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Zhang X, Payne M, Kaur S, Lan R. Improved Genomic Identification, Clustering, and Serotyping of Shiga Toxin-Producing Escherichia coli Using Cluster/Serotype-Specific Gene Markers. Front Cell Infect Microbiol 2022; 11:772574. [PMID: 35083165 PMCID: PMC8785982 DOI: 10.3389/fcimb.2021.772574] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 12/03/2021] [Indexed: 11/16/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) have more than 470 serotypes. The well-known STEC O157:H7 serotype is a leading cause of STEC infections in humans. However, the incidence of non-O157:H7 STEC serotypes associated with foodborne outbreaks and human infections has increased in recent years. Current detection and serotyping assays are focusing on O157 and top six (“Big six”) non-O157 STEC serogroups. In this study, we performed phylogenetic analysis of nearly 41,000 publicly available STEC genomes representing 460 different STEC serotypes and identified 19 major and 229 minor STEC clusters. STEC cluster-specific gene markers were then identified through comparative genomic analysis. We further identified serotype-specific gene markers for the top 10 most frequent non-O157:H7 STEC serotypes. The cluster or serotype specific gene markers had 99.54% accuracy and more than 97.25% specificity when tested using 38,534 STEC and 14,216 non-STEC E. coli genomes, respectively. In addition, we developed a freely available in silico serotyping pipeline named STECFinder that combined these robust gene markers with established E. coli serotype specific O and H antigen genes and stx genes for accurate identification, cluster determination and serotyping of STEC. STECFinder can assign 99.85% and 99.83% of 38,534 STEC isolates to STEC clusters using assembled genomes and Illumina reads respectively and can simultaneously predict stx subtypes and STEC serotypes. Using shotgun metagenomic sequencing reads of STEC spiked food samples from a published study, we demonstrated that STECFinder can detect the spiked STEC serotypes, accurately. The cluster/serotype-specific gene markers could also be adapted for culture independent typing, facilitating rapid STEC typing. STECFinder is available as an installable package (https://github.com/LanLab/STECFinder) and will be useful for in silico STEC cluster identification and serotyping using genome data.
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Affiliation(s)
- Xiaomei Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Michael Payne
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Sandeep Kaur
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
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2
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Gutiérrez S, Díaz L, Reyes-Jara A, Yang X, Meng J, González-Escalona N, Toro M. Whole-Genome Phylogenetic Analysis Reveals a Wide Diversity of Non-O157 STEC Isolated From Ground Beef and Cattle Feces. Front Microbiol 2021; 11:622663. [PMID: 33584592 PMCID: PMC7874142 DOI: 10.3389/fmicb.2020.622663] [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: 10/29/2020] [Accepted: 12/17/2020] [Indexed: 11/30/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) causes foodborne outbreaks that can lead to complications such as hemolytic uremic syndrome. Their main reservoir is cattle, and ground beef has been frequently associated with disease and outbreaks. In this study, we attempted to understand the genetic relationship among STEC isolated in Chile from different sources, their relationship to STEC from the rest of the world, and to identify molecular markers of Chilean STEC. We sequenced 62 STEC isolated in Chile using MiSeq Illumina. In silico typing was determined using tools of the Center Genomic Epidemiology, Denmark University (CGE/DTU). Genomes of our local STEC collection were compared with 113 STEC isolated worldwide through a core genome MLST (cgMLST) approach, and we also searched for distinct genes to be used as molecular markers of Chilean isolates. Genomes in our local collection were grouped based on serogroup and sequence type, and clusters were formed within local STEC. In the worldwide STEC analysis, Chilean STEC did not cluster with genomes of the rest of the world suggesting that they are not phylogenetically related to previously described STEC. The pangenome of our STEC collection was 11,650 genes, but we did not identify distinct molecular markers of local STEC. Our results showed that there may be local emerging STEC with unique features, nevertheless, no molecular markers were detected. Therefore, there might be elements such as a syntenic organization that might explain differential clustering detected between local and worldwide STEC.
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Affiliation(s)
- Sebastián Gutiérrez
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Macul, Santiago, Chile
| | - Leonela Díaz
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Macul, Santiago, Chile
| | - Angélica Reyes-Jara
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Macul, Santiago, Chile
| | - Xun Yang
- Department of Nutrition and Food Science, University of Maryland, College Park, College Park, MD, United States
| | - Jianghong Meng
- Department of Nutrition and Food Science, University of Maryland, College Park, College Park, MD, United States.,Joint Institute for Food Safety and Applied Nutrition, University of Maryland, College Park, College Park, MD, United States
| | - Narjol González-Escalona
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD, United States
| | - Magaly Toro
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Macul, Santiago, Chile
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3
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Nojoomi F, Ghasemian A. The relation of phylogroups, serogroups, virulence factors and resistance pattern of Escherichia coli isolated from children with septicemia. New Microbes New Infect 2019; 29:100517. [PMID: 31080621 PMCID: PMC6501060 DOI: 10.1016/j.nmni.2019.100517] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/02/2019] [Accepted: 02/04/2019] [Indexed: 11/30/2022] Open
Abstract
The characterization of virulent and drug-resistant Escherichia coli strains helps to control and provide more accurate information regarding infection and eradication. The aim of this study was to determine the relationship between antibiotic susceptibility, phylogroups and virulence factors of E. coli isolates from children with septicaemia. One hundred dereplicated E. coli isolates were collected from paediatric patients with septicaemia in five hospitals in Tehran (May 2015 to May 2018). The antibiotic susceptibility of isolates was performed as per the 2016 guidelines of the Clinical and Laboratory Standards Institute. Extended-spectrum β-lactamases and carbapenemase genes, phylogroups, serogroups and virulence encoding genes were detected by PCR. Phylogroup B2 was dominant (40%) among strains, followed by phylogroups D (30%), A (8%) and B1 (7%). CTX-M1 was significantly higher in the B2 group (n = 21, p 0.001). Furthermore, the virulence genes iutA (n = 27, p 0.002), csgA (n = 39, p <0.001), kpsMII (n = 39, p 0.002), ibeA (n = 4, p 0.004), vat (n = 5, p 0.003), traT (n = 24, p <0.001), sat (n = 12, p 0.001) and hlyA (n = 33, p <0.001) showed significantly higher rates in phylogroup B2. Three O25/CTXM1/OXA-48 and cnf, iutA, csgA and traT positive isolates belonged to phylogroup B2. Pulsed-field gel electrophoresis analysis showed 85% similarity among 25% of isolates. More than half of the isolates were multidrug-resistant E. coli. A significant relation was observed among iutA, csgA, kpsMII, ibeA, vat, traT, sat and hlyA genes and phylogroup B2. The characterization of virulent and drug-resistant strains helps control and properly eliminate infections. There was no genetic relation among strains in the pulsed-field gel electrophoresis pattern.
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Affiliation(s)
- F Nojoomi
- Department of Microbiology, Faculty of Medicine, Aja University of Medical Sciences, Tehran, Iran
| | - A Ghasemian
- Department of Microbiology, Faculty of Medicine, Aja University of Medical Sciences, Tehran, Iran
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Kennedy CA, Walsh C, Karczmarczyk M, O'Brien S, Akasheh N, Quirke M, Farrell-Ward S, Buckley T, Fogherty U, Kavanagh K, Parker CT, Sweeney T, Fanning S. Multi-drug resistant Escherichia coli in diarrhoeagenic foals: Pulsotyping, phylotyping, serotyping, antibiotic resistance and virulence profiling. Vet Microbiol 2018; 223:144-152. [PMID: 30173740 DOI: 10.1016/j.vetmic.2018.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/04/2018] [Accepted: 08/04/2018] [Indexed: 01/20/2023]
Abstract
Extraintestinal pathogenic E. coli (ExPEC) possess the ability to cause extraintestinal infections such as urinary tract infections, neonatal meningitis and sepsis. While information is readily available describing pathogenic E. coli populations in food-producing animals, studies in companion/sports animals such as horses are limited. In addition, many antimicrobial agents used in the treatment of equine infections are also utilised in human medicine, potentially contributing to the spread of antibiotic resistance determinants among pathogenic strains. The aim of this study was to phenotypically and genotypically characterise the multidrug resistance and virulence associated with 83 equine E. coli isolates recovered from foals with diarrhoeal disease. Serotyping was performed by both PCR and sequencing. Antibiotic resistance was assessed by disc diffusion. Phylogenetic groups, virulence genes, antibiotic resistance genes and integrons were determined by PCR. Thirty-nine (46%) of the isolates were classified as ExPEC and hence considered to be potentially pathogenic to humans and animals. Identified serogroups O1, O19a, O40, O101 and O153 are among previously reported human clinical ExPEC isolates. Over a quarter of the E. coli were assigned to pathogenic phylogroups B2 (6%) and D (23%). Class 1 and class 2 integrons were detected in 85% of E. coli, revealing their potential to transfer MDR to other pathogenic and non-pathogenic bacteria. With 65% of potentially pathogenic isolates harbouring one or more TEM, SHV and CTX-M-2 group β-lactamases, in addition to the high levels of resistance to fluoroquinolones observed, our findings signal the need for increased attention to companion/sport animal reservoirs as public health threats.
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Affiliation(s)
- C A Kennedy
- UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland
| | - C Walsh
- School of Food Science and Environmental Health, DIT, Cathal Brugha Street, Dublin, D01 HV58, Ireland; UCD-Center for Food Safety, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - M Karczmarczyk
- UCD-Center for Food Safety, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - S O'Brien
- UCD-Center for Food Safety, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - N Akasheh
- Medical Directorate, St. James's Hospital, Dublin 8, Ireland
| | - M Quirke
- School of Food Science and Environmental Health, DIT, Cathal Brugha Street, Dublin, D01 HV58, Ireland
| | - S Farrell-Ward
- UCD-Center for Food Safety, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - T Buckley
- Irish Equine Centre, Johnstown, Naas, Co. Kildare, W91 RH93, Ireland
| | - U Fogherty
- Irish Equine Centre, Johnstown, Naas, Co. Kildare, W91 RH93, Ireland
| | - K Kavanagh
- Irish Equine Centre, Johnstown, Naas, Co. Kildare, W91 RH93, Ireland
| | - C T Parker
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, CA, 94710, USA
| | - T Sweeney
- UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland
| | - S Fanning
- UCD-Center for Food Safety, School of Public Health, Physiotherapy & Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland.
