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Onyeka LO, Adesiyun AA, Keddy KH, Manqele A, Madoroba E, Thompson PN. Prevalence, risk factors and molecular characteristics of Shiga toxin-producing Escherichia coli in beef abattoirs in Gauteng, South Africa. Food Control 2021. [DOI: 10.1016/j.foodcont.2020.107746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Sasaki Y, Iwata T, Uema M, Asakura H. [Prevalence and Characterization of Campylobacter in Bile from Bovine Gallbladders]. Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) 2020; 61:126-131. [PMID: 33012766 DOI: 10.3358/shokueishi.61.126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Campylobacter is one of the most important causes of food-borne infectious diseases. Antibiotics are rarely needed to treat campylobacteriosis, but occasionally used in severe or prolonged cases. Consumption of contaminated bovine liver is a source of campylobacteriosis. Bovine liver can be contaminated with Campylobacter on the surface and inside by the bile at slaughterhouses. Therefore, we investigated the current prevalence and characteristics of Campylobacter in bovine bile at a slaughterhouse. Campylobacter was isolated from 35.7% (55/154) of bile samples. C. jejuni and C. fetus were the two most frequent species. High antimicrobial resistant rates in C. jejuni were observed against tetracycline (63.0%) and ciprofloxacin (44.4%). Multi-locus sequence typing divided C. jejuni isolates (27 isolates) into 12 sequence types (STs) in which ST806 was the most frequent ST and accounted for 37.0%. All C. fetus were identified as C. fetus subsp. fetus which can cause systemic infections. High antimicrobial resistant rates in C. fetus were observed against ciprofloxacin (66.6%), streptomycin (58.3%) and tetracycline (33.3%). All the C. fetus isolates were divided into two STs, ST3 (16 isolates) and ST6 (8 isolates). Of the 16 ST3 isolates, 15 (93.8%) were resistant to both streptomycin and ciprofloxacin. Our data shows high prevalence of Campylobacter in bovine bile and their high rates of antimicrobial resistance. Preventing bile contamination of bovine liver at slaughterhouses is thus considered to be one of control measures to reduce the risk of Campylobacter infections.
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Affiliation(s)
- Yoshimasa Sasaki
- Division of Biomedical Food Research, National Institute of Health Sciences
| | | | - Masashi Uema
- Division of Biomedical Food Research, National Institute of Health Sciences
| | - Hiroshi Asakura
- Division of Biomedical Food Research, National Institute of Health Sciences
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3
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Onyeka LO, Adesiyun AA, Keddy KH, Madoroba E, Manqele A, Thompson PN. Shiga Toxin-Producing Escherichia coli Contamination of Raw Beef and Beef-Based Ready-to-Eat Products at Retail Outlets in Pretoria, South Africa. J Food Prot 2020; 83:476-484. [PMID: 32065651 DOI: 10.4315/0362-028x.jfp-19-372] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/26/2019] [Indexed: 01/12/2023]
Abstract
ABSTRACT A cross-sectional study was conducted to determine the prevalence of and factors associated with Shiga toxin-producing Escherichia coli (STEC) in raw beef and ready-to-eat (RTE) beef products sold in 31 retail outlets in Pretoria, South Africa, and nearby areas. A total of 463 beef and RTE samples were screened for four STEC virulence genes (stx1, stx2, eaeA, and hlyA) and seven O-serogroups (O113, O157, O26, O91, O145, O111, and O103) with a multiplex PCR assay. The total aerobic plate count (TAPC) per gram was also determined. A total of 38 STEC isolates were recovered and characterized by conventional PCR assay and serotyping. The overall prevalence of STEC in the beef and RTE samples tested was 16.4% (76 of 463 samples; 95% confidence interval, 13 to 20%). The prevalence of STEC differed significantly by product type (P < 0.0001), with the highest prevalence (35%) detected in boerewors (spicy sausage). The STEC prevalences in minced beef, brisket, RTE cold beef, and biltong were 18, 13, 9, and 5%, respectively. The most frequently detected stx gene was stx2 (13%), and STEC serogroups from recovered isolates were detected at the following prevalences: O2, 15%; O8, 12%; O13, 15%; O20, 8%; O24, 3%; O39, 3%; O41, 8%; O71, 3%; O76, 3%; O150, 12%; and O174, 3%. A high proportion (77%) of the samples had TAPCs that exceeded the South African microbiological standards for meat export (5.0 log CFU/g). The prevalence of O157 STEC (16%) and the diversity of non-O157 STEC serogroups found in five common beef-based products from retail outlets in South Africa suggest exposure of raw beef and beef products to multiple contamination sources during carcass processing and/or cutting and handling at retail outlets. These data provide direct estimates of the potential health risk to consumers from undercooked contaminated products and indicate the need to improve sanitary practices during slaughter and processing of beef and beef-based RTE products. A risk-based surveillance system for STEC may be needed. HIGHLIGHTS
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Affiliation(s)
- Libby O Onyeka
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0001-9470-9421 [A.A.A.]; https://orcid.org/0000-0002-2268-9748 [P.N.T.]).,Department of Veterinary Public Health and Preventive Medicine, College of Veterinary Medicine, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria
| | - Abiodun A Adesiyun
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0001-9470-9421 [A.A.A.]; https://orcid.org/0000-0002-2268-9748 [P.N.T.])
