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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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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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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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de Curraize C, Amoureux L, Bador J, Chapuis A, Siebor E, Clément C, Sauge J, Aho-Glélé LS, Neuwirth C. "Does the Salmonella Genomic Island 1 (SGI1) confer invasiveness properties to human isolates?". BMC Infect Dis 2017; 17:741. [PMID: 29195496 PMCID: PMC5709944 DOI: 10.1186/s12879-017-2847-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/21/2017] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND In the eighties, a multidrug resistant clone of Salmonella Typhimurium DT104 emerged in UK and disseminated worldwide. This clone harbored a Salmonella genomic island 1 (SGI1) that consists of a backbone and a multidrug resistant region encoding for penta-resistance (ampicillin, chloramphenicol/florfenicol, streptomycin/spectinomycin, sulphonamides and tetracycline (ACSSuT)). Several authors suggested that SGI1 might have a potential role in enhancement of virulence properties of Salmonella enterica. The aim of this study was to investigate whether nontyphoidal S. enterica isolates carrying SGI1 cause more severe illness than SGI1 free ones in humans. METHODS From 2011 to 2016, all patients infected with nontyphoidal S. enterica in our hospital were retrospectively included. All nontyphoidal S. enterica isolates preserved in our University Hospital (Dijon, France) were screened for the presence of SGI1. Clinical and biological data of patients were retrospectively collected to evaluate illness severity. Statistical analysis of data was performed by Kruskal-Wallis test or Fisher's exact test for univariate analysis, and by logistic regression for multivariate analysis. RESULTS A total of 100 isolates of S. enterica (22 serovars) were collected. Twelve isolates (12%) belonging to 4 serovars harbored SGI1: S. Typhimurium, S. Infantis, S. Kentucky, S. St Paul. The severity of the disease was age-related (for invasive infection, sepsis and inflammatory response) and was associated with immunosuppression (for invasive infection, sepsis and bacteremia) but not with the presence of SGI1 or with antimicrobial resistance. CONCLUSION A rather high proportion (12%) of human clinical isolates belonging to various serovars (for the first time serovar St Paul) and harboring various antimicrobial resistance profile carried SGI1. Diseases due to SGI1-positive S. enterica or to antimicrobial resistant isolates were not more severe than the others. This first clinical observation should be confirmed by a multicenter and prospective study.
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Affiliation(s)
- Claire de Curraize
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Lucie Amoureux
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Julien Bador
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Angélique Chapuis
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Eliane Siebor
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Claire Clément
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | - Juliette Sauge
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
| | | | - Catherine Neuwirth
- Bacteriology Department, University Hospital Dijon and UMR 6249, PTB, BP 37013, 21070 Dijon Cedex, France
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Determination and Analysis of the Putative AcaCD-Responsive Promoters of Salmonella Genomic Island 1. PLoS One 2016; 11:e0164561. [PMID: 27727307 PMCID: PMC5058578 DOI: 10.1371/journal.pone.0164561] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/12/2016] [Indexed: 12/03/2022] Open
Abstract
The integrative genomic island SGI1 and its variants confer multidrug resistance in numerous Salmonella enterica serovariants and several Proteus mirabilis and Acinetobacter strains. SGI1 is mobilized by the IncA/C family plasmids. The island exploits not only the conjugation apparatus of the plasmid, but also utilizes the plasmid-encoded master regulator AcaCD to induce the excision and formation of its transfer-competent form, which is a key step in the horizontal transfer of SGI1. Triggering of SGI1 excision occurs via the AcaCD-dependent activation of xis gene expression. AcaCD binds in Pxis to an unusually long recognition sequence. Beside the Pxis promoter, upstream regions of four additional SGI1 genes, S004, S005, S012 and S018, also contain putative AcaCD-binding sites. Furthermore, SGI1 also encodes an AcaCD-related activator, FlhDCSGI1, which has no known function. Here, we have analysed the functionality of the putative AcaCD-dependent promoter regions and proved their activation by either AcaCD or FlhDCSGI1. Moreover, we provide evidence that both activators act on the same binding site in Pxis and that FlhDCSGI1 is able to complement the acaCD deletion of the IncA/C family plasmid R16a. We determined the transcription start sites for the AcaCD-responsive promoters and showed that orf S004 is expressed probably from a different start codon than predicted earlier. Additionally, expression of S003 from promoter PS004 was ruled out. Pxis and the four SGI1 promoters examined here also lack obvious -35 promoter box and their promoter profile is consistent with the class II-type activation pathway. Although the role of the four additionally analysed AcaCD/FlhDCSGI1-controlled genes in transfer and/or maintenance of SGI1 is not yet clear, the conservation of the whole region suggests the existence of some selection for their functionality.