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Abstract
AbstractO-antigens present on the surface ofEscherichia coliprovide antigenic specificity for the strain and are the main components for O-serogroup designation. Serotyping using O-group-specific antisera for the identification ofE. coliO-serogroups has been traditionally the gold-standard for distinguishingE. colistrains. Knowledge of the O-group is important for determining pathogenic lineage, classifyingE. colifor epidemiological studies, for determining virulence, and for tracing outbreaks of diseases and sources of infection. However, serotyping has limitations, as the antisera generated against each specific O-group may cross-react, many strains are non-typeable, and others can autoagglutinate or be rough (lacking an O-antigen). Currently, the nucleotide sequences are available for most of the 187 designatedE. coliO-groups. Public health and other laboratories are considering whole genome sequencing to develop genotypic methods to determine O-groups. These procedures require instrumentation and analysis that may not be accessible and may be cost-prohibitive at this time. In this review, we have identified unique gene sequences within the O-antigen gene clusters and have targeted these genes for identification of O-groups using the polymerase chain reaction. This information can be used to distinguish O-groups by developing other platforms forE. colidiagnostics in the future.
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Newell DG, La Ragione RM. Enterohaemorrhagic and other Shiga toxin-producing Escherichia coli (STEC): Where are we now regarding diagnostics and control strategies? Transbound Emerg Dis 2018; 65 Suppl 1:49-71. [PMID: 29369531 DOI: 10.1111/tbed.12789] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Indexed: 12/24/2022]
Abstract
Escherichia coli comprises a highly diverse group of Gram-negative bacteria and is a common member of the intestinal microflora of humans and animals. Generally, such colonization is asymptomatic; however, some E. coli strains have evolved to become pathogenic and thus cause clinical disease in susceptible hosts. One pathotype, the Shiga toxigenic E. coli (STEC) comprising strains expressing a Shiga-like toxin is an important foodborne pathogen. A subset of STEC are the enterohaemorrhagic E. coli (EHEC), which can cause serious human disease, including haemolytic uraemic syndrome (HUS). The diagnosis of EHEC infections and the surveillance of STEC in the food chain and the environment require accurate, cost-effective and timely tests. In this review, we describe and evaluate tests now in routine use, as well as upcoming test technologies for pathogen detection, including loop-mediated isothermal amplification (LAMP) and whole-genome sequencing (WGS). We have considered the need for improved diagnostic tools in current strategies for the control and prevention of these pathogens in humans, the food chain and the environment. We conclude that although significant progress has been made, STEC still remains an important zoonotic issue worldwide. Substantial reductions in the public health burden due to this infection will require a multipronged approach, including ongoing surveillance with high-resolution diagnostic techniques currently being developed and integrated into the routine investigations of public health laboratories. However, additional research requirements may be needed before such high-resolution diagnostic tools can be used to enable the development of appropriate interventions, such as vaccines and decontamination strategies.
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Affiliation(s)
- D G Newell
- Department of Pathology and Infectious Diseases, Faculty of Health and Medical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | - R M La Ragione
- Department of Pathology and Infectious Diseases, Faculty of Health and Medical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, UK
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7
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Castro VS, Carvalho RCT, Conte-Junior CA, Figuiredo EES. Shiga-toxin ProducingEscherichia coli: Pathogenicity, Supershedding, Diagnostic Methods, Occurrence, and Foodborne Outbreaks. Compr Rev Food Sci Food Saf 2017; 16:1269-1280. [DOI: 10.1111/1541-4337.12302] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 08/09/2017] [Accepted: 08/11/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Vinicius Silva Castro
- Animal Science Program, Faculdade de Agronomia e Zootecnia; Univ. Federal de Mato Grosso; 78060-900 Mato Grosso Brazil
- Natl. Inst. of Health Quality Control; Fundação Oswaldo Cruz; Rio de Janeiro 21040-900 Rio de Janeiro Brazil
| | - Ricardo César Tavares Carvalho
- Nutrition, Food and Metabolism Program, Faculdade de Nutrição; Univ. Federal de Mato Grosso; 78060-900 Mato Grosso Brazil
| | - Carlos Adam Conte-Junior
- Dept. of Food Technology, Faculdade de Veterinária; Univ. Federal Fluminense; 24230-340 Rio de Janeiro Brazil
- Food Science Program, Inst. de Química; Univ. Federal do Rio de Janeiro; 21941-909 Rio de Janeiro Brazil
- Natl. Inst. of Health Quality Control; Fundação Oswaldo Cruz; Rio de Janeiro 21040-900 Rio de Janeiro Brazil
| | - Eduardo Eustáquio Souza Figuiredo
- Animal Science Program, Faculdade de Agronomia e Zootecnia; Univ. Federal de Mato Grosso; 78060-900 Mato Grosso Brazil
- Nutrition, Food and Metabolism Program, Faculdade de Nutrição; Univ. Federal de Mato Grosso; 78060-900 Mato Grosso Brazil
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8
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Ranjbar R, Sheikhshahrokh A, Jonaidi Jafari N. Shiga (vero) toxin producingEscherichia coliin various types of food stuffs; virulence factors, O-serogroups and antimicrobial resistance properties. J Food Saf 2016. [DOI: 10.1111/jfs.12312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Reza Ranjbar
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences; Tehran Iran
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9
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Baker CA, Park SH, Kim SA, Rubinelli PM, Roto SM, Lee SI, Ramsaroop S, Miller M, Ricke SC. Formalin-fixed cells as an internal standard approach for the detection and quantitative assessment of Shiga toxin-producing Escherichia coli (STEC). Food Control 2016. [DOI: 10.1016/j.foodcont.2015.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Verhaegen B, Van Damme I, Heyndrickx M, Botteldoorn N, Elhadidy M, Verstraete K, Dierick K, Denayer S, De Zutter L, De Reu K. Evaluation of detection methods for non-O157 Shiga toxin-producing Escherichia coli from food. Int J Food Microbiol 2016; 219:64-70. [PMID: 26736066 DOI: 10.1016/j.ijfoodmicro.2015.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 01/09/2023]
Abstract
Shiga toxin-producing Escherichia coli (STEC) remains a major foodborne pathogen of concern across the globe. Rapid detection and isolation of this pathogen is of great importance for public health reasons. In this study the detection and isolation of four non-O157 STEC strains (O26, O103, O111, O145) from different artificially contaminated matrices, namely ground (minced) beef, cattle carcass swab, lettuce mix and sprouted soy beans, were evaluated. Low amounts of STEC were used (0.25-1.40 cfu/g) to spike the samples. All samples were enriched in parallel in Buffered Peptone Water (BPW) and Brila broth. After enrichment, detection was performed using real-time PCR (qPCR), and isolation using two chromogenic agar media, CHROMagar™ STEC and ChromID™ EHEC. Inoculation on the agar media was performed either directly after enrichment or after the use of an acid treatment procedure. Furthermore, the use of this procedure was also tested on naturally contaminated food products, using 150 stx-positive samples. Although the qPCR Cycle Threshold (Ct) values were lower after enrichment in Brila broth, no significant differences in recovery were observed between both enrichment broths. Both agar media were equally suitable for the isolation of STEC, although a significantly higher recovery was obtained when using both agar media in parallel. For samples with a Ct value above 25, an acid treatment step prior to isolation ensured a significant improvement in the recovery of STEC due to the reduction in background microbiota. This acid treatment procedure proved especially useful for the isolation of STEC from sprouted soy bean samples.
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Affiliation(s)
- Bavo Verhaegen
- Institute for Agriculture and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium; Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Inge Van Damme
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Marc Heyndrickx
- Institute for Agriculture and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium; Ghent University, Faculty of Veterinary Medicine, Department of Pathology, Bacteriology and Poultry Diseases, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Nadine Botteldoorn
- Foodborne Pathogens, Scientific Institute of Public Health, Juliettte Wytsmanstraat 14, 1050 Brussels, Belgium
| | - Mohamed Elhadidy
- Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Karen Verstraete
- Institute for Agriculture and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium
| | - Katelijne Dierick
- Foodborne Pathogens, Scientific Institute of Public Health, Juliettte Wytsmanstraat 14, 1050 Brussels, Belgium
| | - Sarah Denayer
- Foodborne Pathogens, Scientific Institute of Public Health, Juliettte Wytsmanstraat 14, 1050 Brussels, Belgium
| | - Lieven De Zutter
- Ghent University, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Koen De Reu
- Institute for Agriculture and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium.
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Shahrani M, Dehkordi FS, Momtaz H. Characterization of Escherichia coli virulence genes, pathotypes and antibiotic resistance properties in diarrheic calves in Iran. Biol Res 2014; 47:28. [PMID: 25052999 PMCID: PMC4105491 DOI: 10.1186/0717-6287-47-28] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/05/2014] [Indexed: 01/07/2023] Open
Abstract
Background Calf diarrhea is a major economic concern in bovine industry all around the world. This study was carried out in order to investigate distribution of virulence genes, pathotypes, serogroups and antibiotic resistance properties of Escherichia coli isolated from diarrheic calves. Results Totally, 76.45% of 824 diarrheic fecal samples collected from Isfahan, Chaharmahal, Fars and Khuzestan provinces, Iran were positive for E. coli and all of them were also positive for cnf2, hlyA, cdtIII, f17c, lt, st, stx1, eae, ehly, stx2 and cnf1 virulence genes. Chaharmahal had the highest prevalence of STEC (84.61%), while Isfahan had the lowest (71.95%). E. coli serogroups had the highest frequency in 1–7 days old calves and winter season. Distribution of ETEC, EHEC, AEEC and NTEC pathotypes among E. coli isolates were 28.41%, 5.07%, 29.52% and 3.49%, respectively. Statistical analyses were significant for presence of bacteria between various seasons and ages. All isolates had the high resistance to penicillin (100%), streptomycin (98.25%) and tetracycline (98.09%) antibiotics. The most commonly detected resistance genes were aadA1, sul1, aac[3]-IV, CITM, and dfrA1. The most prevalent serogroup among STEC was O26. Conclusions Our findings should raise awareness about antibiotic resistance in diarrheic calves in Iran. Clinicians should exercise caution when prescribing antibiotics.
