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Perdomo A, Webb HE, Bugarel M, Friedman CR, Francois Watkins LK, Loneragan GH, Calle A. First Known Report of mcr-Harboring Enterobacteriaceae in the Dominican Republic. Int J Environ Res Public Health 2023; 20:5123. [PMID: 36982034 PMCID: PMC10049167 DOI: 10.3390/ijerph20065123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Colistin is a last-resort antibiotic used to treat infections caused by multidrug-resistant Gram-negative bacteria. People with a history of travel to the Dominican Republic have become sick with pathogenic bacteria carrying the mobile colistin resistance gene, mcr-1, during and after traveling. This investigation aimed to identify mcr genes in Enterobacteriaceae isolated from food animal sources in the Dominican Republic. Three hundred and eleven samples were tested, from which 1354 bacterial isolates were obtained. Real-time PCR tests showed that 70.7% (220 out of 311) of the samples and 3.2% (44 out of 1354) of the isolates tested positive for the mcr gene. All RT-PCR presumptive mcr-positive isolates (n = 44) and a subset (n = 133) of RT-PCR presumptive mcr-negative isolates were subjected to whole-genome sequencing. WGS analysis showed that 39 isolates carried the mcr gene, with 37 confirmed as positive through RT-PCR and two as negative. Further, all of the mcr-positive genomes were identified as Escherichia coli and all contained a IncX4 plasmid replicon. Resistant determinants for other antibiotics important for human health were found in almost all isolates carrying mcr genes.
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Affiliation(s)
- Angela Perdomo
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX 79409, USA
| | - Hattie E. Webb
- Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Marie Bugarel
- Division of Research and Development Resources, BioMérieux, 69795 Lyon, France
| | - Cindy R. Friedman
- Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Louise K. Francois Watkins
- Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Guy H. Loneragan
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX 79409, USA
| | - Alexandra Calle
- School of Veterinary Medicine, Texas Tech University, Amarillo, TX 79409, USA
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Manishimwe R, Moncada PM, Bugarel M, Scott HM, Loneragan GH. Antibiotic resistance among Escherichia coli and Salmonella isolated from dairy cattle feces in Texas. PLoS One 2021; 16:e0242390. [PMID: 33961628 PMCID: PMC8104409 DOI: 10.1371/journal.pone.0242390] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 04/24/2021] [Indexed: 12/31/2022] Open
Abstract
In several developing countries, studies on antimicrobial resistance among bacteria from food animals are rare mostly because of under-resourced laboratories. The objective of this study was to develop and field-test a low cost protocol to estimate the isolate- and sample-level prevalence of resistance to critically important antibiotics among Escherichia coli and Salmonella isolated from dairy cattle feces. Using a predesigned protocol, fecal samples were collected to isolate non-type-specific E. coli and Salmonella using selective media without antibiotic supplements. Besides, samples were screened for E. coli and Salmonella isolates not susceptible to third-generation cephalosporins and quinolones using selective media supplemented with cefotaxime (1.0 μg/mL) and ciprofloxacine (0.5 μg/mL), respectively. All bacterial isolates were further tested for antibiotic susceptibility using disk diffusion. Bacterial isolates not susceptible to third-generation cephalosporins were tested for extended spectrum beta-lactamase (ESBL) phenotype using the combination disk test. Molecular methods were performed on selected bacterial isolates to identify and distinguish genetic determinants associated with the observed phenotypes. Among 85 non-type-specific E. coli isolated from MacConkey agar without antibiotics, the isolate-level prevalence of resistance to tetracycline was the highest (8.2%). Among 37 E. coli recovered from MacConkey agar with cefotaxime, 56.8% were resistant ceftriaxone. Among 22 E. coli isolates recovered from MacConkey agar with ciprofloxacin, 77.3% and 54.5% were resistant to nalidixic acid and ciprofloxacin, respectively. Sixteen Salmonella were isolated and only one demonstrated any resistance (i.e., single resistance to streptomycin). Among E. coli isolates not susceptible to ceftriaxone, an AmpC phenotype was more common than an ESBL phenotype (29 versus 10 isolates, respectively). Whole genome sequencing showed that phenotypic profiles of antibiotic resistance detected were generally substantiated by genotypic profiles. The tested protocol is suited to detecting and estimating prevalence of antimicrobial resistance in bacteria isolated from food animal feces in resource-limited laboratories in the developing world.
