 lineages, and SGI1-related elements (SGI2, PGI1, and AGI1) have been described in many bacterial genera (Salmonella, Proteus, Morganella, Vibrio, Shewanella, etc.). They constitute a family of multidrug resistance site-specific integrative elements acquired by horizontal gene transfer, SGI1 being the best-characterized element. The horizontal transfer of SGI1/PGI1 elements into other genera is of public health concern, notably with regard to the spread of critically important resistance genes such as ESBL and carbapenemase genes. The identification of SGI1 in Morganella morganii raises the issue of (i) the potential for SGI1 to emerge in other human pathogens and (ii) its bacterial host range. Further surveillance and research are needed to understand the epidemiology, the spread, and the importance of the members of this SGI1 family of integrative elements in contributing to antibiotic resistance development.
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28
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Carraro N, Rivard N, Burrus V, Ceccarelli D. Mobilizable genomic islands, different strategies for the dissemination of multidrug resistance and other adaptive traits. Mob Genet Elements 2017; 7:1-6. [PMID: 28439449 PMCID: PMC5397120 DOI: 10.1080/2159256x.2017.1304193] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 02/15/2017] [Accepted: 03/06/2017] [Indexed: 11/18/2022] Open
Abstract
Mobile genetic elements are near ubiquitous DNA segments that revealed a surprising variety of strategies for their propagation among prokaryotes and between eukaryotes. In bacteria, conjugative elements were shown to be key drivers of evolution and adaptation by efficiently disseminating genes involved in pathogenicity, symbiosis, metabolic pathways, and antibiotic resistance. Conjugative plasmids of the incompatibility groups A and C (A/C) are important vehicles for the dissemination of antibiotic resistance and the consequent global emergence and spread of multi-resistant pathogenic bacteria. Beyond their own mobility, A/C plasmids were also shown to drive the mobility of unrelated non-autonomous mobilizable genomic islands, which may also confer further advantageous traits. In this commentary, we summarize the current knowledge on different classes of A/C-dependent mobilizable genomic islands and we discuss other DNA hitchhikers and their implication in bacterial evolution. Furthermore, we glimpse at the complex genetic network linking autonomous and non-autonomous mobile genetic elements, and at the associated flow of genetic information between bacteria.
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Affiliation(s)
- Nicolas Carraro
- Laboratory of Bacterial Molecular Genetics, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.,Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Rivard
- Laboratory of Bacterial Molecular Genetics, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Vincent Burrus
- Laboratory of Bacterial Molecular Genetics, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Daniela Ceccarelli
- Department of Bacteriology and Epidemiology, Wageningen Bioveterinary Research, Lelystad, the Netherlands
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29
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Salmonella genomic island 1 (SGI1) reshapes the mating apparatus of IncC conjugative plasmids to promote self-propagation. PLoS Genet 2017; 13:e1006705. [PMID: 28355215 PMCID: PMC5389848 DOI: 10.1371/journal.pgen.1006705] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 04/12/2017] [Accepted: 03/20/2017] [Indexed: 11/20/2022] Open
Abstract
IncC conjugative plasmids and Salmonella genomic island 1 (SGI1) and relatives are frequently associated with multidrug resistance of clinical isolates of pathogenic Enterobacteriaceae. SGI1 is specifically mobilized in trans by IncA and IncC plasmids (commonly referred to as A/C plasmids) following its excision from the chromosome, an event triggered by the transcriptional activator complex AcaCD encoded by these helper plasmids. Although SGI1 is not self-transmissible, it carries three genes, traNS, traHS and traGS, coding for distant homologs of the predicted mating pore subunits TraNC, TraHC and TraGC, respectively, encoded by A/C plasmids. Here we investigated the regulation of traNS and traHGS and the role of these three genes in the transmissibility of SGI1. Transcriptional fusion of the promoter sequences of traNS and traHGS to the reporter gene lacZ confirmed that expression of these genes is inducible by AcaCD. Mating experiments using combinations of deletion mutants of SGI1 and the helper IncC plasmid pVCR94 revealed complex interactions between these two mobile genetic elements. Whereas traNC and traHGC are essential for IncC plasmid transfer, SGI1 could rescue null mutants of each individual gene revealing that TraNS, TraHS and TraGS are functional proteins. Complementation assays of individual traC and traS mutants showed that not only do TraNS/HS/GS replace TraNC/HC/GC in the mating pore encoded by IncC plasmids but also that traGS and traHS are both required for SGI1 optimal transfer. In fact, remodeling of the IncC-encoded mating pore by SGI1 was found to be essential to enhance transfer rate of SGI1 over the helper plasmid. Furthermore, traGS was found to be crucial to allow DNA transfer between cells bearing IncC helper plasmids, thereby suggesting that by remodeling the mating pore SGI1 disables an IncC-encoded entry exclusion mechanism. Hence traS genes facilitate the invasion by SGI1 of cell populations bearing IncC plasmids. Acquisition and dissemination of multidrug resistance genes among Enterobacteriaceae is in part driven by IncA and IncC (A/C) conjugative plasmids and Salmonella genomic island 1 (SGI1). Although unrelated, SGI1 relies on the self-transmissible A/C plasmids to disseminate within bacterial populations. The mechanisms allowing SGI1 to hijack the mating apparatus synthesized by A/C plasmids have not been previously established. Here, we show that IncC plasmids trigger the expression of three SGI1-borne genes that code for functional mating pore subunits distantly related to those encoded by the IncC helper plasmids. Our results indicate that these subunits alter the mating pore encoded by IncC plasmids to ensure optimal transfer of SGI1 and promote SGI1 dissemination in cell populations harboring IncC plasmids. Apart from SGI1 and relatives, documented mobilizable genomic islands are not known to code for mating pore components, possibly because of redundancy with those encoded by helper conjugative elements. Instead they usually code for mobilization proteins such as a relaxase and auxiliary factors involved in DNA recognition, processing and docking to the mating pore encoded by their helper conjugative element. From an ecological and epidemiological perspective, the strategy used by SGI1 likely confers a strong competitive advantage to SGI1 over IncC plasmids in clinical settings and could account for the high prevalence of SGI1 and relatives in multidrug-resistant Salmonella enterica and Proteus mirabilis.
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