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12
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Juneja VK, Mukhopadhyay S, Ukuku D, Hwang CA, Wu VCH, Thippareddi H. Interactive effects of temperature, pH, and water activity on the growth kinetics of Shiga toxin-producing Escherichia coli O104:H4 3. J Food Prot 2014; 77:706-12. [PMID: 25198132 DOI: 10.4315/0362-028x.jfp-13-387] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The risk of non-O157 Shiga toxin-producing Escherichia coli strains has become a growing public health concern. Several studies characterized the behavior of E. coli O157:H7; however, no reports on the influence of multiple factors on E. coli O104:H4 are available. This study examined the effects and interactions of temperature (7 to 46°C), pH (4.5 to 8.5), and water activity (aw ; 0.95 to 0.99) on the growth kinetics of E. coli O104:H4 and developed predictive models to estimate its growth potential in foods. Growth kinetics studies for each of the 23 variable combinations from a central composite design were performed. Growth data were used to obtain the lag phase duration (LPD), exponential growth rate, generation time, and maximum population density (MPD). These growth parameters as a function of temperature, pH, and aw as controlling factors were analyzed to generate second-order response surface models. The results indicate that the observed MPD was dependent on the pH, aw, and temperature of the growth medium. Increasing temperature resulted in a concomitant decrease in LPD. Regression analysis suggests that temperature, pH, and aw significantly affect the LPD, exponential growth rate, generation time, and MPD of E. coli O104:H4. A comparison between the observed values and those of E. coli O157:H7 predictions obtained by using the U. S. Department of Agriculture Pathogen Modeling Program indicated that E. coli O104:H4 grows faster than E. coli O157:H7. The developed models were validated with alfalfa and broccoli sprouts. These models will provide risk assessors and food safety managers a rapid means of estimating the likelihood that the pathogen, if present, would grow in response to the interaction of the three variables assessed.
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13
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Dehkordi FS, Yazdani F, Mozafari J, Valizadeh Y. Virulence factors, serogroups and antimicrobial resistance properties of Escherichia coli strains in fermented dairy products. BMC Res Notes 2014; 7:217. [PMID: 24708594 PMCID: PMC3983858 DOI: 10.1186/1756-0500-7-217] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 03/27/2014] [Indexed: 01/13/2023] Open
Abstract
Background From a clinical perspective, it is essential to know the microbial safety of fermented dairy products. Doogh and kashk are fermented dairies. These products are used by millions of people but their microbial qualities are unknown. Shiga toxin producing Escherichia coli (STEC) is one of the most commonly detected pathogens in the cases of food poisoning and food-borne illnesses. The present investigation was carried out in order to study the molecular characterization and antimicrobial resistance properties of STEC strains isolated from fermented dairy products. Methods Six hundred fermented dairy samples were collected and immediately transferred to the laboratory. All samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of O157 , O26, O103, O111, O145, O45, O91, O113, O121 and O128 STEC serogroups, tetA, tetB, blaSHV, CITM, cmlA, cat1, aadA1, dfrA1, qnr, aac (3)-IV, sul1 and ereA antibiotic resistance genes and stx1, stx2, eaeA, ehly, cnf1, cnf2, iutA, cdtB, papA, traT, sfaS and fyuA virulence factors using PCR. Antimicrobial susceptibility testing was performed also using disk diffusion methodology with Mueller–Hinton agar. Results Fifty out of 600 (8.33%) dairy samples harbored E. coli. In addition, yoghurt was the most commonly contaminated dairy. O157 (26%) and O26 (12%) were the most commonly detected serogroups. A significant difference was found between the frequency of Attaching and Effacing E. coli and Enterohaemorrhagic E. coli (P <0.05). Stx1 (44%), eae (36%), papA (32%) stx2 (30%), and ehly (28%) were the most commonly detected virulence factors. The genes encode resistance against tetracycline (tetA and tetB) (76% and 70%, respectively), cephalothin (blaSHV) (38%), ampicillin (CITM) (36%) and gentamicin (aac (3)-IV) (32%) were the most commonly detected. High resistance levels to tetracycline (84%), penicillin (46%), ampicillin (38%) and streptomycin (36%) were observed. Conclusion Fermented dairy products can easily become contaminated by antibiotic resistant STEC strains. Our findings should raise awareness about antibiotic resistance in Iran. Clinicians should exercise caution when prescribing antibiotics, especially in veterinary treatments.
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Affiliation(s)
- Farhad Safarpoor Dehkordi
- Young Researchers Club and Elite, ShahreKord Branch, Islamic Azad University, P,O, Box 166, ShahreKord, Iran.
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Verstraete K, Van Coillie E, Werbrouck H, Van Weyenberg S, Herman L, Del-Favero J, De Rijk P, De Zutter L, Joris MA, Heyndrickx M, De Reu K. A qPCR assay to detect and quantify Shiga toxin-producing E. coli (STEC) in cattle and on farms: a potential predictive tool for STEC culture-positive farms. Toxins (Basel) 2014; 6:1201-21. [PMID: 24681714 PMCID: PMC4014729 DOI: 10.3390/toxins6041201] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/03/2014] [Accepted: 03/11/2014] [Indexed: 11/16/2022] Open
Abstract
Shiga toxin-producing E. coli (STEC), of various serogroups harboring the intimin gene, form a serious threat to human health. They are asymptomatically carried by cattle. In this study, a quantitative real-time PCR (qPCR) method was developed as a molecular method to detect and quantify Shiga toxin genes stx1 and stx2 and the intimin gene eae. Subsequently, 59 fecal samples from six farms were tested using qPCR and a culture method as a reference. Three farms had contaminated animals as demonstrated by the culture method. Culture-positive farms showed moderate significantly higher stx prevalences than culture-negative farms (p = 0.05). This is the first study which showed preliminary results that qPCR can predict STEC farm contamination, with a specificity of 77% and a sensitivity of 83%, as compared with the culture method. Furthermore, the presence or quantity of stx genes in feces was not correlated to the isolation of STEC from the individual animal. Quantitative data thus did not add value to the results. Finally, the detection of both stx and eae genes within the same fecal sample or farm using qPCR was not correlated with the isolation of an eae-harboring STEC strain from the respective sample or farm using the culture method.
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Affiliation(s)
- Karen Verstraete
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Els Van Coillie
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Hadewig Werbrouck
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Stephanie Van Weyenberg
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Lieve Herman
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Jurgen Del-Favero
- Applied Molecular Genomics Group, Department of Molecular Genetics, Flemish Institute for Biotechnology (VIB), Universiteitsplein 1, Antwerpen 2610, Belgium.
| | - Peter De Rijk
- Applied Molecular Genomics Group, Department of Molecular Genetics, Flemish Institute for Biotechnology (VIB), Universiteitsplein 1, Antwerpen 2610, Belgium.
| | - Lieven De Zutter
- Department of Pathology, Bacteriology and Poultry Diseases, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.
| | - Maria-Adelheid Joris
- Department of Pathology, Bacteriology and Poultry Diseases, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.
| | - Marc Heyndrickx
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
| | - Koen De Reu
- Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
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Xu X, Wu Q, Zhang J, Ye Y, Yang X, Dong X. Occurrence and characterization of Cronobacter spp. in powdered formula from Chinese retail markets. Foodborne Pathog Dis 2014; 11:307-12. [PMID: 24437706 DOI: 10.1089/fpd.2013.1657] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cronobacter spp. (formerly known as Enterobacter sakazakii) are foodborne pathogens that cause rare but life-threatening diseases in neonates and infants through consumption of contaminated powdered infant formula. This study was conducted to investigate the occurrence of Cronobacter spp. in powdered formula in China and to further characterize Cronobacter isolates. Isolates were identified to the species level based on the fusA gene sequence, and strains of C. sakazakii were further subtyped by applying the polymerase chain reaction (PCR)-based serotyping method. A total of 23 strains of Cronobacter spp. isolated from 530 powdered formula samples were identified using conventional biochemical methods and duplex PCR. Cronobacter spp. were detected in 6.25%, 1.82%, 3.64%, 5.45%, and 2.50% of the general formula, infant formula (age <6 months), follow-up formula (6-12 months of age), growing-up formula (1-3 years of age), and children's formula (3-6 years of age), respectively. The individual species were identified as C. sakazakii (22 isolates) and C. malonaticus (1 isolate). Among 22 C. sakazakii isolates, representatives of all but two O-antigen serotypes (serotypes O5 and O6) were recognized.
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Affiliation(s)
- Xiaoke Xu
- State Key Laboratory of Applied Microbiology, South China (The Ministry-Province Joint Development), Guangdong Institute of Microbiology , Guangzhou, China
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16
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Momtaz H, Dehkordi FS, Hosseini MJ, Sarshar M, Heidari M. Serogroups, virulence genes and antibiotic resistance in Shiga toxin-producing Escherichia coli isolated from diarrheic and non-diarrheic pediatric patients in Iran. Gut Pathog 2013; 5:39. [PMID: 24330673 PMCID: PMC3866933 DOI: 10.1186/1757-4749-5-39] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 12/09/2013] [Indexed: 01/01/2023] Open
Abstract
Background From a clinical perspective, it is important to know which serogroups, virulence genes and antibiotic resistance patterns are present in Shiga toxin-producing Escherichia coli strains in pediatric patients suffering from diarrheic and non-diarrheic infections. This is the first study in Iran that has comprehensively investigated the Shiga toxin-producing Escherichia coli -related infection characteristics in diarrheic and non-diarrheic pediatric patients of 0–60 months of age. Methods Two-hundred and twenty four diarrheic and 84 non-diarrheic stool specimens were collected from the Baqiyatallah hospital of Tehran, Iran. The stool samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of antibiotic resistance genes and bacterial virulence factors using PCR. Antimicrobial susceptibility testing was performed using disk diffusion method. Results One-hundred and fifty four out of 224 (68.75%) diarrheic stools and 31 out of 84 (36.90%) non-diarrheic stools harbored E. coli. In addition, children in 13–24 month-old age group had the highest incidence of infection with this bacterium (77.63%). A significant difference was found between the frequency of Attaching and Effacing Escherichia coli and Enterohaemorrhagic Escherichia coli (P =0.045). The genes encoding Shiga toxins and intimin were the most commonly detected virulence factors. Among all serogroups studied, O26 (27.04%) and O111 (18.85%) had the highest incidences in the diarrheic and non-diarrheic patients. The incidence of genes encoding resistance against sulfonamide (sul1), gentamicin (aac(3)-IV), trimethoprim (aadA1), cephalothin (blaSHV) and tetracycline (tetA) were 82.78%, 68.03%, 60.65%, 56.55% and 51.63%, respectively. High resistance levels against penicillin (100%), tetracycline (86.88%), gentamicin (62.29%) and streptomycin (54.91%) were observed. Marked seasonality in the serogroup distributions was evident, while STEC infections were more common in summer (P =0.041). Conclusions Our findings should raise awareness about antibiotic resistance in diarrheic pediatric patients in Iran. Clinicians should exercise caution when prescribing antibiotics, especially during the warmer months of the year.