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Affiliation(s)
- Rosine Manishimwe
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
- Department of Veterinary Medicine, College of Agriculture, Animal Sciences and Veterinary Medicine, University of Rwanda, Nyagatare, Rwanda
- * E-mail: ,
| | - Paola M. Moncada
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Marie Bugarel
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - H. Morgan Scott
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Guy H. Loneragan
- School of Veterinary Medicine, Texas Tech University, Amarillo, Texas, United States of America
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Ramirez-Hernandez A, Bugarel M, Kumar S, Thippareddi H, Brashears MM, Sanchez-Plata MX. Phenotypic and Genotypic Characterization of Antimicrobial Resistance in Salmonella Strains Isolated from Chicken Carcasses and Parts Collected at Different Stages during Processing. J Food Prot 2019; 82:1793-1801. [PMID: 31545106 DOI: 10.4315/0362-028x.jfp-19-056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chicken carcass and parts rinsate samples and fecal samples were collected at different stages in a commercial poultry processing facility. Microbiological analysis was conducted to determine the levels of multiple indicator microorganisms and prevalence of Salmonella. Antibiotic susceptibility testing was conducted on Salmonella isolates to determine antimicrobial resistance profiles. Whole genome sequencing was performed for tracing isolates in the processing chain, serotyping, and determining genetic features associated with virulence and antimicrobial resistance in the bacterial genome. The overall contamination rate was 55% for Salmonella. Prevalence increased by 80% in chicken parts compared with the previous processing site (postchill carcasses), suggesting possible cross-contamination during the cutting and deboning processes. The levels of indicator organisms were reduced significantly from the prescalding to the parts processing sites, by 3.22 log CFU/mL for aerobic plate count, 3.92 log CFU/mL for E. coli, 3.70 log CFU/mL for coliforms, and 3.40 log CFU/mL for Enterobacteriaceae. The most frequent resistance in Salmonella was associated with tetracycline (49 of 50, 98%) and streptomycin (43 of 50, 86%). Some Salmonella isolates featured resistance to the cephems class of antibiotics (up to 15%). Whole genome sequencing analysis of Salmonella isolates identified nine different clonal populations distributed throughout the samples taken at different stages; serotype Kentucky was the most commonly isolated. This study provides insights into microbial profiling and antibiotic-resistant strains of chicken rinsate samples during poultry processing.
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Affiliation(s)
- Alejandra Ramirez-Hernandez
- Animal and Food Sciences Department, Texas Tech University, Lubbock, Texas 79409 (ORCID: https://orcid.org/0000-0001-9580-5773 [A.R.-H.])
| | - Marie Bugarel
- Animal and Food Sciences Department, Texas Tech University, Lubbock, Texas 79409 (ORCID: https://orcid.org/0000-0001-9580-5773 [A.R.-H.])
| | - Sanjay Kumar
- Poultry Science Department, University of Georgia, Athens, Georgia 30602, USA
| | | | - Mindy M Brashears
- Animal and Food Sciences Department, Texas Tech University, Lubbock, Texas 79409 (ORCID: https://orcid.org/0000-0001-9580-5773 [A.R.-H.])
| | - Marcos X Sanchez-Plata
- Animal and Food Sciences Department, Texas Tech University, Lubbock, Texas 79409 (ORCID: https://orcid.org/0000-0001-9580-5773 [A.R.-H.])
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Ayala DI, Cook PW, Franco JG, Bugarel M, Kottapalli KR, Loneragan GH, Brashears MM, Nightingale KK. A Systematic Approach to Identify and Characterize the Effectiveness and Safety of Novel Probiotic Strains to Control Foodborne Pathogens. Front Microbiol 2019; 10:1108. [PMID: 31156609 PMCID: PMC6533568 DOI: 10.3389/fmicb.2019.01108] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/01/2019] [Indexed: 12/16/2022] Open
Abstract
A total of 44 lactic acid bacteria (LAB) strains originally isolated from cattle feces and different food sources were screened for their potential probiotic features. The antimicrobial activity of all isolates was tested by well-diffusion assay and competitive exclusion on broth against Salmonella Montevideo, Escherichia coli O157:H7 and Listeria monocytogenes strain N1-002. Thirty-eight LAB strains showed antagonistic effect against at least one of the pathogens tested in this study. Improved inhibitory effect was observed against L. monocytogenes with zones of inhibition up to 24 mm when LAB overnight cultures were used, and up to 21 mm when cell-free filtrates were used. For E. coli O157:H7 and Salmonella maximum inhibitions of 12 and 11.5 mm were observed, respectively. On broth, 43 strains reduced L. monocytogenes up to 9.06 log10 CFU/ml, 41 reduced E. coli O157:H7 up to 0.84 log10 CFU/ml, and 32 reduced Salmonella up to 0.94 log10 CFU/ml 24 h after co-inoculation. Twenty-eight LAB isolates that exhibited the highest inhibitory effect among pathogens were further analyzed to determine their antimicrobial resistance profile, adhesion potential, and cytotoxicity to Caco-2 cells. All LAB strains tested were susceptible to ampicillin, linezolid, and penicillin. Twenty-six were able to adhere to Caco-2 cells, five were classified as highly adhesive with > 40 bacterial cells/Caco-2 cells. Low cytotoxicity percentages were observed for the candidate LAB strains with values ranging from -5 to 8%. Genotypic identification by whole genome sequencing confirmed all as members of the LAB group; Enterococcus was the genus most frequently isolated with 21 isolates, followed by Pediococcus with 4, and Lactobacillus with 3. In this study, a systematic approach was used for the improved identification of novel LAB strains able to exert antagonistic effect against important foodborne pathogens. Our findings suggest that the selected panel of LAB probiotic strains can be used as biocontrol cultures to inhibit and/or reduce the growth of L. monocytogenes, Salmonella, and E. coli O157:H7 in different matrices, and environments.