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Kiss J, Papp PP, Szabó M, Farkas T, Murányi G, Szakállas E, Olasz F. The master regulator of IncA/C plasmids is recognized by the Salmonella Genomic island SGI1 as a signal for excision and conjugal transfer. Nucleic Acids Res 2015. [PMID: 26209134 PMCID: PMC4605294 DOI: 10.1093/nar/gkv758] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The genomic island SGI1 and its variants, the important vehicles of multi-resistance in Salmonella strains, are integrative elements mobilized exclusively by the conjugative IncA/C plasmids. Integration and excision of the island are carried out by the SGI1-encoded site-specific recombinase Int and the recombination directionality factor Xis. Chromosomal integration ensures the stable maintenance and vertical transmission of SGI1, while excision is the initial step of horizontal transfer, followed by conjugation and integration into the recipient. We report here that SGI1 not only exploits the conjugal apparatus of the IncA/C plasmids but also utilizes the regulatory mechanisms of the conjugation system for the exact timing and activation of excision to ensure efficient horizontal transfer. This study demonstrates that the FlhDC-family activator AcaCD, which regulates the conjugation machinery of the IncA/C plasmids, serves as a signal of helper entry through binding to SGI1 xis promoter and activating SGI1 excision. Promoters of int and xis genes have been identified and the binding site of the activator has been located by footprinting and deletion analyses. We prove that expression of xis is activator-dependent while int is constitutively expressed, and this regulatory mechanism is presumably responsible for the efficient transfer and stable maintenance of SGI1.
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Affiliation(s)
- János Kiss
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - Péter Pál Papp
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - Mónika Szabó
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - Tibor Farkas
- 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
| | - Erik Szakállas
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
| | - Ferenc Olasz
- Agricultural Biotechnology Institute, National Agricultural Research and Innovation Centre, Gödöllő H2100, Hungary
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Tariq M, Lum MR, Chong AW, Amirapu AB, Hameed S, Hirsch AM. A reliable method for the selection and confirmation of transconjugants of plant growth-promoting bacteria especially plant-associated Burkholderia spp. J Microbiol Methods 2015; 117:49-53. [PMID: 26187775 DOI: 10.1016/j.mimet.2015.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/06/2015] [Accepted: 07/07/2015] [Indexed: 11/17/2022]
Abstract
Selectable markers, e.g., antibiotic resistance, for conjugation experiments are not always effective for slow-growing plant growth promoting bacteria such as Burkholderia. We used PCAT medium containing Congo Red for selecting Burkholderia transconjugants. This method allows for the reliable selection of transconjugants of these novel plant growth-promoting bacteria.
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Affiliation(s)
- Mohsin Tariq
- National Institute for Biotechnology & Genetic Engineering, Faisalabad, Pakistan; Government College University Faisalabad, Allama Iqbal Road, Faisalabad, Pakistan
| | - Michelle R Lum
- Department of Biology, Loyola Marymount University, Los Angeles, CA, USA
| | - Allan W Chong
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA
| | - Anjana B Amirapu
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Sohail Hameed
- National Institute for Biotechnology & Genetic Engineering, Faisalabad, Pakistan
| | - Ann M Hirsch
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, USA; Molecular Biology Institute, University of California, Los Angeles, CA, USA.