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Affiliation(s)
- Hassan Momtaz
- Department of Microbiology, Shahrekord Branch, Islamic Azad University, P,O, Box 166, Shahrekord, Iran.
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17
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Ozpınar H, Turan B, Tekiner IH, Tezmen G, Gökçe I, Akıneden O. Evaluation of pathogenic Escherichia coli occurrence in vegetable samples from district bazaars in Istanbul using real-time PCR. Lett Appl Microbiol 2013; 57:362-7. [PMID: 23789811 DOI: 10.1111/lam.12122] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 06/09/2013] [Accepted: 06/14/2013] [Indexed: 11/30/2022]
Abstract
UNLABELLED In this study, a total of 180 vegetable samples collected from several district bazaars of Istanbul were investigated for the occurrence of Escherichia coli using a culture-based method. The isolates were subjected to real-time PCR detection of Shiga-toxin-producing E. coli (STEC) using primers specific for the Shiga toxin (stx1 and stx2) and intimin (eae) virulence genes. The prevalences of E. coli in the samples were 93·3% in spinach, 93·3% in lettuce, 86·6% in parsley, 43·3% in carrot, 33·3% in cucumber and 13·3% in tomato. Of 180 samples, 13 contained STEC (six parsley, three carrots, three lettuces and one cucumber of 30 samples of each). Among 13 STEC-positive isolates, presence of stx1, stx2 and eae was detected in only one sample, stx2 and eae in two samples, and stx2 in ten samples. Serotype O157 was found in parsley, lettuce and carrot; O26 in lettuce, parsley, cucumber and carrot; and O111 and O113 in parsley only. In conclusion, STEC was present in vegetable samples marketed in several district bazaars in Istanbul; this might represent a route of transmission of pathogenic STEC to humans and be harmful to public health. SIGNIFICANCE AND IMPACT OF THE STUDY We assessed the occurrence of virulent Escherichia (E.) coli and Shiga-toxin-producing E. coli (STEC) virulent populations in the vegetable samples collected from several district bazaars in Istanbul, Turkey. The results indicated that the vegetables from the bazaars had poor microbial quality and represented a potential health risk to customers.
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Affiliation(s)
- H Ozpınar
- Food Engineering Department of Istanbul Aydın University, Sefaköy-Istanbul, Turkey
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18
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Momtaz H, Jamshidi A. Shiga toxin-producing Escherichia coli isolated from chicken meat in Iran: serogroups, virulence factors, and antimicrobial resistance properties. Poult Sci 2013; 92:1305-13. [PMID: 23571340 DOI: 10.3382/ps.2012-02542] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The aim of the current study was to determine the virulence factors, serogroups, and antibiotic resistance properties of Shiga toxin-producing Escherichia coli isolated from chicken meat samples. A total of 422 chicken meat samples were collected from 5 townships of Iran. Specimens were immediately transferred to the laboratory in a cooler with an ice pack. Samples were cultured, and the positive culture samples were analyzed by PCR assays. Finally, the antimicrobial susceptibility test was performed using the disk diffusion method in Mueller-Hinton agar. According to the results, out of 422 samples, 146 (34.59%) were confirmed to be E. coli positive and among E. coli-positive samples, 51 (34.93%) and 31 (21.23%) were from attaching and effacing E. coli (AEEC) and enterohemorrhagic E. coli (EHEC) subgroups, respectively. All of the EHEC-positive samples had all stx1, eaeA, and ehly virulence genes, whereas only 5 (9.80%) of AEEC subgroup had all stx1, stx2, and eaeA genes. As the data revealed, O157 was the most prevalent and O111 was the least prevalent strains in the Shiga toxin-producing E. coli (STEC) population. Among STEC strains, sulI and blaSHV had the highest and lowest incidence rate, respectively. There was a high resistance to tetracycline (76.82%), followed by chloramphenicol (73.17%) and nitrofurantoin (63.41%), but there was low resistance to cephalotine (7.31%) antibiotics in isolated strains. Results shows that the PCR technique has a high performance for detection of serogroups, virulence genes, and antibiotic resistance genes in STEC strains. This study is the first prevalence report of detection of virulence genes, serogroups, and antibiotic resistance properties of STEC strains isolated from chicken meat samples in Iran. Based on the results, chicken meat is one of the main sources of STEC strains and its virulence factors in Iran, so an accurate meat inspection would reduce disease outbreaks.
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Affiliation(s)
- Hassan Momtaz
- College of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.
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19
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Wang F, Yang Q, Kase JA, Meng J, Clotilde LM, Lin A, Ge B. Current trends in detecting non-O157 Shiga toxin-producing Escherichia coli in food. Foodborne Pathog Dis 2013; 10:665-77. [PMID: 23755895 DOI: 10.1089/fpd.2012.1448] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Non-O157 Shiga toxin-producing Escherichia coli (non-O157 STEC) strains are increasingly recognized as important foodborne pathogens worldwide. Together with E. coli O157:H7, six additional STEC serogroups (O26, O45, O103, O111, O121, and O145) are now regulated as adulterants in certain raw beef products in the United States. However, effective detection and isolation of non-O157 STEC strains from food matrices remain challenging. In the past decade, great attention has been paid to developing rapid and reliable detection methods for STEC in general (targeting common virulence factors) and specific STEC serogroups in particular (targeting serogroup-specific traits). This review summarizes current trends in detecting non-O157 STEC in food, including culture, immunological, and molecular methods, as well as several novel technologies.
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Affiliation(s)
- Fei Wang
- Department of Food Science, Louisiana State University Agricultural Center , Baton Rouge, Louisiana, USA
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20
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Yonekita T, Fujimura T, Morishita N, Matsumoto T, Morimatsu F. Simple, rapid, and reliable detection of Escherichia coli O26 using immunochromatography. J Food Prot 2013; 76:748-54. [PMID: 23643115 DOI: 10.4315/0362-028x.jfp-12-423] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Shiga toxin-producing Escherichia coli (STEC) O26 has been increasingly associated with diarrheal disease all over the world. We developed an immunochromatographic (ic) strip for the rapid detection of E. coli O26 in food samples. To determine the specificity of the IC strip, pure cultures of 67 E. coli and 22 non-E. coli strains were tested with the IC strip. The IC strip could detect all (18 of 18) E. coli O26 strains tested and did not react with strains of any other E. coli serogroup or non-E. coli strains tested (0 of 71). The minimum detection limits for E. coli O26 were 2.2 × 10(3) to 1.0 × 10(5) cfu/ml. To evaluate the ability of the IC strip to detect E. coli O26 in food, 25-g food samples (ground beef, beef liver, ground chicken, alfalfa sprout, radish sprout, spinach, natural cheese, and apple juice) were spiked with E. coli O26. The IC strip was able to detect E. coli O26 at very low levels (approximately 1 cfu/25 g of food samples) after an 18-h enrichment, and the IC strip results were in 100% agreement with the results of the culture method and pcr assay. When 115 meat samples purchased from supermarkets were tested, 5 were positive for E. coli O26 with the IC strip; these results were confirmed with a pcr assay. These results suggest that the IC strip is a useful tool for detecting E. coli O26 in food samples.
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Affiliation(s)
- Taro Yonekita
- R&D Center, Nippon Meat Packers, Inc., 3-3 Midorigahara, Tsukuba, Ibaraki 300-2646, Japan.
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Müller A, Stephan R, Fricker-Feer C, Lehner A. Genetic diversity of Cronobacter sakazakii isolates collected from a Swiss infant formula production facility. J Food Prot 2013; 76:883-7. [PMID: 23643134 DOI: 10.4315/0362-028x.jfp-12-521] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, 141 Cronobacter isolates that were collected based on a hygienic monitoring program performed in a powdered infant formula production facility in Switzerland between September 2011 and October 2012 were further characterized. Isolates were identified to the species level by molecular methods, and strains of Cronobacter sakazakii were further subtyped by applying PCR-based O-antigen serotyping, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). C. sakazakii was the most prevalent species identified (93.6%). Among this collection of isolates, representatives of all but one O-antigen serotype (serotype O5) were recognized. MLST analysis of 19 selected isolates revealed that most of the typeable isolates belonged to sequence type (ST) 4. Correlations between ST4 and serotype O2 and between ST83 and serotype O7 were observed. PFGE analysis revealed clusters with multiple isolates, including strains from samples collected at different time points and sampling sources. Generally, the observed heterogeneity among strains collected over the 13 months of the monitoring program was high, suggesting a constant flux among strains rather than a selection for persisting organisms.
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Affiliation(s)
- Andrea Müller
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Momtaz H, Safarpoor Dehkordi F, Rahimi E, Ezadi H, Arab R. Incidence of Shiga toxin-producing Escherichia coli serogroups in ruminant's meat. Meat Sci 2013; 95:381-8. [PMID: 23747633 DOI: 10.1016/j.meatsci.2013.04.051] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 02/25/2013] [Accepted: 04/16/2013] [Indexed: 12/23/2022]
Abstract
To assess the presences of Escherichia coli, its serogroups, virulence factors and antibiotic resistance properties in ruminant's meat, a total of 820 raw meat samples were collected and then evaluated using culture, PCR and disk diffusion methods. Totally, 238 (29.02%) samples were positive for presence of Escherichia coli. All of the isolates had more than one virulence gene including Stx1, Stx2, eaeA and ehly. All investigated serogroups were found in beef and sheep and all except O145, O121 and O128 were found in goat. The O91, O113, O111, O103, O26 and O157 serogroups were found in camel. Totally, aadA1-blaSHV combination was the most predominant antibiotic resistance gene. The highest resistance of STEC strains was seen against penicillin while resistance to nitrofurantoin and ciprofloxacin was minimal. These findings showed that health care and meat inspection should be reconsidered in Iranian slaughterhouses and butchers.