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Affiliation(s)
- Diana I Ayala
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
| | - Peter W Cook
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States.,Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Jorge G Franco
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
| | - Marie Bugarel
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
| | - Kameswara R Kottapalli
- Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX, United States
| | - Guy H Loneragan
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
| | - Mindy M Brashears
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
| | - Kendra K Nightingale
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, United States
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Bougreau M, Ascencio K, Bugarel M, Nightingale K, Loneragan G. Yeast species isolated from Texas High Plains vineyards and dynamics during spontaneous fermentations of Tempranillo grapes. PLoS One 2019; 14:e0216246. [PMID: 31048913 PMCID: PMC6497380 DOI: 10.1371/journal.pone.0216246] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/16/2019] [Indexed: 12/24/2022] Open
Abstract
Vineyards and grape musts harbor complex locally specific microbial communities, among which yeast species can be responsible of spontaneous alcoholic fermentation. Although relying on indigenous yeast can be a risk for winemaking, local yeast diversity is associated with complexity and stronger identity of the wine produced, compared to inoculated alcoholic fermentation with commercial yeast strains. In this context, the main yeast species present on grapes, leaves and soils of Tempranillo and Cabernet Sauvignon vineyards in the hot semi-arid climate of the Texas High Plains area were investigated, as well as the presence and dynamics of yeast species during spontaneous fermentations of Tempranillo grapes from the same vineyards. Molecular characterization of yeast species was performed using culture-dependent 5.8S-ITS restriction fragment length polymorphism method and sequencing. Yeast species recovered from grapes, leaves, and soils were mainly dominated by Aureobasidium pullulans, Cryptococcus species, Filobasidium species and Naganishia species, typical members of the vineyard environment. One isolate of potential enological interest, Lachancea thermotolerans, a fermenting yeast with potential in must acidification, was recovered from the vineyard environment. However, spontaneous alcoholic fermentations revealed the presence of fermenting yeast species, including Saccharomyces cerevisiae, Lachancea thermotolerans and Hanseniaspora species. The presence of the three aforementioned species is of extreme interest for winemaking in the Texas High Plains area. Indeed, Saccharomyces cerevisiae is the model for alcoholic fermentation, Hanseniaspora species have been shown to improve palatability of wines, and Lachancea thermotolerans has become of increasing interest due to its potential to acidify musts and palatability. One of the main characteristics of grapes grown in the Texas High Plains area being the lack of acidity, focusing on these three yeast species could promote the development of locally oriented started cultures for the production of wines with a stronger local identity.
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Affiliation(s)
- Matthias Bougreau
- Department of Plant and Soil Sciences, Texas Tech University, Lubbock, Texas, United States of America
- * E-mail:
| | - Kenia Ascencio
- Department of Animal and Food Sciences, International Center for Food Industry Excellence, Texas Tech University, Lubbock, Texas, United States of America
| | - Marie Bugarel
- Department of Animal and Food Sciences, International Center for Food Industry Excellence, Texas Tech University, Lubbock, Texas, United States of America
| | - Kendra Nightingale
- Department of Animal and Food Sciences, International Center for Food Industry Excellence, Texas Tech University, Lubbock, Texas, United States of America
| | - Guy Loneragan
- Department of Animal and Food Sciences, International Center for Food Industry Excellence, Texas Tech University, Lubbock, Texas, United States of America
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Ayala DI, Chen JC, Bugarel M, Loneragan GH, den Bakker HC, Kottapalli KR, Brashears MM, Nightingale KK. Molecular detection and quantification of viable probiotic strains in animal feedstuffs using the commercial direct fed microbial Lactobacillus animalis NP51 as a model. J Microbiol Methods 2018; 149:36-43. [PMID: 29673790 DOI: 10.1016/j.mimet.2018.04.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/16/2018] [Accepted: 04/16/2018] [Indexed: 01/04/2023]
Abstract
Lactobacillus animalis NP51 is a direct-fed microbial strain (DFM) extensively used as a pre-harvest food safety mitigation in feedlot cattle due to its antagonistic effects against human foodborne pathogens such as Salmonella and Escherichia coli O157:H7. NP51 not only promotes overall gut health but interferes with the ability of these pathogens to colonize the gastrointestinal tract of cattle. As a result, NP51 reduces fecal shedding of Salmonella and E. coli O157:H7 in cattle presented for harvest and the load of these pathogens that enter the human food chain. Cattle are administered a high dose (1 × 109 CFU/head/day) of NP51 to reduce fecal shedding of foodborne pathogens. Ensiled animal feedstuffs naturally contain a high load of lactic acid bacteria (LAB) and it is not possible to detect and quantify the level of a specific LAB strain (e.g., NP51) in this matrix using traditional microbiological culture. The purpose of this study was to develop a molecular method to detect and quantify viable populations of a specific LAB strain (e.g., NP51) in cattle feedstuffs. The NP51 whole genome sequence was aligned with closely related LAB clustering within the same well-supported clade in a LAB phylogeny derived from 30 conserved amino acid encoding sequence to identify orthologs. A sequence encoding recombinational DNA repair protein RecT was found to be unique to NP51 and used to design primers and a probe for molecular detection and quantification of NP51. The primers and probe were confirmed to be specific to NP51 in vitro. Total RNA was extracted from silage samples, including samples naturally inoculated in the field and control samples that were artificially spiked with a range of NP51 concentrations in the laboratory. Reverse-transcriptase quantitative real-time (RT-qRTi) PCR was used to quantify cDNA copies in samples and cycle threshold (Ct) values were compared to a standard curve to estimate NP51 concentrations. Our results indicate this novel molecular method is suitable to confirm the presence and estimate the concentration of a specific LAB strain in animal feedstuffs containing high background levels of LAB.