| | - Karen H Keddy
- Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Evelyn Madoroba
- Agricultural Research Council, Onderstepoort Veterinary Research, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0002-5400-343X [E.M.]).,Department of Biochemistry & Microbiology, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, KwaZulu-Natal, South Africa
| | - Ayanda Manqele
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0001-9470-9421 [A.A.A.]; https://orcid.org/0000-0002-2268-9748 [P.N.T.]).,Agricultural Research Council, Onderstepoort Veterinary Research, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0002-5400-343X [E.M.])
| | - Peter N Thompson
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0001-9470-9421 [A.A.A.]; https://orcid.org/0000-0002-2268-9748 [P.N.T.])
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Manage DP, Lauzon J, Jones CM, Ward PJ, Pilarski LM, Pilarski PM, McMullen LM. Detection of pathogenic Escherichia coli on potentially contaminated beef carcasses using cassette PCR and conventional PCR. BMC Microbiol 2019; 19:175. [PMID: 31362696 PMCID: PMC6668150 DOI: 10.1186/s12866-019-1541-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 07/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Over a one year period, swabs of 820 beef carcasses were tested for the presence of Shiga toxin-producing Escherichia coli by performing Polymerase Chain Reaction (PCR) in a novel technology termed "cassette PCR", in comparison to conventional liquid PCR. Cassette PCR is inexpensive and ready-to-use. The operator need only add the sample and press "go". Cassette PCR can simultaneously test multiple samples for multiple targets. Carcass swab samples were first tested for the presence of STEC genes (O157, eae, stx1 and stx2). Samples were considered to be pathogenic if positive for eae plus stx1 and/or stx2. For samples scored as pathogenic, further testing screened for 6 additional high frequency O-antigens (O26, O45, O103, O111, O121, and O145). RESULTS Of the 820 samples, 41% were pathogenic and 30% were O157 positive. Of these, 19% of samples were positive for O157 and carried potentially pathogenic E. coli (eae plus stx1 and/or stx2). Of all samples identified as carrying pathogenic E. coli, 18.9, 38.8, 41.4, 0, 36.1, and 4.1% respectively were positive for O26, O45, O103, O111, O121, and O145. To validate cassette PCR testing, conventional PCR using STEC primers was performed on each of the 820 samples. Only 148 of 3280 cassette PCR tests were discordant with conventional PCR results. However, further fractional testing showed that 110 of these 148 PCRs reflected low numbers of E. coli in the enrichment broth and could be explained as due to Poisson limiting dilution of the template, affecting both cassette PCR and conventional PCR. Of the remaining 38 discordant tests, 27 initial capillary PCRs and 10 initial conventional tests were nominally discordant between cassette and conventional PCR, perhaps reflecting human/technical error on both sides of the comparison. CONCLUSIONS Contaminated beef carcass swabs were often complex, likely harboring more than one strain of pathogenic E. coli. Cassette PCR had 98.8% concordance with parallel conventional PCR for detection of STEC genes. This indicates that cassette PCR is highly reliable for detecting multiple pathogens in beef carcass swabs from processing plants.
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Affiliation(s)
- Dammika P Manage
- Department of Oncology, University of Alberta and Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2, Canada
| | - Jana Lauzon
- Department of Oncology, University of Alberta and Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2, Canada
| | - Christina M Jones
- Department of Oncology, University of Alberta and Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2, Canada
| | - Patrick J Ward
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada
| | - Linda M Pilarski
- Department of Oncology, University of Alberta and Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2, Canada
| | - Patrick M Pilarski
- Division of Physical Medicine & Rehabilitation, Department of Medicine, University of Alberta, 5-005 Katz Group Centre for Pharmacy and Health Research, Edmonton, AB, T6G 2E1, Canada
| | - Lynn M McMullen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada.