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Affiliation(s)
- Hassan Momtaz
- Department of Microbiology, College of Veterinary Medicine, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.
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Development of a novel multiplex lateral flow assay using an antimicrobial peptide for the detection of Shiga toxin-producing Escherichia coli. J Microbiol Methods 2013; 93:251-6. [PMID: 23523969 DOI: 10.1016/j.mimet.2013.03.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/01/2013] [Accepted: 03/11/2013] [Indexed: 11/22/2022]
Abstract
The binding capacity of peptides with broad antimicrobial activity, or antimicrobial peptides (AMPs), to microbes has recently been applied to the specific detection of bacteria and viruses. We established a novel lateral flow assay (LFA) that combines AMPs labeled with colloidal gold and a target-specific antibody immobilized on a nitrocellulose membrane. α-Helical AMPs, especially cecropin P1 (CP1), magainin 2 (MG2), and ceratotoxin A (CtxA), were shown to have optimal properties as probes in LFA. We also established a multiplex LFA for the simultaneous detection and identification of three serogroups of Shiga toxin-producing Escherichia coli (STEC) using the CP1 probe with polyclonal antibodies anti-O157, anti-O26, and anti-O111. Each serogroup of E. coli could easily and rapidly be detected by multiplex LFA using CP1 and each was clearly visualized in a different position on the LFA strip. The multiplex LFA could detect all tested E. coli strains from serogroups O157 (22/22), O26 (17/17), and O111 (7/7), and the detection limit was 10(4)CFU/mL. No other serogroups of E. coli, including STEC O45, O91, O103, O121, and O145, or non-E. coli strains, reacted. The multiplex LFA could detect E. coli O157, O26, and O111 in food samples at very low levels (6.3, 2.9, and 5.6 CFU per 25 g of ground beef, respectively) after 18-h enrichment, and these results were in accordance with the results of the culture method, immunochromatography (IC) strip, and PCR. Given the broad binding capacity, AMP probes in combination with specific antibodies in the novel multiplex LFA may have the potential to detect various microbes simultaneously with identification on a single strip.
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Momtaz H, Safarpoor Dehkordi F, Taktaz T, Rezvani A, Yarali S. Shiga toxin-producing Escherichia coli isolated from bovine mastitic milk: serogroups, virulence factors, and antibiotic resistance properties. ScientificWorldJournal 2012; 2012:618709. [PMID: 23213293 PMCID: PMC3507047 DOI: 10.1100/2012/618709] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 10/12/2012] [Indexed: 12/14/2022] Open
Abstract
The aim of this study was to detect the virulence factors, serogroups, and antibiotic resistance properties of Shiga toxin-producing Escherichia coli, by using 268 bovine mastitic milk samples which were diagnosed using California Mastitis Test. After E. coli identification, PCR assays were developed for detection of different virulence genes, serogroups, and antibiotic resistance genes of Escherichia coli. The antibiotic resistance pattern was studied using disk diffusion method. Out of 268 samples, 73 (27.23%) were positive for Escherichia coli, and, out of 73 positive samples, 15 (20.54%) were O26 and 11 (15.06%) were O157 so they were the highest while O111 was not detected in any sample so it was the lowest serogroup. Out of 73 STEC strains, 11 (15.06%) and 36 (49.31%) were EHEC and AEEC, respectively. All of the EHEC strains had stx1, eaeA, and ehly, virulence genes, while in AEEC strains stx1 had the highest prevalence (77.77%), followed by eaeA (55.55%). Totally, aadA1 (65.95%) had the highest while blaSHV (6.38%) had the lowest prevalence of antibiotic resistance genes. The disk diffusion method showed that the STEC strains had the highest resistance to penicillin (100%), followed by tetracycline (57.44%), while resistance to cephalothin (6.38%) was the lowest.
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Affiliation(s)
- Hassan Momtaz
- Department of Microbiology, College of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, P.O. Box 166, Shahrekord, Iran.
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Momtaz H, Farzan R, Rahimi E, Safarpoor Dehkordi F, Souod N. Molecular characterization of Shiga toxin-producing Escherichia coli isolated from ruminant and donkey raw milk samples and traditional dairy products in Iran. ScientificWorldJournal 2012; 2012:231342. [PMID: 22919299 PMCID: PMC3419413 DOI: 10.1100/2012/231342] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Accepted: 07/04/2012] [Indexed: 01/08/2023] Open
Abstract
The aims of the current study were to detect the virulence factors and antibiotic resistance of Shiga toxin-producing E. coli, in animal milk and dairy products in Iran. After E. coli dentification with culture method, PCR assay were developed for detection of pathogenic genes, serotypes and antibiotic resistance genes of E. coli. Results showed that out of 719 samples, 102 (14.18%) were confirmed to be positive for E. coli and out of 102 positive samples, 17.64% were O26 and 13.72% were O157 and 1.96% were O91 and 1.96% were O145 serotypes. Totally, the prevalence of stx1 and papA genes were the highest while the prevalence of sfaS and fyuA were the lowest in the positive samples. PCR results showed that tetA, tetB were the highest (64.70%) and aac(3)-IV were the lowest (27.45%) antibiotic resistant genes in E. coli positive samples. Our study indicated that the isolated E. coli trains in these regions had a highest antibiotic resistance to tetracycline (58.82%) and the lowest to nitrofurantoin (3.92%). tetA gene and E. coli O157 serotype had highest and aac(3)-IV gene, and E. coli O145 serotype had a lowest frequency rates of antibiotics resistance genes, in the region.
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Affiliation(s)
- Hassan Momtaz
- Department of Microbiology, College of Veterinary Medicine, Islamic Azad University, Shahrekord Branch, Shahrekord 166, Iran.
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Predicting the presence of non-O157 Shiga toxin-producing Escherichia coli in ground beef by using molecular tests for Shiga toxins, intimin, and O serogroups. Appl Environ Microbiol 2012; 78:7152-5. [PMID: 22843533 DOI: 10.1128/aem.01508-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When 3,972 ground beef enrichments with 6 confirmed to contain a non-O157 Shiga toxin-producing intimin-positive Escherichia coli isolate were tested for Shiga toxin, intimin, and O group (O26, O45, O103, O111, O121, and O145) genes, 183 potential positives and only 2 of the 6 confirmed positives were identified.
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Association of nucleotide polymorphisms within the O-antigen gene cluster of Escherichia coli O26, O45, O103, O111, O121, and O145 with serogroups and genetic subtypes. Appl Environ Microbiol 2012; 78:6689-703. [PMID: 22798363 DOI: 10.1128/aem.01259-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens capable of causing hemolytic-uremic syndrome. STEC O157:H7 strains cause the majority of severe disease in the United States; however, there is a growing concern for the amount and severity of illness attributable to non-O157 STEC. Recently, the Food Safety and Inspection Service (FSIS) published the intent to regulate the presence of STEC belonging to serogroups O26, O45, O103, O111, O121, and O145 in nonintact beef products. To ensure the effective control of these bacteria, sensitive and specific tests for their detection will be needed. In this study, we identified single nucleotide polymorphisms (SNPs) in the O-antigen gene cluster that could be used to detect STEC strains of the above-described serogroups. Using comparative DNA sequence analysis, we identified 22 potentially informative SNPs among 164 STEC and non-STEC strains of the above-described serogroups and designed matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) assays to test the STEC allele frequencies in an independent panel of bacterial strains. We found at least one SNP that was specific to each serogroup and also differentiated between STEC and non-STEC strains. Differences in the DNA sequence of the O-antigen gene cluster corresponded well with differences in the virulence gene profiles and provided evidence of different lineages for STEC and non-STEC strains. The SNPs discovered in this study can be used to develop tests that will not only accurately identify O26, O45, O103, O111, O121, and O145 strains but also predict whether strains detected in the above-described serogroups contain Shiga toxin-encoding genes.
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Norwegian sheep are an important reservoir for human-pathogenic Escherichia coli O26:H11. Appl Environ Microbiol 2012; 78:4083-91. [PMID: 22492457 DOI: 10.1128/aem.00186-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previous national survey of Escherichia coli in Norwegian sheep detected eae-positive (eae(+)) E. coli O26:H11 isolates in 16.3% (80/491) of the flocks. The purpose of the present study was to evaluate the human-pathogenic potential of these ovine isolates by comparing them with E. coli O26 isolates from humans infected in Norway. All human E. coli O26 isolates studied carried the eae gene and shared flagellar type H11. Two-thirds of the sheep flocks and 95.1% of the patients harbored isolates containing arcA allele type 2 and espK and were classified as enterohemorrhagic E. coli (EHEC) (stx positive) or EHEC-like (stx negative). These isolates were further divided into group A (EspK2 positive), associated with stx(2-EDL933) and stcE(O103), and group B (EspK1 positive), associated with stx(1a). Although the stx genes were more frequently present in isolates from patients (46.3%) than in those from sheep flocks (5%), more than half of the ovine isolates in the EHEC/EHEC-like group had multiple-locus variable number of tandem repeat analysis (MLVA) profiles that were identical to those seen in stx-positive human O26:H11 isolates. This indicates that EHEC-like ovine isolates may be able to acquire stx-carrying bacteriophages and thereby have the possibility to cause serious illness in humans. The remaining one-third of the sheep flocks and two of the patients had isolates fulfilling the criteria for atypical enteropathogenic E. coli (aEPEC): arcA allele type 1 and espK negative (group C). The majority of these ovine isolates showed MLVA profiles not previously seen in E. coli O26:H11 isolates from humans. However, according to their virulence gene profile, the aEPEC ovine isolates should be considered potentially pathogenic for humans. In conclusion, sheep are an important reservoir of human-pathogenic E. coli O26:H11 isolates in Norway.