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Affiliation(s)
- D I Ayala
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - J C Chen
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - M Bugarel
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - G H Loneragan
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - H C den Bakker
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - K R Kottapalli
- Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX 79409, USA
| | - M M Brashears
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA
| | - K K Nightingale
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Lubbock, Texas Tech University, Box 42141, Lubbock, TX 79409, USA.
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Elder JR, Bugarel M, den Bakker HC, Loneragan GH, Nightingale KK. Interrogation of single nucleotide polymorphisms in gnd provides a novel method for molecular serogrouping of clinically important Shiga toxin producing Escherichia coli (STEC) targeted by regulation in the United States, including the "big six" non-O157 STEC and STEC O157. J Microbiol Methods 2016; 129:85-93. [PMID: 27432340 DOI: 10.1016/j.mimet.2016.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 12/22/2022]
Abstract
Escherichia coli O157:H7 has frequently been associated with foodborne infections and is considered an adulterant in raw non-intact beef in the U.S. Shiga toxin-producing E. coli (STEC) belonging to serogroups O26, O45, O103, O111, O121, and O145 (known as the "big six" non-O157) were estimated to cause >70% of foodborne infections attributed to non-O157 serogroups in the U.S., as a result, these six serogroups have also been targeted by regulation in the U.S. The purpose of this study was to develop a rapid and high-throughput molecular method to group STEC isolates into seven clinically important serogroups (i.e., O157 and the "big six" non-O157 serogroups) targeted by regulation in the U.S. by interrogating single nucleotide polymorphisms (SNPs) in gnd. A collection of 195 STEC isolates, including isolates belonging to O157:H7 (n=18), O26 (n=21), O45 (n=19), O103 (n=24), O111 (n=24), O121 (n=23), O145 (n=21), and ten other STEC serogroups (n=45), was assembled and characterized by full gnd sequencing to identify informative SNPs for molecular serogrouping. A multiplex SNP typing assay was developed to interrogate twelve informative gnd SNPs by single base pair extension chemistry and used to characterize the STEC isolate collection assembled here. SNP types were assigned to each isolate by the assay and polymorphisms were confirmed with gnd sequence data. O-serogroup-specific SNP types were identified for each of the seven clinically important STEC serogroups, which allowed the differentiation of these seven STEC serogroups from other non-O157 STEC serogroups. Although serogroups of the "big six" non-O157 STEC and O157:H7 contained multiple SNP types per O-serogroup, there were no overlapping SNP types between serogroups. Our results demonstrate that molecular serogrouping of STEC isolates by interrogation of informative SNPs in gnd represents an alternative to traditional serogrouping by agglutination for rapid and high-throughput identification of clinically important STEC serogroups targeted by regulation for surveillance and epidemiological investigations.
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Affiliation(s)
- J R Elder
- Department of Food and Animal Sciences, Texas Tech University, Lubbock, TX 79409, United States; Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, United States
| | - M Bugarel
- Department of Food and Animal Sciences, Texas Tech University, Lubbock, TX 79409, United States
| | - H C den Bakker
- Department of Food and Animal Sciences, Texas Tech University, Lubbock, TX 79409, United States; Department of Food Science and Technology, Cornell University, Ithaca, NY 14853, United States
| | - G H Loneragan
- Department of Food and Animal Sciences, Texas Tech University, Lubbock, TX 79409, United States
| | - K K Nightingale
- Department of Food and Animal Sciences, Texas Tech University, Lubbock, TX 79409, United States; Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, United States.
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Webb HE, Bugarel M, den Bakker HC, Nightingale KK, Granier SA, Scott HM, Loneragan GH. Carbapenem-Resistant Bacteria Recovered from Faeces of Dairy Cattle in the High Plains Region of the USA. PLoS One 2016; 11:e0147363. [PMID: 26824353 PMCID: PMC4732617 DOI: 10.1371/journal.pone.0147363] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/04/2016] [Indexed: 01/25/2023] Open
Abstract
Objective A study was conducted to recover carbapenem-resistant bacteria from the faeces of dairy cattle and identify the underlying genetic mechanisms associated with reduced phenotypic susceptibility to carbapenems. Methods One hundred and fifty-nine faecal samples from dairy cattle were screened for carbapenem-resistant bacteria. Phenotypic screening was conducted on two media containing ertapenem. The isolates from the screening step were characterised via disk diffusion, Modified Hodge, and Carba NP assays. Carbapenem-resistant bacteria and carbapenemase-producing isolates were subjected to Gram staining and biochemical testing to include Gram-negative bacilli. Whole genome sequencing was performed on bacteria that exhibited either a carbapenemase-producing phenotype or were not susceptible to ertapenem and were presumptively Enterobacteriaceae. Results Of 323 isolates collected from the screening media, 28 were selected for WGS; 21 of which were based on a carbapenemase-producing phenotype and 7 were presumptively Enterobacteriaceae and not susceptible to ertapenem. Based on analysis of WGS data, isolates included: 3 Escherichia coli harbouring blaCMY-2 and truncated ompF genes; 8 Aeromonas harbouring blacphA-like genes; 1 Acinetobacter baumannii harbouring a novel blaOXA gene (blaOXA-497); and 6 Pseudomonas with conserved domains of various carbapenemase-producing genes. Conclusions Carbapenem resistant bacteria appear to be rare in cattle. Nonetheless, carbapenem-resistant bacteria were detected across various genera and were found to harbour a variety of mechanisms conferring reduced susceptibility. The development and dissemination of carbapenem-resistant bacteria in livestock would have grave implications for therapeutic treatment options in human medicine; thus, continued monitoring of carbapenem susceptibility among enteric bacteria of livestock is warranted.