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Brunelle BW, Bearson BL, Bearson SMD. Chloramphenicol and tetracycline decrease motility and increase invasion and attachment gene expression in specific isolates of multidrug-resistant Salmonella enterica serovar Typhimurium. Front Microbiol 2015; 5:801. [PMID: 25688233 PMCID: PMC4311684 DOI: 10.3389/fmicb.2014.00801] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 12/28/2014] [Indexed: 01/04/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is one of the most common serovars isolated from humans and livestock, and over 35% of these isolates are resistant to three or more antibiotics. Multidrug-resistant (MDR) Salmonella is a public health concern as it is associated with increased morbidity in patients compared to antibiotic sensitive strains, though it is unknown how the antibiotic resistant isolates lead to a more severe infection. Cellular invasion is temporally regulated in Salmonella and normally occurs during late-log and stationary growth. However, our previous work determined that a 30 min exposure to a sub-inhibitory concentration of tetracycline can induce the full invasion phenotype during early-log growth in certain MDR S. Typhimurium isolates. The current study examined whether sub-inhibitory concentrations of other antibiotics could also induce the invasiveness in the same set of isolates. Ampicillin and streptomycin had no effect on invasion, but certain concentrations of chloramphenicol were found to induce invasion in a subset of isolates. Two of the isolates induced by chloramphenicol were also inducible by tetracycline. RNA-seq analyses demonstrated that chloramphenicol and tetracycline both down-regulated motility gene expression, while up-regulating genes associated with attachment, invasion, and intracellular survival. Eleven fimbrial operons were up-regulated, which is notable as only three fimbrial operons were thought to be inducible in culture; six of these up-regulated operons have been reported to play a role in Salmonella persistence in mice. Overall, these data show that the normal progression of the genetic pathways that regulate invasion can be expedited to occur within 30 min due to antibiotic exposure. This altered invasion process due to antibiotics may play a role in the increased intensity and duration of infection observed in patients with MDR Salmonella.
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Affiliation(s)
- Brian W Brunelle
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture Ames, IA, USA
| | - Bradley L Bearson
- Agroecosystems Management Research Unit, National Laboratory for Agriculture and the Environment, Agricultural Research Service, United States Department of Agriculture Ames, IA, USA
| | - Shawn M D Bearson
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture Ames, IA, USA
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Eguale T, Marshall J, Molla B, Bhatiya A, Gebreyes WA, Engidawork E, Asrat D, Gunn JS. Association of multicellular behaviour and drug resistance in Salmonella enterica serovars isolated from animals and humans in Ethiopia. J Appl Microbiol 2014; 117:961-971. [PMID: 24934091 DOI: 10.1111/jam.12579] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/21/2014] [Accepted: 06/12/2014] [Indexed: 11/29/2022]
Abstract
AIMS To determine the association between multicellular behaviour, integron status and antibiotic resistance among 87 Ethiopian Salmonella enterica isolates of animal and human origin. METHODS AND RESULTS Isolates were characterized for their biofilm forming ability, antimicrobial susceptibility and the presence and characteristics of a class 1 integron and Salmonella genomic island 1 (SGI1). The majority of isolates grown at environmental temperatures (20°C) exhibited robust biofilm formation (72·4%) and displayed RDAR colony morphology on Congo red agar plates. The presence of a class 1 integron correlated with the extent of drug resistance and ability to exhibit multicellular behaviour. CONCLUSIONS Although cellulose production and RDAR morphology correlated with increased multicellular behaviour, neither was required for biofilm formation. Contrary to previous reports, colony morphology was generally consistent within a serovar. No integrons were detected in isolates deficient for multicellular behaviour, indicating a potential role of bacterial community formation in transfer of genetic elements among environmental isolates. SIGNIFICANCE AND IMPACT OF STUDY Infection by Salm. enterica is a major public health problem worldwide. The dominance of multidrug resistance and multicellular behaviour in Salmonella isolates of Ethiopian origin highlights a need for integrated surveillance and further detailed phenotypic and molecular studies of isolates from this region.