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Anklam KS, Kanankege KST, Gonzales TK, Kaspar CW, Döpfer D. Rapid and reliable detection of Shiga toxin-producing Escherichia coli by real-time multiplex PCR. J Food Prot 2012; 75:643-50. [PMID: 22488051 DOI: 10.4315/0362-028x.jfp-11-392] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Escherichia coli O26, O45, O103, O111, O121, O145, and O157 are the predominant Shiga toxin-producing E. coli (STEC) serogroups implicated in outbreaks of human foodborne illness worldwide. The increasing prevalence of these pathogens has important public health implications. Beef products have been considered a main source of foodborne human STEC infections. Robust and sensitive methods for the detection and characterization of these pathogens are needed to determine prevalence and incidence of STEC in beef processing facilities and to improve food safety interventions aimed at eliminating STEC from the food supply. This study was conducted to develop Taqman real-time multiplex PCR assays for the screening and rapid detection of the predominant STEC serogroups associated with human illness. Three serogroup-specific assays targeted the O-antigen gene clusters of E. coli O26 (wzy), O103 (wzx), and O145 (wzx) in assay 1, O45 (wzy), O111 (manC), and O121 (wzx) in assay 2, and O157 (rfbE) in assay 3. The uidA gene also was included in the serogroup-specific assays as an E. coli internal amplification control. A fourth assay was developed to target selected virulence genes for Shiga toxin (stx(1) and stx(2)), intimin (eae), and enterohemolysin (ehxA). The specificity of the serogroup and virulence gene assays was assessed by testing 100 and 62 E. coli strains and non-E. coli control strains, respectively. The assays correctly detected the genes in all strains examined, and no cross-reactions were observed, representing 100 % specificity. The detection limits of the assays were 10(3) or 10(4) CFU/ml for pure cultures and artificially contaminated fecal samples, and after a 6-h enrichment period, the detection limit of the assays was 10(0) CFU/ml. These results indicate that the four real-time multiplex PCR assays are robust and effective for the rapid and reliable detection of the seven predominant STEC serogroups of major public health concern and the detection of their virulence genes.
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Affiliation(s)
- Kelly S Anklam
- Department of Medical Science, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
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Abstract
Lipopolysaccharide on the surface of Escherichia coli constitutes the O antigens which are important virulence factors that are targets of both the innate and adaptive immune systems and play a major role in host-pathogen interactions. O antigens are responsible for antigenic specificity of the strain and determine the O serogroup. The designation of O serogroups is important for classifying E. coli strains, for epidemiological studies, in tracing the source of outbreaks of gastrointestinal or other illness, and for linking the source to the infection. For conventional serogroup identification, serotyping by agglutination reactions against antisera developed for each of the O serogroups has been used. In the last decade, many O-antigen gene clusters that encode for the enzymes responsible for the synthesis of the variable oligosaccharide region on the surface of the bacteria have been sequenced and characterized. Unique gene sequences within the O-antigen gene clusters have been targeted for identification and detection of many O groups using the polymerase chain reaction and microarrays. This review summarizes current knowledge on the DNA sequences of the O-antigen gene clusters, genetic-based methods for O-group determination and detection of pathogenic E. coli based on O-antigen and virulence gene detection, and provides perspectives on future developments in the field.
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Genetic analysis of the Cronobacter sakazakii O4 to O7 O-antigen gene clusters and development of a PCR assay for identification of all C. sakazakii O serotypes. Appl Environ Microbiol 2012; 78:3966-74. [PMID: 22447597 DOI: 10.1128/aem.07825-11] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gram-negative bacterium Cronobacter sakazakii is an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme for C. sakazakii, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for three C. sakazakii serotypes (O1, O2, and O3) have been characterized. In this study, the C. sakazakii O4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology. C. sakazakii O4 shared a similar O-antigen gene cluster with Escherichia coli O103. The general features and anomalies of all seven C. sakazakii O-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for all C. sakazakii O serotypes, a multiplex PCR assay, was developed by screening against 136 strains of C. sakazakii and closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 10(3) CFU of each strain/ml. This study completes the elucidation of C. sakazakii O-antigen genetics and provides a molecular method suitable for the identification of C. sakazakii O1 to O7 strains.
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Fate of Escherichia coli O26 in corn silage experimentally contaminated at ensiling, at silo opening, or after aerobic exposure, and protective effect of various bacterial inoculants. Appl Environ Microbiol 2011; 77:8696-704. [PMID: 21984243 DOI: 10.1128/aem.06320-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) strains are responsible for human illness. Ruminants are recognized as a major reservoir of STEC, and animal feeds, such as silages, have been pointed out as a possible vehicle for the spread of STEC. The present study aimed to monitor the fate of pathogenic E. coli O26 strains in corn material experimentally inoculated (10⁵ CFU/g) during ensiling, just after silo opening, and after several days of aerobic exposure. The addition of 3 bacterial inoculants, Propionibacterium sp., Lactobacillus buchneri, and Leuconostoc mesenteroides (10⁶ CFU/g), was evaluated for their abilities to control these pathogens. The results showed that E. coli O26 could not survive in corn silage 5 days postensiling, and the 3 inoculants tested did not modify the fate of pathogen survival during ensiling. In the case of direct contamination at silo opening, E. coli O26 could be totally eradicated from corn silage previously inoculated with Leuconostoc mesenteroides. The combination of proper ensiling techniques and the utilization of selected bacterial inoculants appears to represent a good strategy to guarantee nutritional qualities of cattle feed while at the same time limiting the entry of pathogenic E. coli into the epidemiological cycle to improve the microbial safety of the food chain.
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Verstraete K, Robyn J, Del-Favero J, De Rijk P, Joris MA, Herman L, Heyndrickx M, De Zutter L, De Reu K. Evaluation of a multiplex-PCR detection in combination with an isolation method for STEC O26, O103, O111, O145 and sorbitol fermenting O157 in food. Food Microbiol 2011; 29:49-55. [PMID: 22029918 DOI: 10.1016/j.fm.2011.08.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/11/2011] [Accepted: 08/11/2011] [Indexed: 11/16/2022]
Abstract
The aim of the current study was to evaluate a multiplex PCR (mPCR) detection test combined with the evaluation of a previously described isolation method. Minced beef, raw-milk cheese and sprouted seed samples were inoculated with low amounts (7-58 cfu 25 g(-1)) of non-stressed, cold-stressed or freeze-stressed clinical STEC strains, including serogroups O26, O103, O111, O145, sorbitol fermenting (SF) O157 and non-sorbitol fermenting (NSF) O157. The inoculated pathogen was detected using a 24 h-enrichment followed by an mPCR protocol, and in parallel isolated using an enrichment step of 6 and 24 h, followed by selective plating of the enriched broth and selective plating of the immunomagnetic separation (IMS) product. Recovery results were evaluated and compared. Successful mPCR detection and isolation was obtained for non-stressed and cold-stressed STEC cells in minced beef and raw-milk cheese samples, except for serogroups O111 and SF O157. For freeze-stressed cells and sprouted seed samples, false negatives were often found. Isolation was better after 24 h-enrichment compared to 6 h-enrichment. IMS improved in some cases the isolation of non-stressed and cold-stressed cells belonging to serogroups O111 and O157 from minced beef and raw-milk cheese and freeze-stressed cells of all tested serogroups from minced beef.
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Affiliation(s)
- K Verstraete
- Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium
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Molecular characterization of multidrug-resistant Escherichia coli isolates from Irish cattle farms. Appl Environ Microbiol 2011; 77:7121-7. [PMID: 21856840 DOI: 10.1128/aem.00601-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study describes the genotypic characteristics of a collection of 100 multidrug-resistant (MDR) Escherichia coli strains recovered from cattle and the farm environment in Ireland in 2007. The most prevalent antimicrobial resistance identified was to streptomycin (100%), followed by tetracycline (99%), sulfonamides (98%), ampicillin (82%), and neomycin (62%). Resistance was mediated predominantly by strA-strB (92%), tetA (67%), sul2 (90%), bla(TEM) (79%), and aphA1 (63%) gene markers, respectively. Twenty-seven isolates harbored a class 1 integrase (intI1), while qacEΔ1 and sul1 markers were identified in 25 and 26 isolates, respectively. The variable regions of these integrons contained aminoglycoside, trimethoprim, and β-lactam resistance determinants (aadA12, aadB-aadA1, bla(OXA-30)-aadA1, dfrA1-aadA1, dfrA7). Class 2 integrons were identified less frequently (4%) and contained the gene cassette array dfrA1-sat1-aadA1. Resistance to ampicillin, neomycin, streptomycin, sulfonamide, and tetracycline was associated with transferable high-molecular-weight plasmids, as demonstrated by conjugation assays. A panel of virulence markers was screened for by PCR, and genes identified included vt1, K5 in 2 isolates, papC in 10 isolates, and PAI IV(536) in 37 isolates. MDR commensal E. coli isolates from Irish cattle displayed considerable diversity with respect to the genes identified. Our findings highlight the importance of the commensal microflora of food-producing animals as a reservoir of transferable MDR.
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Prevalence and growth kinetics of Shiga toxin-producingEscherichia coli(STEC) in bovine offal products in Japan. Epidemiol Infect 2011; 140:655-64. [DOI: 10.1017/s0950268811001105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
SUMMARYRecent epidemiological data suggest a link between the consumption of bovine offal products and Shiga toxin-producingEscherichia coli(STEC) infection in Japan. This study thus examined the prevalence of STEC in various types of these foods. PCR screened 229 bovine offal products for the presence of Shiga toxin (stx) gene. Thirty-eight (16·6%) samples werestxpositive, of which eight were positive forrfbEO157and three were positive forwzyO26. Four O157 and one O26 STEC isolates were finally obtained from small-intestine and omasum products. Notably, homogenates of bovine intestinal products significantly reduced the extent of growth of O157 in the enrichment process compared to homogenates of beef carcass. As co-incubation of O157 with background microbiota complex from bovine intestinal products in buffered peptone water, in the absence of meat samples, tended to reduce the extent of growth of O157, we reasoned that certain microbiota present in offal products played a role. In support of this, inoculation of genericE. colifrom bovine intestinal products into the homogenates significantly reduced the extent of growth of O157 in the homogenates of bovine intestinal and loin-beef products, and this effect was markedly increased when these homogenates were heat-treated prior to inoculation. Together, this report provides first evidence of the prevalence of STEC in a variety of bovine offal products in Japan. The prevalence data herein may be useful for risk assessment of those products as a potential source of human STEC infection beyond the epidemiological background. The growth characteristic of STEC O157 in offal products also indicates the importance of being aware when to test these food products.