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Affiliation(s)
- Hattie E. Webb
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Marie Bugarel
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Henk C. den Bakker
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Kendra K. Nightingale
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Sophie A. Granier
- Antimicrobial Resistance Unit, Laboratory for Food Safety, ANSES, Paris-Est University, Maisons-Alfort Cedex, France
| | - H. Morgan Scott
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Guy H. Loneragan
- International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, United States of America
- * E-mail:
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Ison SA, Delannoy S, Bugarel M, Nagaraja TG, Renter DG, den Bakker HC, Nightingale KK, Fach P, Loneragan GH. Targeted Amplicon Sequencing for Single-Nucleotide-Polymorphism Genotyping of Attaching and Effacing Escherichia coli O26:H11 Cattle Strains via a High-Throughput Library Preparation Technique. Appl Environ Microbiol 2016; 82:640-9. [PMID: 26567298 PMCID: PMC4711113 DOI: 10.1128/aem.03182-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 11/04/2015] [Indexed: 12/31/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O26:H11, a serotype within Shiga toxin-producing E. coli (STEC) that causes severe human disease, has been considered to have evolved from attaching and effacing E. coli (AEEC) O26:H11 through the acquisition of a Shiga toxin-encoding gene. Targeted amplicon sequencing using next-generation sequencing technology of 48 phylogenetically informative single-nucleotide polymorphisms (SNPs) and three SNPs differentiating Shiga toxin-positive (stx-positive) strains from Shiga toxin-negative (stx-negative) strains were used to infer the phylogenetic relationships of 178 E. coli O26:H11 strains (6 stx-positive strains and 172 stx-negative AEEC strains) from cattle feces to 7 publically available genomes of human clinical strains. The AEEC cattle strains displayed synonymous SNP genotypes with stx2-positive sequence type 29 (ST29) human O26:H11 strains, while stx1 ST21 human and cattle strains clustered separately, demonstrating the close phylogenetic relatedness of these Shiga toxin-negative AEEC cattle strains and human clinical strains. With the exception of seven stx-negative strains, five of which contained espK, three stx-related SNPs differentiated the STEC strains from non-STEC strains, supporting the hypothesis that these AEEC cattle strains could serve as a potential reservoir for new or existing pathogenic human strains. Our results support the idea that targeted amplicon sequencing for SNP genotyping expedites strain identification and genetic characterization of E. coli O26:H11, which is important for food safety and public health.
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Affiliation(s)
- Sarah A Ison
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA
| | - Sabine Delannoy
- ANSES Food Safety Laboratory, Platform IdentyPath, Université Paris-Est, Maisons-Alfort, France
| | - Marie Bugarel
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA
| | - Tiruvoor G Nagaraja
- Department of Diagnostic Medicine Pathobiology, Kansas State University, Manhattan, Kansas, USA
| | - David G Renter
- Department of Diagnostic Medicine Pathobiology, Kansas State University, Manhattan, Kansas, USA
| | - Henk C den Bakker
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA
| | - Kendra K Nightingale
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA
| | - Patrick Fach
- ANSES Food Safety Laboratory, Platform IdentyPath, Université Paris-Est, Maisons-Alfort, France
| | - Guy H Loneragan
- Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA
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Ison SA, Delannoy S, Bugarel M, Nightingale KK, Webb HE, Renter DG, Nagaraja TG, Loneragan GH, Fach P. Genetic Diversity and Pathogenic Potential of Attaching and Effacing Escherichia coli O26:H11 Strains Recovered from Bovine Feces in the United States. Appl Environ Microbiol 2015; 81:3671-8. [PMID: 25795673 PMCID: PMC4421050 DOI: 10.1128/aem.00397-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 03/15/2015] [Indexed: 12/28/2022] Open
Abstract
Escherichia coli O26 has been identified as the most common non-O157 Shiga toxin-producing E. coli (STEC) serogroup to cause human illnesses in the United States and has been implicated in outbreaks around the world. E. coli has high genomic plasticity, which facilitates the loss or acquisition of virulence genes. Attaching and effacing E. coli (AEEC) O26 strains have frequently been isolated from bovine feces, and there is a need to better characterize the relatedness of these strains to defined molecular pathotypes and to describe the extent of their genetic diversity. High-throughput real-time PCR was used to screen 178 E. coli O26 isolates from a single U.S. cattle feedlot, collected from May to July 2011, for the presence or absence of 25 O26 serogroup-specific and virulence-associated markers. The selected markers were capable of distinguishing these strains into molecularly defined groups (yielding 18 unique marker combinations). Analysis of the clustered regularly interspaced short palindromic repeat 1 (CRISPR1) and CRISPR2a loci further discriminated isolates into 24 CRISPR types. The combination of molecular markers and CRISPR typing provided 20.8% diversity. The recent CRISPR PCR target SP_O26-E, which was previously identified only in stx2-positive O26:H11 human clinical strains, was identified in 96.4% (161/167 [95% confidence interval, 99.2 to 93.6%]) of the stx-negative AEEC O26:H11 bovine fecal strains. This supports that these stx-negative strains may have previously contained a prophage carrying stx or could acquire this prophage, thus possibly giving them the potential to become pathogenic to humans. These results show that investigation of specific genetic markers may further elucidate our understanding of the genetic diversity of AEEC O26 strains in bovine feces.