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Stromberg ZR, Redweik GAJ, Mellata M. Detection, Prevalence, and Pathogenicity of Non-O157 Shiga Toxin-Producing Escherichia coli from Cattle Hides and Carcasses. Foodborne Pathog Dis 2019; 15:119-131. [PMID: 29638166 DOI: 10.1089/fpd.2017.2401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cattle are a major reservoir for Shiga toxin-producing Escherichia coli (STEC) and harbor these bacteria in the intestinal tract. The prevalence, concentration, and STEC serogroup isolated in cattle varies between individuals. Hide removal at slaughter serves as a major point of carcass contamination and ultimately beef products. Certain STEC serogroups, such as O26, O45, O103, O111, O121, O145, and O157, containing the intestinal adherence factor intimin, pose a large economic burden to food producers because of testing and recalls. Human infection with STEC can cause illnesses ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome, and is commonly acquired through ingestion of contaminated foods, often beef products. Previously, most studies focused on O157 STEC, but there is growing recognition of the importance of non-O157 STEC serogroups. This review summarizes detection methods, prevalence, and methods for prediction of pathogenicity of non-O157 STEC from cattle hides and carcasses. A synthesis of procedures is outlined for general non-O157 STEC and targeted detection of specific STEC serogroups. Standardization of sample collection and processing procedures would allow for more robust comparisons among studies. Presence of non-O157 STEC isolated from cattle hides and carcasses and specific factors, such as point of sample collection and season, are summarized. Also, factors that might influence STEC survival on these surfaces, such as the microbial population on hides and microbial adherence genes, are raised as topics for future investigation. Finally, this review gives an overview on studies that have used genetic and cell-based methods to identify specific phenotypes of non-O157 STEC strains isolated from cattle to assess their risk to human health.
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Affiliation(s)
- Zachary R Stromberg
- Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa
| | - Graham A J Redweik
- Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa
| | - Melha Mellata
- Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa
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Detection of Shiga toxin-producing Escherichia coli, stx1, stx2 and Salmonella by two high resolution melt curve multiplex real-time PCR. Food Control 2019. [DOI: 10.1016/j.foodcont.2018.09.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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7
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Akyol I. Development and application of RTi-PCR method for common food pathogen presence and quantity in beef, sheep and chicken meat. Meat Sci 2018; 137:9-15. [DOI: 10.1016/j.meatsci.2017.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 10/22/2017] [Accepted: 11/01/2017] [Indexed: 10/18/2022]
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8
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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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Abstract
Shiga toxin-producing Escherichia coli (STEC) strains are commonly found in the intestine of ruminant species of wild and domestic animals. Excretion of STEC with animal feces results in a broad contamination of food and the environment. Humans get infected with STEC through ingestion of contaminated food, by contact with the environment, and from STEC-excreting animals and humans. STEC strains can behave as human pathogens, and some of them, called enterohemorrhagic E. coli (EHEC), may cause hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Because of the diversity of STEC types, detection strategies for STEC and EHEC are based on the identification of Shiga toxins or the underlying genes. Cultural enrichment of STEC from test samples is needed for identification, and different protocols were developed for this purpose. Multiplex real-time PCR protocols (ISO/CEN TS13136 and USDA/FSIS MLG5B.01) have been developed to specifically identify EHEC by targeting the LEE (locus of enterocyte effacement)-encoded eae gene and genes for EHEC-associated O groups. The employment of more genetic markers (nle and CRISPR) is a future challenge for better identification of EHEC from any kinds of samples. The isolation of STEC or EHEC from a sample is required for confirmation, and different cultivation protocols and media for this purpose have been developed. Most STEC strains present in food, animals, and the environment are eae negative, but some of these strains can cause HC and HUS in humans as well. Phenotypic assays and molecular tools for typing EHEC and STEC strains are used to detect and characterize human pathogenic strains among members of the STEC group.