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Affiliation(s)
- Tadesse Eguale
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia
| | - Joanna Marshall
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Biomedical Research Tower, 460 West 12th, Columbus, OH 43210-1214
| | - Bayleyegn Molla
- Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Rd., Columbus, Ohio 43210
| | - Aditi Bhatiya
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Biomedical Research Tower, 460 West 12th, Columbus, OH 43210-1214
| | - Wondwossen A Gebreyes
- Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Rd., Columbus, Ohio 43210
| | - Ephrem Engidawork
- Department of Pharmacology School of Pharmacy, College of Health Sciences, Addis Ababa University, Churchill Avenue, P.O. Box 1176, Addis Ababa, Ethiopia
| | - Daniel Asrat
- Department of Microbiology, Immunology & Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Churchill Avenue, P.O. Box 9086, Addis Ababa, Ethiopia
| | - John S Gunn
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Biomedical Research Tower, 460 West 12th, Columbus, OH 43210-1214
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Staib L, Fuchs TM. From food to cell: nutrient exploitation strategies of enteropathogens. MICROBIOLOGY-SGM 2014; 160:1020-1039. [PMID: 24705229 DOI: 10.1099/mic.0.078105-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Upon entering the human gastrointestinal tract, foodborne bacterial enteropathogens encounter, among numerous other stress conditions, nutrient competition with the host organism and the commensal microbiota. The main carbon, nitrogen and energy sources exploited by pathogens during proliferation in, and colonization of, the gut have, however, not been identified completely. In recent years, a huge body of literature has provided evidence that most enteropathogens are equipped with a large set of specific metabolic pathways to overcome nutritional limitations in vivo, thus increasing bacterial fitness during infection. These adaptations include the degradation of myo-inositol, ethanolamine cleaved from phospholipids, fucose derived from mucosal glycoconjugates, 1,2-propanediol as the fermentation product of fucose or rhamnose and several other metabolites not accessible for commensal bacteria or present in competition-free microenvironments. Interestingly, the data reviewed here point to common metabolic strategies of enteric pathogens allowing the exploitation of nutrient sources that not only are present in the gut lumen, the mucosa or epithelial cells, but also are abundant in food. An increased knowledge of the metabolic strategies developed by enteropathogens is therefore a key factor to better control foodborne diseases.
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Affiliation(s)
- Lena Staib
- ZIEL, Abteilung Mikrobiologie, and Lehrstuhl für Mikrobielle Ökologie, Fakultät für Grundlagen der Biowissenschaften, Wissenschaftszentrum Weihenstephan, Technische Universität München, Weihenstephaner Berg 3, 85350 Freising, Germany
| | - Thilo M Fuchs
- ZIEL, Abteilung Mikrobiologie, and Lehrstuhl für Mikrobielle Ökologie, Fakultät für Grundlagen der Biowissenschaften, Wissenschaftszentrum Weihenstephan, Technische Universität München, Weihenstephaner Berg 3, 85350 Freising, Germany
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Tetracycline accelerates the temporally-regulated invasion response in specific isolates of multidrug-resistant Salmonella enterica serovar Typhimurium. BMC Microbiol 2013; 13:202. [PMID: 24020473 PMCID: PMC3854800 DOI: 10.1186/1471-2180-13-202] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 09/02/2013] [Indexed: 12/21/2022] Open
Abstract
Background Multidrug-resistant (MDR) Salmonella isolates are associated with increased morbidity compared to antibiotic-sensitive strains and are an important health and safety concern in both humans and animals. Salmonella enterica serovar Typhimurium is a prevalent cause of foodborne disease, and a considerable number of S. Typhimurium isolates from humans and livestock are resistant to three or more antibiotics. The majority of these MDR S. Typhimurium isolates are resistant to tetracycline, a commonly used and clinically and agriculturally relevant antibiotic. Because exposure of drug-resistant bacteria to antibiotics can affect cellular processes associated with virulence, such as invasion, we investigated the effect tetracycline had on the invasiveness of tetracycline-resistant MDR S. Typhimurium isolates. Results The isolates selected and tested were from two common definitive phage types of S. Typhimurium, DT104 and DT193, and were resistant to tetracycline and at least three other antibiotics. Although Salmonella invasiveness is temporally regulated and normally occurs during late-log growth phase, tetracycline exposure induced the full invasive phenotype in a cell culture assay during early-log growth in