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Affiliation(s)
- Sarah A Ison
- Texas Tech University, Department of Animal and Food Sciences, Lubbock, Texas, USA
| | - Sabine Delannoy
- French Agency for Food, Environmental and Occupational Health and Safety, Food Safety Laboratory, Platform IdentyPath, Maisons-Alfort, France
| | - Marie Bugarel
- Texas Tech University, Department of Animal and Food Sciences, Lubbock, Texas, USA
| | - Kendra K Nightingale
- Texas Tech University, Department of Animal and Food Sciences, Lubbock, Texas, USA
| | - Hattie E Webb
- Texas Tech University, Department of Animal and Food Sciences, Lubbock, Texas, USA
| | - David G Renter
- Kansas State University, Department of Diagnostic Medicine Pathobiology, Manhattan, Kansas, USA
| | - Tiruvoor G Nagaraja
- Kansas State University, Department of Diagnostic Medicine Pathobiology, Manhattan, Kansas, USA
| | - Guy H Loneragan
- Texas Tech University, Department of Animal and Food Sciences, Lubbock, Texas, USA
| | - Patrick Fach
- French Agency for Food, Environmental and Occupational Health and Safety, Food Safety Laboratory, Platform IdentyPath, Maisons-Alfort, France
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11
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Bugarel M, Vignaud ML, Moury F, Fach P, Brisabois A. Molecular identification in monophasic and nonmotile variants of Salmonella enterica serovar Typhimurium. Microbiologyopen 2012; 1:481-9. [PMID: 23233427 PMCID: PMC3535392 DOI: 10.1002/mbo3.39] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 08/02/2012] [Accepted: 08/08/2012] [Indexed: 12/04/2022] Open
Abstract
Variant strains of Salmonella enterica serovar Typhimurium, lacking one or both flagellar phases have been widely reported. The monophasic S.1,4,[5],12:i:- variant has emerged worldwide in the past few years and has become one of the most frequently encountered in many countries. In contrast, monophasic S.1,4,[5],12:-:1,2 and nonmotile S.1,4,[5],12:-:- strains are rarely described. This study investigated seven molecular markers to identify and delineate monophasic S.1,4,[5],12:i:- (n = 90), S.1,4,[5],12:-:1,2 (n = 25), nonmotile S.1,4,[5],12:-:- (n = 17) strains, and some serovar Typhimurium strains (n = 124) collected through the French Salmonella network between 2001 and 2010. Three markers were commonly detected in serovar Typhimurium and in all variant strains: STM2757, mdh and fliA-B. Monophasic S.1,4,[5],12:i:- were genotypically confirmed by the absence of the fljB, fljA, and hin genes. Nevertheless, 13 (14.5%) of them were positive for these last three genes, revealing monophasic strains named "inconsistent" as previously described. All nonmotile 1,4,[5],12:-:- strains had the fliC, fljA, fljB, and hin genes and the fliC gene was detected in 88% of monophasic S.1,4,[5],12:-:1,2 strains. The combination of the seven markers detection enables to recognize eight different genotypes within the S.1,4,[5],12:i:- collection, among which the Spanish and the U.S. clones previously described could be distinguished and assigned to a genotype. Based on this molecular approach, 71% of the French S.1,4,[5],12:i:- collection belonged to the Spanish clone, whereas only 2% were assigned to the U.S. clone. This study highlights the usefulness of these molecular markers and genotypes for identifying lineages, especially among the epidemiologically important monophasic S.1,4,[5],12:i:- variant.