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Singh P, Mustapha A. Multiplex real-time PCR assays for detection of eight Shiga toxin-producing Escherichia coli in food samples by melting curve analysis. Int J Food Microbiol 2015; 215:101-8. [PMID: 26355415 DOI: 10.1016/j.ijfoodmicro.2015.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/25/2015] [Accepted: 08/28/2015] [Indexed: 11/18/2022]
Abstract
Shiga toxin-producing Escherichia coli (STEC) are pathogenic strains of E. coli that can cause bloody diarrhea and kidney failure. Seven STEC serogroups, O157, O26, O45, O103, O111, O121 and O145 are responsible for more than 71% of the total infections caused by this group of pathogens. All seven serogroups are currently considered as adulterants in non-intact beef products in the U.S. In this study, two multiplex melt curve real-time PCR assays with internal amplification controls (IACs) were standardized for the detection of eight STEC serogroups. The first multiplex assay targeted E. coli serogroups O145, O121, O104, and O157; while the second set detected E. coli serogroups O26, O45, O103 and O111. The applicability of the assays was tested using 11 different meat and produce samples. For food samples spiked with a cocktail of four STEC serogroups with a combined count of 10 CFU/25 g food, all targets of the multiplex assays were detected after an enrichment period of 6h. The assays also worked efficiently when 325 g of food samples were spiked with 10 CFU of STECs. The assays are not dependent on fluorescent-labeled probes or immunomagnetic beads, and can be used for the detection of eight STEC serogroups in less than 11h. Routine preliminary screening of STECs in food samples is performed by testing for the presence of STEC virulence genes. The assays developed in this study can be useful as a first- or second-tier test for the identification of the eight O serogroup-specific genes in suspected food samples.
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Affiliation(s)
- Prashant Singh
- Food Science Program, University of Missouri, Columbia, USA
| | - Azlin Mustapha
- Food Science Program, University of Missouri, Columbia, USA.
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11
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Diversity of CRISPR loci and virulence genes in pathogenic Escherichia coli isolates from various sources. Int J Food Microbiol 2015; 204:41-6. [DOI: 10.1016/j.ijfoodmicro.2015.03.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 03/15/2015] [Accepted: 03/22/2015] [Indexed: 12/16/2022]
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12
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Hegde NV, Cote R, Jayarao BM, Muldoon M, Lindpaintner K, Kapur V, Debroy C. Detection of the top six non-O157 Shiga toxin-producing Escherichia coli O groups by ELISA. Foodborne Pathog Dis 2014; 9:1044-8. [PMID: 23134286 DOI: 10.1089/fpd.2012.1231] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is a growing concern of a public health risk associated with non-O157 Shiga toxin-producing Escherichia coli (STEC) since E. coli serogroups O26, O45, O103, O111, O121, and O145 are frequently implicated in outbreaks of human illness worldwide. Recently, the Food Safety and Inspection Service of the U.S. Department of Agriculture declared these six STEC O groups to be adulterants in beef. We describe here a rapid, sensitive, and highly specific enzyme-linked immunosorbent assay (ELISA) for the detection of these top six non-O157 STEC O groups. The assays were tested against 174 reference E. coli O groups, with 60 clinical isolates belonging to the target O groups and 10 non-E coli strains belonging to the family Enterobacteriaceae. Assays for serogroups O103, O111, and O121 exhibited 100% specificity, while assays for serogroups O26 and O45 had 98.2% specificity, and O145 had 99.1% specificity. ELISA conducted using artificially inoculated ground beef samples displayed 100% accuracy. The sensitivity of the assay was 5×10(5) colony-forming unit (CFU)/mL, with limits of detection in the range of 1-10 CFU/25 g of ground beef sample following enrichment. The findings of the study suggest that the assay described is simple and rapid, and can be employed to detect target STEC O groups in beef and other food samples. In addition, the assay provides a conceptual framework that can be adapted for the development of similar tests for the rapid detection of other serogroups of E. coli.