several DT193 isolates. No changes in invasiveness due to tetracycline exposure occurred in the DT104 isolates during early-log growth or in any of the isolates during late-log growth. Real-time PCR was used to test expression of the virulence genes hilA, prgH, and invF, and these genes were significantly up-regulated during early-log growth in most isolates due to tetracycline exposure; however, increased virulence gene expression did not always correspond with increased invasion, and therefore was not an accurate indicator of elevated invasiveness. This is the first report to assess DT193 isolates, as well as the early-log growth phase, in response to tetracycline exposure, and it was the combination of both parameters that was necessary to observe the induced invasion phenotype. Conclusions In this report, we demonstrate that the invasiveness of MDR S. Typhimurium can be modulated in the presence of tetracycline, and this effect is dependent on growth phase, antibiotic concentration, and strain background. Identifying the conditions necessary to establish an invasive phenotype is important to elucidate the underlying factors associated with increased virulence of MDR Salmonella.
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 616] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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Abstract
The analysis of the genomes of bacterial pathogens indicates that they have acquired their pathogenic capability by incorporating different genetic elements through horizontal gene transfer. The ancestors of virulent bacteria, as well as the origin of virulence determinants, lay most likely in the environmental microbiota. Studying the role that these determinants may have in non-clinical ecosystems is thus of value for understanding in detail the evolution and the ecology of bacterial pathogens. In this article, I propose that classical virulence determinants might be relevant for basic metabolic processes (for instance iron-uptake systems) or in modulating prey/predator relationships (toxins) in natural, non-infective ecosystems. The different role that horizontal gene transfer and mutation may have in the evolution of bacterial pathogens either for their speciation or in short-sighted evolution processes is also discussed.
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Affiliation(s)
- José L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Darwin 3, Cantoblanco, 28049-Madrid, Spain.
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14
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Kiss J, Nagy B, Olasz F. Stability, entrapment and variant formation of Salmonella genomic island 1. PLoS One 2012; 7:e32497. [PMID: 22384263 PMCID: PMC3285670 DOI: 10.1371/journal.pone.0032497] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/27/2012] [Indexed: 11/26/2022] Open
Abstract
Background The Salmonella genomic island 1 (SGI1) is a 42.4 kb integrative mobilizable element containing several antibiotic resistance determinants embedded in a complex integron segment In104. The numerous SGI1 variants identified so far, differ mainly in this segment and the explanations of their emergence were mostly based on comparative structure analyses. Here we provide experimental studies on the stability, entrapment and variant formation of this peculiar gene cluster originally found in S. Typhimurium. Methodology/Principal Findings Segregation and conjugation tests and various molecular techniques were used to detect the emerging SGI1 variants in Salmonella populations of 17 Salmonella enterica serovar Typhimurium DT104 isolates from Hungary. The SGI1s in these isolates proved to be fully competent in excision, conjugal transfer by the IncA/C helper plasmid R55, and integration into the E. coli chromosome. A trap vector has been constructed and successfully applied to capture the island on a plasmid. Monitoring of segregation of SGI1 indicated high stability of the island. SGI1-free segregants did not accumulate during long-term propagation, but several SGI1 variants could be obtained. Most of them appeared to be identical to SGI1-B and SGI1-C, but two new variants caused by deletions via a short-homology-dependent recombination process have also been detected. We have also noticed that the presence of the conjugation helper plasmid increased the formation of these deletion variants considerably. Conclusions/Significance Despite that excision of SGI1 from the chromosome was proven in SGI1+Salmonella populations, its complete loss could not be observed. On the other hand, we demonstrated that several variants, among them two newly identified ones, arose with detectable frequencies in these populations in a short timescale and their formation was promoted by the helper plasmid. This reflects that IncA/C helper plasmids are not only involved in the horizontal spreading of SGI1, but may also contribute to its evolution.