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Affiliation(s)
- M Bugarel
- French Agency for Food, Environmental and Occupational Health and Health (ANSES), Laboratory for Food Safety, 23 Avenue du Général de Gaulle, 94706, Maisons-Alfort, France
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12
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Bugarel M, Granier S, Bonin E, Vignaud M, Roussel S, Fach P, Brisabois A. Genetic diversity in monophasic (1,4,[5],12:i:- and 1,4,[5],12:-:1,2) and in non-motile (1,4,[5],12:-:-) variants of Salmonella enterica S. Typhimurium. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.06.057] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bugarel M, Granier SA, Weill FX, Fach P, Brisabois A. A multiplex real-time PCR assay targeting virulence and resistance genes in Salmonella enterica serotype Typhimurium. BMC Microbiol 2011; 11:151. [PMID: 21707966 PMCID: PMC3150258 DOI: 10.1186/1471-2180-11-151] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 06/27/2011] [Indexed: 12/02/2022] Open
Abstract
Background Typhimurium is the main serotype of Salmonella enterica subsp. enterica implicated in food-borne diseases worldwide. This study aimed to detect the prevalence of ten markers combined in a macro-array based on multiplex real-time PCR. We targeted characteristic determinants located on pathogenicity islands (SPI-2 to -5, virulence plasmid pSLT and Salmonella genomic island 1 (SGI1)) as well as a specific 16S-23S rRNA intergenic spacer sequence of definitive type 104 (DT104). To investigate antimicrobial resistance, the study also targeted the presence of genes involved in sulfonamide (sul1) and beta-lactam (blaTEM) resistance. Finally, the intI1 determinant encoding integrase from class 1 integron was also investigated. Results A total of 538 unrelated S. Typhimurium strains isolated between 1999 and 2009 from various sources, including food animals, food products, human and environmental samples were studied. Based on the combined presence or absence of these markers, we distinguished 34 different genotypes, including three major genotypes encountered in 75% of the studied strains, Although SPI determinants were almost always detected, SGI1, intI1, sul1 and blaTEM determinants were found 47%, 52%, 54% and 12% of the time respectively, varying according to isolation source. Low-marker patterns were most often detected in poultry sources whereas full-marker patterns were observed in pig, cattle and human sources. Conclusion The GeneDisc® assay developed in this study madeit easier to explore variability within serotype Typhimurium by analyzing ten relevant gene determinants in a large collection of strains. This real-time multiplex method constitutes a valuable tool for strains characterization on epidemiological purposes.
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Affiliation(s)
- Marie Bugarel
- French Agency for Food, Environmental and Occupational Health Safety (ANSES) Laboratory for Food Safety, Maisons-Alfort Cedex, France
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Bugarel M, Martin A, Fach P, Beutin L. Virulence gene profiling of enterohemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli strains: a basis for molecular risk assessment of typical and atypical EPEC strains. BMC Microbiol 2011; 11:142. [PMID: 21689465 PMCID: PMC3133550 DOI: 10.1186/1471-2180-11-142] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 06/21/2011] [Indexed: 11/22/2022] Open
Abstract
Background Enterohaemorrhagic E. coli (EHEC) can cause severe disease such as bloody diarrhoea and haemolytic uraemic syndrome in humans. Besides production of Shiga toxins, the presence of LEE (eae-gene) and non-LEE (nle) encoded effector genes harboured on O-islands OI-122, OI-71 and OI-57 is associated with EHEC virulence and their frequency in outbreaks. Genes encoded by the EHEC-plasmid are putative virulence markers of EHEC. EHEC-plasmids, LEE and non-LEE effector genes have also been detected in some strains of enteropathogenic E. coli (EPEC). The objective of this study was to analyze the relationship between EHEC and EPEC for virulence genes encoded by genomic O-islands and by the EHEC-plasmids. Results Nle genes ent/espL2, nleB and nleE (OI-122), nleA, nleF and nleH1-2 (OI-71), nleG5-2 and nleG6-2 (OI-57), espK (CP-933N) and the EHEC-plasmid encoded genes ehxA, espP, etpD and katP were searched in 73 typical and in 235 atypical enteropathogenic E. coli (EPEC) strains. Typical and atypical EPEC each fall into two clusters. Cluster 1 typical (n = 46) and atypical (n = 129) EPEC strains were characterized by the presence of OI-122 encoded genes and grouped together with 64 investigated EHEC strains. Cluster 2 typical (n = 27) and atypical (n = 106) strains grouped together with 52 LEE-negative, Shiga toxin-producing E. coli (STEC) and with 21 apathogenic E. coli strains. Typical EPEC Cluster 1 strains belonged to serotypes frequently involved in severe illness and outbreaks in children (O111:H2, O114:H2, O55:H6, O127:H6 and O142:H6). Atypical EPEC Cluster 1 strains were characterized by serotypes related to EHEC (O26:H11, O55:H7, O145:H28, O103:H2 and O103:H25). Conclusion The OI-122 encoded nleB gene was found to be most closely associated with Cluster 1 strains and may serve as a diagnostic tool for the identification of virulent EHEC and EPEC seropathotypes. OI-71 encoded genes nleA, nleF and nleH1-2 are less associated with Cluster 1 strains. EHEC-plasmid, OI-57 and CP-933 associated genes showed only weak similarities with virulent Cluster 1 EHEC and EPEC strains.