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Bosilevac JM, Koohmaraie M. Prevalence and characterization of non-O157 shiga toxin-producing Escherichia coli isolates from commercial ground beef in the United States. Appl Environ Microbiol 2011; 77:2103-12. [PMID: 21257806 PMCID: PMC3067332 DOI: 10.1128/aem.02833-10] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 is a Shiga toxin (stx)-producing E. coli (STEC) strain that has been classified as an adulterant in U.S. beef. However, numerous other non-O157 STEC strains are associated with diseases of various severities and have become an increasing concern to the beef industry, regulatory officials, and the public. This study reports on the prevalence and characterization of non-O157 STEC in commercial ground beef samples (n = 4,133) obtained from numerous manufacturers across the United States over a period of 24 months. All samples were screened by DNA amplification for the presence of Shiga toxin genes, which were present in 1,006 (24.3%) of the samples. Then, culture isolation of an STEC isolate from all samples that contained stx(1) and/or stx(2) was attempted. Of the 1,006 positive ground beef samples screened for stx, 300 (7.3% of the total of 4,133) were confirmed to have at least one strain of STEC present by culture isolation. In total, 338 unique STEC isolates were recovered from the 300 samples that yielded an STEC isolate. All unique STEC isolates were serotyped and were characterized for the presence of known virulence factors. These included Shiga toxin subtypes, intimin subtypes, and accessory virulence factors related to adherence (saa, iha, lifA), toxicity (cnf, subA, astA), iron acquisition (chuA), and the presence of the large 60-MDa virulence plasmid (espP, etpD, toxB, katP, toxB). The isolates were also characterized by use of a pathogenicity molecular risk assessment (MRA; based on the presence of various O-island nle genes). Results of this characterization identified 10 STEC isolates (0.24% of the 4,133 total) that may be considered a significant food safety threat, defined by the presence of eae, subA, and nle genes.
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Affiliation(s)
- Joseph M Bosilevac
- USDA, ARS, U.S. Meat Animal Research Center, P.O. Box 166, State Spur 18D, Clay Center, NE 68933-0166, USA.
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Valadez AM, Debroy C, Dudley E, Cutter CN. Multiplex PCR detection of Shiga toxin-producing Escherichia coli strains belonging to serogroups O157, O103, O91, O113, O145, O111, and O26 experimentally inoculated in beef carcass swabs, beef trim, and ground beef. J Food Prot 2011; 74:228-39. [PMID: 21333142 DOI: 10.4315/0362-028x.jfp-10-386] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Numerous foodborne outbreaks are attributed to Shiga toxin-producing Escherichia coli (STEC) and have been recognized for causing gastrointestinal disease in humans. Beef products have been considered the principal source of STEC. A multiplex PCR assay enabling simultaneous detection of STEC O103, O91, O113, O145, O111, O157, and O26 was developed and evaluated in artificially contaminated beef carcass swabs, beef trim, and ground beef after overnight enrichment. Individual serogroups were experimentally inoculated at low (1 to 10 CFU/ml) and high (11 to 100 CFU/ml) levels, and with a cocktail of strains belonging to two, four, and six serogroups. There was no significant difference in detecting single STEC strains under the different conditions. Only when strains were combined were there significant differences in detection of all cocktail isolates in some of the beef products. To address this issue, four serogroups were experimentally inoculated together at three different estimated levels (10, 10(2), and 10(3) CFU/ml) in all three beef products. Results yielded no significant difference in detecting STEC at the three inoculation levels (10, 10(2), and 10(3) CFU/ml) in trim and carcass swabs, but there was a significant difference in detecting STEC at the lowest levels (10 and 10(2) CFU/ml) in the 80:20 nonirradiated ground beef, and in the detection of STEC in irradiated ground beef. The findings from this study could provide industry and government agencies with a tool to evaluate the prevalence and incidence of STEC in beef products and their processing environments.
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Affiliation(s)
- Angela M Valadez
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Fratamico PM, Bagi LK, Cray WC, Narang N, Yan X, Medina M, Liu Y. Detection by multiplex real-time polymerase chain reaction assays and isolation of Shiga toxin-producing Escherichia coli serogroups O26, O45, O103, O111, O121, and O145 in ground beef. Foodborne Pathog Dis 2011; 8:601-7. [PMID: 21214490 DOI: 10.1089/fpd.2010.0773] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Six Shiga toxin-producing Escherichia coli (STEC) serogroups, which include O26, O45, O103, O111, O121, and O145, are responsible for the majority of non-O157 STEC infections in the United States, representing a growing public health concern. Cattle and other ruminants are reservoirs for these pathogens; thus, food of bovine origin may be a vehicle for infection with non-O157 STEC. Methods for detection of these pathogens in animal reservoirs and in food are needed to determine their prevalence and to develop intervention strategies. This study describes a method for detection of non-O157 STEC in ground beef, consisting of enrichment in modified tryptic soy broth at 42°C, followed by real-time multiplex polymerase chain reaction (PCR) assays targeting stx(1), stx(2), and genes in the O-antigen gene clusters of the six serogroups, [corrected] and then immunomagnetic separation (IMS) followed by plating onto Rainbow® Agar O157 and PCR assays for confirmation of isolates. All ground beef samples artificially inoculated with 1-2 and 10-20 CFU/25 g of ground beef consistently gave positive results for all of the target genes, including the internal amplification control using the multiplex real-time PCR assays after enrichment in modified tryptic soy broth for a total of 24 h (6 h at 37°C and 18 h at 42°C). The detection limit of the real-time multiplex PCR assays was ∼50 CFU per PCR. IMS for O26, O103, O111, and O145 was performed with commercially available magnetic beads, and the IMS beads for O45 and O121 were prepared using polyclonal antiserum against these serogroups. A large percentage of the presumptive colonies of each serogroup picked from Rainbow Agar O157 were confirmed as the respective serogroups; however, the percent recovery of STEC O111 was somewhat lower than that of the other serogroups. This work provides a method for detection and isolation in ground beef and potentially other foods of non-O157 STEC of major public health concern.
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Affiliation(s)
- Pina M Fratamico
- Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
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Verstraete K, De Zutter L, Messens W, Herman L, Heyndrickx M, De Reu K. Effect of the enrichment time and immunomagnetic separation on the detection of Shiga toxin-producing Escherichia coli O26, O103, O111, O145 and sorbitol positive O157 from artificially inoculated cattle faeces. Vet Microbiol 2010; 145:106-12. [DOI: 10.1016/j.vetmic.2010.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 03/03/2010] [Accepted: 03/08/2010] [Indexed: 11/25/2022]
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Fratamico PM, Yan X, Liu Y, DebRoy C, Byrne B, Monaghan A, Fanning S, Bolton D. Escherichia coliserogroup O2 and O28ac O-antigen gene cluster sequences and detection of pathogenicE. coliO2 and O28ac by PCR. Can J Microbiol 2010; 56:308-16. [DOI: 10.1139/w10-010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The O-antigen gene clusters of Escherichia coli serogroups O2 and O28ac were sequenced, and PCR assays were developed to identify strains belonging to these 2 serogroups. Sixteen and 8 open reading frames were mapped to these loci in E. coli O2:H4 U 9-41 and E. coli O28ac:H25 96-3286, respectively. The wzx (O-antigen flippase) and wzy (O-antigen polymerase) genes in the E. coli O2 and O28ac O-antigen gene clusters were selected as targets for PCR assays for their identification. PCR assays targeting the wzx and wzy genes were specific for these serogroups, with one exception. Escherichia coli serogroup O42 strains gave positive results with wzx and wzy PCR assays targeting E. coli O28ac, and antiserum raised against O42 cross-reacted with serogroup O28ac strains. The O-antigen gene cluster of a strain of E. coli serogroup O42 was sequenced, and there were only 3 nt differences between the O-antigen gene clusters of the O28ac and O42 strains. Multiplex PCR assays targeting the O2 wzx gene, the stx1, stx2, hly, eae, and saa genes, and the O28ac wzx, ial, ipaC, and ipaH genes were developed for detecting Shiga toxin-producing E. coli O2 strains and enteroinvasive E. coli O28ac strains, respectively. The O2 and O28ac wzx and wzy genes can be used as diagnostic markers in PCR assays for rapid identification of these serogroups as an alternative to serotyping, and the multiplex PCR assays targeting serogroup-specific genes in combination with virulence genes can be used to identify and to detect pathogenic serogroup O2 and O28ac strains.
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Affiliation(s)
- Pina M. Fratamico
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Xianghe Yan
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Yanhong Liu
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Chitrita DebRoy
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Brian Byrne
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Aine Monaghan
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Seamus Fanning
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Declan Bolton
- Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 104 Wiley Lab, Wiley Lane, University Park, PA 16802, USA
- Food Safety Department, Ashtown Food Research Centre, Teagasc, Ashtown, Dublin 15, Ireland
- UCD Centre for Food Safety, School of Agriculture, Food Science, and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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Goswami P, Gyles C, Friendship R, Poppe C, Vinogradov E, Boerlin P. The Escherichia coli O149 rfb gene cluster and its use for the detection of porcine E. coli O149 by real-time PCR. Vet Microbiol 2010; 141:120-6. [DOI: 10.1016/j.vetmic.2009.08.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 07/21/2009] [Accepted: 08/11/2009] [Indexed: 11/24/2022]
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Abstract
The O antigen, consisting of many repeats of an oligosaccharide unit, is part of the lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria. It is on the cell surface and appears to be a major target for both immune system and bacteriophages, and therefore becomes one of the most variable cell constituents. The variability of the O antigen provides the major basis for serotyping schemes of Gram-negative bacteria. The genes responsible for the synthesis of O antigen are usually in a single cluster known as O antigen gene cluster, and their location on the chromosome within a species is generally conserved. Three O antigen biosynthesis pathways including Wzx/Wzy, ABC-transporter and Synthase have been discovered. In this chapter, the traditional and molecular O serotyping schemes are compared, O antigen structures and gene clusters of well-studied species are described, processes for formation and distribution of the variety of O antigens are discussed, and finally, the role of O antigen in bacterial virulence.
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Affiliation(s)
- Lei Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, China.