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Affiliation(s)
- János Kiss
- Agricultural Biotechnology Center, Gödöllő, Hungary.
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15
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Hall RM. Salmonella genomic islands and antibiotic resistance in Salmonella enterica. Future Microbiol 2011; 5:1525-38. [PMID: 21073312 DOI: 10.2217/fmb.10.122] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Antibiotic resistance in several Salmonella enterica serovars that cause gastrointestinal disease in humans is due to a set of related genomic islands carrying a class 1 integron, which carries the resistance genes. Salmonella genomic island 1 (SGI1), the first island of this type, was found in S. enterica serovar Typhimurium DT104 isolates, which are resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides and tetracycline. Several Salmonella serovars and Proteus mirablis have since been shown to harbor SGI1 or related islands carrying various sets of resistance genes and some distinct groups have emerged. SGI1 is an integrative mobilizable element and can be transferred experimentally into Escherichia coli. However, within serovars, isolates recovered from different parts of the world appear to be clonal, indicating that SGI1 movement may be rare. Potential reservoirs in food-producing animals or in ornamental fish have been identified for some serovars.
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Affiliation(s)
- Ruth M Hall
- School of Molecular Bioscience, The University of Sydney, NSW 2006, Australia.
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16
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Foodborne antimicrobial resistance as a biological hazard - Scientific Opinion of the Panel on Biological Hazards. EFSA J 2008. [DOI: 10.2903/j.efsa.2008.765] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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17
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Andrysiak AK, Olson AB, Tracz DM, Dore K, Irwin R, Ng LK, Gilmour MW. Genetic characterization of clinical and agri-food isolates of multi drug resistant Salmonella enterica serovar Heidelberg from Canada. BMC Microbiol 2008; 8:89. [PMID: 18538029 PMCID: PMC2438365 DOI: 10.1186/1471-2180-8-89] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 06/06/2008] [Indexed: 11/23/2022] Open
Abstract
Background Salmonella enterica serovar Heidelberg ranks amongst the most prevalent causes of human salmonellosis in Canada and an increase in resistance to extended spectrum cephalosporins (ESC) has been observed by the Canadian Integrated Program for Antimicrobial Resistance Surveillance. This study examined the genetic relationship between S. Heidelberg isolates from livestock, abattoir, retail meat, and clinical human specimens to determine whether there was a link between the emergence of MDR S. Heidelberg in chicken agri-food sources and the simultaneous increase of MDR S. Heidelberg in human clinical samples. Results Chromosomal genetic homogeneity was observed by pulsed-field gel electrophoresis (PFGE), DNA sequence-based typing (SBT) and DNA microarray-based comparative genomic hybridization (CGH). Sixty one percent of isolates were indistinguishable by PFGE conducted using XbaI and BlnI restriction enzymes. An additional 15% of isolates had PFGE patterns that were closely related to the main cluster. SBT did not identify DNA polymorphisms and CGH revealed only genetic differences between the reference S. Typhimurium strain and S. Heidelberg isolates. Genetic variation observed by CGH between S. Heidelberg isolates could be attributed to experimental variation. Alternatively, plasmid content was responsible for differences in antimicrobial susceptibility, and restriction fragment length polymorphism (RFLP) analyses followed by replicon typing identified two divergent plasmid types responsible for ESC resistance. Conclusion Due to the overall limited genetic diversity among the isolates, it was not possible to identify variable traits that would be suitable for source tracking between human and agri-food isolates of S. Heidelberg in Canada.