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Affiliation(s)
- Marie Bugarel
- National Reference Laboratory for Escherichia coli (NRL-E,coli), Federal Institute for Risk Assessment (BfR), Berlin, Germany
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Bugarel M, Beutin L, Martin A, Gill A, Fach P. Micro-array for the identification of Shiga toxin-producing Escherichia coli (STEC) seropathotypes associated with Hemorrhagic Colitis and Hemolytic Uremic Syndrome in humans. Int J Food Microbiol 2010; 142:318-29. [PMID: 20675003 DOI: 10.1016/j.ijfoodmicro.2010.07.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 07/01/2010] [Accepted: 07/10/2010] [Indexed: 11/30/2022]
Abstract
A micro-array has been developed, based on the GeneDisc(R) array, for the genetic identification of 12 O-types and 7 H-types of Shiga toxin-producing Escherichia coli (STEC) including the most clinically relevant enterohemorrhagic E. coli (EHEC) serotypes. The genes selected for determination of the O antigens (rfbE(O157), wzx(O26), wzx(O103), wbd1(O111), ihp1(O145), wzx(O121), wzy(O113), wzy(O91), wzx(O104), wzy(O118), wzx(O45), and wbgN(O55)) and H-types (fliC(H2), fliC(H7), fliC(H8), fliC(H11), fliC(H19), fliC(H21), and fliC(H28)) showed a high specificity and concordance with serology. The micro-array also had a high specificity for EHEC-associated virulence factors, including Shiga toxins 1 and 2 (stx1 and stx2), intimin (eae), enterohemolysin (ehxA), serine protease (espP), catalase peroxidase (katP), the type II secretion system (etpD), subtilase cytotoxin (subA), autoagglutinating adhesin (Saa) and type III secreted effectors encoded in the genomic islands OI-122 (ent/espL2, nleB, and nleE) and OI-71 (nleF, nleH1-2, and nleA). The eae gene was detected in all typical EHEC strains, and the pattern of nle genes encoded in OI-71 and OI-122 was found to be closely associated with certain serotypes of typical EHEC and emerging EHEC strains. Virulence plasmid associated genes such as katP, espP, and etpD were more common in EHEC than in STEC strains; this supports their association with virulence. This array constitutes a valuable approach for the identification of STEC strains with a high potential for human virulence.
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Affiliation(s)
- Marie Bugarel
- AFSSA (French Food Safety Agency), Laboratory for Study and Research on Food Quality and Processes (LERQAP), 23 Av du Général De Gaulle, Fr-94706 Maisons-Alfort, France
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Le Bourgeois P, Bugarel M, Campo N, Daveran-Mingot ML, Labonté J, Lanfranchi D, Lautier T, Pagès C, Ritzenthaler P. The unconventional Xer recombination machinery of Streptococci/Lactococci. PLoS Genet 2008; 3:e117. [PMID: 17630835 PMCID: PMC1914069 DOI: 10.1371/journal.pgen.0030117] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 06/04/2007] [Indexed: 11/19/2022] Open
Abstract
Homologous recombination between circular sister chromosomes during DNA replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. In Escherichia coli, dimer resolution is achieved by site-specific recombination, Xer recombination, involving two paralogous tyrosine recombinases, XerC and XerD, and a 28-bp recombination site (dif) located at the junction of the two replication arms. Xer recombination is tightly controlled by the septal protein FtsK. XerCD recombinases and FtsK are found on most sequenced eubacterial genomes, suggesting that the Xer recombination system as described in E. coli is highly conserved among prokaryotes. We show here that Streptococci and Lactococci carry an alternative Xer recombination machinery, organized in a single recombination module. This corresponds to an atypical 31-bp recombination site (difSL) associated with a dedicated tyrosine recombinase (XerS). In contrast to the E. coli Xer system, only a single recombinase is required to recombine difSL, suggesting a different mechanism in the recombination process. Despite this important difference, XerS can only perform efficient recombination when difSL sites are located on chromosome dimers. Moreover, the XerS/difSL recombination requires the streptococcal protein FtsKSL, probably without the need for direct protein-protein interaction, which we demonstrated to be located at the division septum of Lactococcus lactis. Acquisition of the XerS recombination module can be considered as a landmark of the separation of Streptococci/Lactococci from other firmicutes and support the view that Xer recombination is a conserved cellular function in bacteria, but that can be achieved by functional analogs. In bacteria, genetic information is mainly carried by a single circular chromosome. The replication of this circular molecule sometimes leads to the formation of a chromosome dimer unable to segregate in the daughter cells during the division process. In the bacterial model E. coli, chromosome dimers are resolved in monomers by site-specific recombination: two recombinases (XerC and XerD) cooperatively catalyze the recombination at a chromosomal site (dif), located at the junction of the two replication arms. This recombination is intimately coupled to cell division by the control of the septal protein FtsK. Xer recombination machinery as described in E. coli appears highly conserved among bacterial species. We show by comparative genomics and genetic studies that Streptococci use an alternative Xer recombination system, renamed XerS/difSL, which is composed of a single recombinase phylogenetically unrelated to XerCD proteins and a noncanonical dif site. We also demonstrate that the streptococcal FtsK protein localizes at the division septum and operates the XerS/difSL recombination. This is the first identification of an alternative Xer recombination system in prokaryotes to out knowledge, which might indicate that other unusual chromosome dimer resolution systems could exist in bacterial phyla where a canonical dif site is not detected.
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Affiliation(s)
- Pascal Le Bourgeois
- Laboratoire de Microbiologie et Génétique Microbienne, CNRS, Université Paul Sabatier, Toulouse, France.
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