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Liu Y, Fratamico P, Debroy C, Bumbaugh AC, Allen JW. DNA sequencing and identification of serogroup-specific genes in the Escherichia coli O118 O antigen gene cluster and demonstration of antigenic diversity but only minor variation in DNA sequence of the O antigen clusters of E. coli O118 and O151. Foodborne Pathog Dis 2008; 5:449-57. [PMID: 18673069 DOI: 10.1089/fpd.2008.0096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The DNA sequence of the O antigen gene cluster of an Escherichia coli serogroup O118 strain was determined, and 13 open reading frames (ORFs) were identified, encoding genes required for O antigen sugar biosynthesis, transfer, and processing. Polymerase chain reaction (PCR) assays targeting the wzx (O antigen flippase) and wzy (O antigen polymerase) genes in the O antigen gene cluster of E. coli O118 were designed for identification of these serogroups. Specificity testing using strains belonging to E. coli O118 isolated from various sources, representative strains of 167 other E. coli O serogroups, and 20 non-E. coli bacteria revealed that the PCR assays were specific for E. coli O118. Thus, the PCR assays can be used for rapid identification of E. coli O118 as an alterative to typing using antisera. However, the PCR assays targeting the E. coli O118 wzx and wzy genes were also positive using E. coli serogroup O151 DNA. Therefore, the sequence of the O antigen gene cluster of E. coli O151 was determined, and it was very similar to that of E. coli O118, with only three nucleotide differences. Although the lipopolysaccharide profiles of O118 and O151 showed differences, multilocus sequence typing of E. coli O118 and O151 strains only revealed minor variation at the nucleotide level. Since E. coli O118 strains are more frequently isolated from humans, animals, and the environment than E. coli O151, serogroup O151 may likely be a minor variant of E. coli O118. Further studies are needed to elucidate this possibility.
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Affiliation(s)
- Yanhong Liu
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA.
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44
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The DNA Sequence of the Escherichia coli O22 O-Antigen Gene Cluster and Detection of Pathogenic Strains Belonging to E. coli Serogroups O22 and O91 by Multiplex PCR Assays Targeting Virulence Genes and Genes in the Respective O-Antigen Gene Clusters. FOOD ANAL METHOD 2008. [DOI: 10.1007/s12161-008-9046-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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45
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Liu B, Knirel YA, Feng L, Perepelov AV, Senchenkova SN, Wang Q, Reeves PR, Wang L. Structure and genetics ofShigellaO antigens. FEMS Microbiol Rev 2008; 32:627-53. [DOI: 10.1111/j.1574-6976.2008.00114.x] [Citation(s) in RCA: 241] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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46
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Jenkins C, Evans J, Chart H, Willshaw GA, Frankel G. Escherichia coli serogroup O26--a new look at an old adversary. J Appl Microbiol 2008; 104:14-25. [PMID: 18171379 DOI: 10.1111/j.1365-2672.2007.03465.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Escherichia coli serogroup O26 played an important part in the early work on Verocytotoxin and is an established diarrhoeal pathogen. Recently, Verocytotoxigenic E. coli (VTEC) O26 has been increasingly associated with diarrhoeal disease and frequently linked to outbreaks and cases of haemolytic uraemic syndrome (HUS). This review investigates the pathogenicity, geographical distribution, changing epidemiology, routes of transmission and improved detection of VTEC O26. Laboratory data on VTEC O26 isolates and clinical data on HUS suggest a true difference in the incidence of VTEC O26 in different geographic locations. However, few diagnostic laboratories use molecular methods to detect VTEC and so it is difficult to assess the role of VTEC O26 in causing diarrhoeal disease. VTEC O26 is frequently found in the cattle population but rarely in food. However, the small number of outbreaks analysed to date are thought to be food-borne rather than associated with direct or indirect contact with livestock or their faeces. The increase in awareness of VTEC O26 in the clinical and veterinary setting has coincided with the development of novel techniques that have improved our ability to detect and characterize this pathogen.
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Affiliation(s)
- C Jenkins
- Department of Medical Microbiology, Royal Free Hospital, NW3 2QG, London, UK.
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Auvray F, Lecureuil C, Taché J, Perelle S, Fach P. Development of a 5'-nuclease PCR assay for the identification of Escherichia coli strains expressing the flagellar antigen H21 and their detection in food after enrichment. J Appl Microbiol 2008; 104:899-905. [DOI: 10.1111/j.1365-2672.2007.03607.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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48
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Aktan I, Carter B, Wilking H, La Ragione RM, Wieler L, Woodward MJ, Anjum MF. Influence of geographical origin, host animal and stx gene on the virulence characteristics of Escherichia coli O26 strains. J Med Microbiol 2008; 56:1431-1439. [PMID: 17965341 DOI: 10.1099/jmm.0.47311-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The influence of geographical origin, host animal and presence of the stx gene on the virulence of Escherichia coli O26 strains from ruminants was determined in this study. A clear association was found between the virulence profile and geographical origin of Shiga-toxigenic E. coli (STEC) O26 strains, with UK STEC O26 strains harbouring virtually identical profiles, whilst central European strains showed considerable heterogeneity in plasmid-encoded genes. The former group were also more likely to be non-motile and katP gene positive. Comparison of UK STEC and atypical enteropathogenic E. coli (aEPEC) O26 strains showed that the presence of the stx1 gene was positively correlated with the presence of espP and katP genes and negatively associated with the presence of the yagP-yagT region and with rhamnose fermentation. In contrast to the uniform profiles of STEC O26 strains from ruminants in the UK, aEPEC O26 strains of bovine and ovine origin showed diverse profiles both within and between groups, and could not be separated into discrete groups. These results indicate that the characteristics of UK O26 strains from ruminants are distinct from those of O26 strains from ruminants and humans in other regions in central Europe. Such differences are expected to influence the zoonotic potential of this pathogen and the subsequent incidence of O26-associated human disease.
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Affiliation(s)
- Ilknur Aktan
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA), Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.,Department of Veterinary Clinical Science and Animal Husbandry, University of Liverpool, Neston, South Wirral CH64 7TE, UK
| | - Ben Carter
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA), Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Hendrik Wilking
- Institute of Microbiology and Epizootics, Free University Berlin, D-10115 Berlin, Germany
| | - Roberto M La Ragione
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA), Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Lothar Wieler
- Institute of Microbiology and Epizootics, Free University Berlin, D-10115 Berlin, Germany
| | - Martin J Woodward
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA), Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Muna F Anjum
- Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA), Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK
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Plainvert C, Bidet P, Peigne C, Barbe V, Médigue C, Denamur E, Bingen E, Bonacorsi S. A new O-antigen gene cluster has a key role in the virulence of the Escherichia coli meningitis clone O45:K1:H7. J Bacteriol 2007; 189:8528-36. [PMID: 17905975 PMCID: PMC2168960 DOI: 10.1128/jb.01013-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A new highly pathogenic clone of Escherichia coli meningitis strains harboring the unusual serogroup O45 has recently emerged in France. To gain insight into the pathogenicity of this new clone, we investigated the possible role of antigen O45 in the virulence of strain S88 (O45:K1:H7), representative of this emerging clone. We first showed that the S88 O-antigen gene cluster sequence differs from that of O45 in the reference strain E. coli 96-3285, suggesting that the two O45 polysaccharides, while probably sharing a community of epitopes, represent two different antigens. The unique functional organization of the two O-antigen gene clusters and the low DNA sequence homology of the orthologous genes suggest that the two loci originated from a common ancestor and have since undergone multiple recombination events. Phylogenetic analysis based on the flanking gene gnd sequences indicates that the S88 antigen O45 (O45(S88)) gene cluster may have been acquired, at least in part, from another member of the Enterobacteriaceae. Mutagenesis of the O45(S88) antigen gene cluster was used for functional analysis of the loci and revealed the crucial role of the O polysaccharide in S88 virulence in a neonatal rat meningitis model. We also developed a PCR method to specifically identify the O45(S88) antigen gene cluster. Together, our findings suggest that horizontal acquisition of a new O-antigen gene cluster, at least partly from another species, may have been a key event in the emergence and virulence of the E. coli O45:K1:H7 clone in France.
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Affiliation(s)
- Céline Plainvert
- Service de Microbiologie, Hôpital Robert Debré, 48 blvd. Sérurier, 75395 Paris cedex 19, France
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50
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Gilmour MW, Olson AB, Andrysiak AK, Ng LK, Chui L. Sequence-based typing of genetic targets encoded outside of the O-antigen gene cluster is indicative of Shiga toxin-producing Escherichia coli serogroup lineages. J Med Microbiol 2007; 56:620-628. [PMID: 17446284 PMCID: PMC2884935 DOI: 10.1099/jmm.0.47053-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Serogroup classifications based upon the O-somatic antigen of Shiga toxin-producing Escherichia coli (STEC) provide significant epidemiological information on clinical isolates. Each O-antigen determinant is encoded by a unique cluster of genes present between the gnd and galF chromosomal genes. Alternatively, serogroup-specific polymorphisms might be encoded in loci that are encoded outside of the O-antigen gene cluster. Segments of the core bacterial loci mdh, gnd, gcl, ppk, metA, ftsZ, relA and metG for 30 O26 STEC strains have previously been sequenced, and comparative analyses to O157 distinguished these two serogroups. To screen these loci for serogroup-specific traits within a broader range of clinically significant serogroups, DNA sequences were obtained for 19 strains of 10 additional STEC serogroups. Unique alleles were observed at the gnd locus for each examined STEC serogroup, and this correlation persisted when comparative analyses were extended to 144 gnd sequences from 26 O-serogroups (comprising 42 O : H-serotypes). These included O157, O121, O103, O26, O5 : non-motile (NM), O145 : NM, O113 : H21, O111 : NM and O117 : H7 STEC; and furthermore, non-toxin encoding O157, O26, O55, O6 and O117 strains encoded distinct gnd alleles compared to STEC strains of the same serogroup. DNA sequencing of a 643 bp region of gnd was, therefore, sufficient to minimally determine the O-antigen of STEC through molecular means, and the location of gnd next to the O-antigen gene cluster offered additional support for the co-inheritance of these determinants. The gnd DNA sequence-based serogrouping method could improve the typing capabilities for STEC in clinical laboratories, and was used successfully to characterize O121 : H19, O26 : H11 and O177 : NM clinical isolates prior to serological confirmation during outbreak investigations.
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Affiliation(s)
- Matthew W. Gilmour
- National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Adam B. Olson
- National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada
| | - Ashleigh K. Andrysiak
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Lai-King Ng
- National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Linda Chui
- Alberta Provincial Laboratory for Public Health, Edmonton, Alberta, Canada
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