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Affiliation(s)
- Ashleigh K Andrysiak
- Bacteriology and Enteric Diseases Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
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18
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Doublet B, Golding GR, Mulvey MR, Cloeckaert A. Secondary chromosomal attachment site and tandem integration of the mobilizable Salmonella genomic island 1. PLoS One 2008; 3:e2060. [PMID: 18446190 PMCID: PMC2297512 DOI: 10.1371/journal.pone.0002060] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 03/16/2008] [Indexed: 11/23/2022] Open
Abstract
Background The Salmonella genomic island 1 is an integrative mobilizable element (IME) originally identified in epidemic multidrug-resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) DT104. SGI1 contains a complex integron, which confers various multidrug resistance phenotypes due to its genetic plasticity. Previous studies have shown that SGI1 integrates site-specifically into the S. enterica, Escherichia coli, or Proteus mirabilis chromosome at the 3′ end of thdF gene (attB site). Methodology/Principal Findings Here, we report the transfer of SGI1 to a ΔthdF mutant of S. Typhimurium LT2. In the absence of thdF, the frequency of transconjugant formation was reduced by around thirty times of magnitude. Through DNA sequencing SGI1 was shown to integrate specifically into a secondary attachment site (2ndattB), which is located in the intergenic region between the chromosomal sodB and purR genes. At this 2ndattB site, we found that a significant fraction of SGI1 transconjugants (43% of wild type and 100% of ΔthdF mutant) contained tandem SGI1 arrays. Moreover, in wild type S. Typhimurium LT2 transconjugants, SGI1 integrated into both attachment sites, i.e., thdF and sodB-purR. The formation of SGI1 tandem arrays occurred in both specific attB sites. There was heterogeneity in the size of the SGI1 tandem arrays detected in single transconjugant colonies. Some arrays consisted as far as six SGI1s arranged in tandem. These tandem arrays were shown to persist during serial passages with or without antibiotic selection pressure. Conclusions/Significance The ability of integration into two distinct chromosomal sites and tandem array formation of SGI1 could contribute to its spread and persistence. The existence of a secondary attachment site in the Salmonella chromosome has potential implications for the mobility of SGI1, which may integrate in other attachment sites of other bacterial pathogens that do not possess the 1st or 2nd specific SGI1 attB sites of Salmonella.
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Affiliation(s)
- Benoît Doublet
- INRA, UR1282, Infectiologie Animale et Santé Publique, Nouzilly, France.
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Boyd DA, Shi X, Hu QH, Ng LK, Doublet B, Cloeckaert A, Mulvey MR. Salmonella genomic island 1 (SGI1), variant SGI1-I, and new variant SGI1-O in proteus mirabilis clinical and food isolates from China. Antimicrob Agents Chemother 2008; 52:340-4. [PMID: 18025121 PMCID: PMC2223879 DOI: 10.1128/aac.00902-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 08/22/2007] [Accepted: 10/25/2007] [Indexed: 11/20/2022] Open
Abstract
Salmonella genomic island 1 (SGI1) and variants (SGI1-I and the new variant SGI1-O) were mapped in five strains of Proteus mirabilis isolated from humans and food in China. Sequencing showed that SGI1 and variants were integrated at the 3' end of the chromosomal thdF gene as previously described for Salmonella strains.
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Affiliation(s)
- David A Boyd
- National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Canada R3E 3R2
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20
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Malcova M, Hradecka H, Karpiskova R, Rychlik I. Biofilm formation in field strains of Salmonella enterica serovar Typhimurium: identification of a new colony morphology type and the role of SGI1 in biofilm formation. Vet Microbiol 2007; 129:360-6. [PMID: 18242887 DOI: 10.1016/j.vetmic.2007.12.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 12/05/2007] [Accepted: 12/07/2007] [Indexed: 10/22/2022]
Abstract
In this study we examined the extent of biofilm formation in field strains of Salmonella enterica serovar Typhimurium (S. Typhimurium), an important foodborne pathogen. Ninety-four field strains of S. Typhimurium were tested for their ability to form biofilm and components contributing to its formation. Most S. Typhimurium strains were highly capable of biofilm formation except for strains of phage type DT2 originating from pigeons. The most efficient biofilm forming strains were those of phage type DT104 positive for Salmonella genomic island 1 (SGI1). A comparison of SGI1 positive and negative strains indicated that the increased biofilm formation of SGI1 positive strains was associated with the presence of this genomic island. Finally, in five strains we found an alternative strategy of biofilm formation independent of curli fimbriae and cellulose production but solely dependent on an overproduction of capsular polysaccharide. Due to a mucoid and brown appearance on Congo Red agar we designated these strains as belonging to the SBAM (smooth brown and mucoid) morphotype.
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Affiliation(s)
- M Malcova
- Veterinary Research Institute, Brno, Czech Republic
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21
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Walsh C, Duffy G, Nally P, O’Mahony R, McDowell D, Fanning S. Transfer of ampicillin resistance from Salmonella Typhimurium DT104 to Escherichia coli K12 in food. Lett Appl Microbiol 2007; 46:210-5. [DOI: 10.1111/j.1472-765x.2007.02288.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Olson AB, Andrysiak AK, Tracz DM, Guard-Bouldin J, Demczuk W, Ng LK, Maki A, Jamieson F, Gilmour MW. Limited genetic diversity in Salmonella enterica serovar Enteritidis PT13. BMC Microbiol 2007; 7:87. [PMID: 17908316 PMCID: PMC2137926 DOI: 10.1186/1471-2180-7-87] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 10/01/2007] [Indexed: 11/10/2022] Open
Abstract
Background Salmonella enterica serovar Enteritidis has emerged as a significant foodborne pathogen throughout the world and is commonly characterized by phage typing. In Canada phage types (PT) 4, 8 and 13 predominate and in 2005 a large foodborne PT13 outbreak occurred in the province of Ontario. The ability to link strains during this outbreak was difficult due to the apparent clonality of PT13 isolates in Canada, as there was a single dominant pulsed-field gel electrophoresis (PFGE) profile amongst epidemiologically linked human and food isolates as well as concurrent sporadic strains. The aim of this study was to perform comparative genomic hybridization (CGH), DNA sequence-based typing (SBT) genomic analyses, plasmid analyses, and automated repetitive sequence-based PCR (rep-PCR) to identify epidemiologically significant traits capable of subtyping S. Enteritidis PT13. Results CGH using an oligonucleotide array based upon chromosomal coding sequences of S. enterica serovar Typhimurium strain LT2 and the Salmonella genomic island 1 successfully determined major genetic differences between S. Typhimurium and S. Enteritidis PT13, but no significant strain-to-strain differences were observed between S. Enteritidis PT13 isolates. Individual loci (safA and fliC) that were identified as potentially divergent in the CGH data set were sequenced in a panel of S. Enteritidis strains, and no differences were detected between the PT13 strains. Additional sequence-based typing was performed at the fimA, mdh, manB, cyaA, citT, caiC, dmsA, ratA and STM0660 loci. Similarly, no diversity was observed amongst PT13 strains. Variation in plasmid content between PT13 strains was observed, but macrorestriction with BglII did not identify further differences. Automated rep-PCR patterns were variable between serovars, but S. Enteritidis PT13 strains could not be differentiated. Conclusion None of the methods identified any significant variation between PT13 strains. Greater than 11,300 base pairs of sequence for each of seven S. Enteritidis PT13 strains were analyzed without detecting a single polymorphic site, although diversity between different phage types of S. Enteritidis was observed. These data suggest that Canadian S. Enteritidis PT13 strains are highly related genetically.
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Affiliation(s)
- Adam B Olson
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Ashleigh K Andrysiak
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
- Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Dobryan M Tracz
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Jean Guard-Bouldin
- United States Department of Agricultural, Agricultural Research Service, Athens, GA, USA
| | - Walter Demczuk
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Lai-King Ng
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
- Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Maki
- Ontario Central Public Health Laboratory, Ministry of Health and Long-Term Care, Toronto, ON, Canada
| | - Frances Jamieson
- Ontario Central Public Health Laboratory, Ministry of Health and Long-Term Care, Toronto, ON, Canada
| | - Matthew W Gilmour
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
- Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada
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