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Affiliation(s)
- Narasimha V Hegde
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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Tang Y, Kim H, Singh AK, Aroonnual A, Bae E, Rajwa B, Fratamico PM, Bhunia AK. Light scattering sensor for direct identification of colonies of Escherichia coli serogroups O26, O45, O103, O111, O121, O145 and O157. PLoS One 2014; 9:e105272. [PMID: 25136836 PMCID: PMC4138183 DOI: 10.1371/journal.pone.0105272] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 07/18/2014] [Indexed: 12/16/2022] Open
Abstract
Background Shiga-toxin producing Escherichia coli (STEC) have emerged as important foodborne pathogens, among which seven serogroups (O26, O45, O103, O111, O121, O145, O157) are most frequently implicated in human infection. The aim was to determine if a light scattering sensor can be used to rapidly identify the colonies of STEC serogroups on selective agar plates. Methodology/Principal Findings Initially, a total of 37 STEC strains representing seven serovars were grown on four different selective agar media, including sorbitol MacConkey (SMAC), Rainbow Agar O157, BBL CHROMagarO157, and R&F E. coli O157:H7, as well as nonselective Brain Heart Infusion agar. The colonies were scanned by an automated light scattering sensor, known as BARDOT (BActerial Rapid Detection using Optical scattering Technology), to acquire scatter patterns of STEC serogroups, and the scatter patterns were analyzed using an image classifier. Among all of the selective media tested, both SMAC and Rainbow provided the best differentiation results allowing multi-class classification of all serovars with an average accuracy of more than 90% after 10–12 h of growth, even though the colony appearance was indistinguishable at that early stage of growth. SMAC was chosen for exhaustive scatter image library development, and 36 additional strains of O157:H7 and 11 non-O157 serovars were examined, with each serogroup producing unique differential scatter patterns. Colony scatter images were also tested with samples derived from pure and mixed cultures, as well as experimentally inoculated food samples. BARDOT accurately detected O157 and O26 serovars from a mixed culture and also from inoculated lettuce and ground beef (10-h broth enrichment +12-h on-plate incubation) in the presence of natural background microbiota in less than 24 h. Conclusions BARDOT could potentially be used as a screening tool during isolation of the most important STEC serovars on selective agar plates from food samples in less than 24 h.
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Affiliation(s)
- Yanjie Tang
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America
| | - Huisung Kim
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Atul K. Singh
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America
| | - Amornrat Aroonnual
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America
| | - Euiwon Bae
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Bartek Rajwa
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America
| | - Pina M. Fratamico
- USDA-ARS, Eastern Regional Research Center, Wyndmoor, Pennsylvania, United States of America
| | - Arun K. Bhunia
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America
- Department of Comparative Pathobiology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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14
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Baltasar P, Milton S, Swecker W, Elvinger F, Ponder M. Shiga toxin-producing Escherichia coli distribution and characterization in a pasture-based cow-calf production system. J Food Prot 2014; 77:722-31. [PMID: 24780325 DOI: 10.4315/0362-028x.jfp-13-420] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Shiga toxin-producing Escherichia coli (STEC) strains are commonly found in cattle gastrointestinal tracts. In this study, prevalence and distribution of E. coli virulence genes (stx1, stx2, hlyA, and eaeA) were assessed in a cow-calf pasture-based production system. Angus cows (n = 90) and their calves (n = 90) were kept in three on-farm locations, and fecal samples were collected at three consecutive times (July, August, and September 2011). After enrichment of samples, stx1, stx2, eaeA, and hlyA were amplified and detected with a multiplex PCR (mPCR) assay. Fecal samples positive for stx genes were obtained from 93.3% (84 of 90) of dams and 95.6% (86 of 90) of calves at one or more sampling times. Age class (dam or calf), spatial distribution of cattle (farm locations B, H, K), and sampling time influenced prevalence and distribution of virulence genes in the herd. From 293 stx-positive fecal samples, 744 E. coli colonies were isolated. Virulence patterns of isolates were determined through mPCR assay: stx1 was present in 41.9% (312 of 744) of the isolates, stx2 in 6.5% (48 of 744), eaeA in 4.2% (31 of 744), and hlyA in 2.4% (18 of 744). Prevalence of non-O157 STEC was high among the isolates: 33.8% (112 of 331) were STEC O121, 3.6% (12 of 331) were STEC O103, and 1.8% (6 of 331) were STEC O113. One isolate (0.3%) was identified as STEC O157. Repetitive element sequence-based PCR (rep-PCR) fingerprinting was used to study genetic diversity of stx-positive E. coli isolates. Overall, rep-PCR fingerprints were highly similar, supporting the hypothesis that strains are transmitted between animals but not necessarily from a dam to its calf. Highly similar STEC isolates were obtained at each sampling time, but isolates obtained from dams were more diverse than those from calves, suggesting that strain differences in transference may exist. Understanding the transfer of E. coli from environmental and animal sources to calves may aid in developing intervention strategies to reduce E. coli colonization of young cattle.
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Affiliation(s)
- Patrícia Baltasar
- Department of Population Health Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Stewart Milton
- Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - William Swecker
- Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - François Elvinger
- Department of Population Health Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Monica Ponder
- Department of Food Science and Technology, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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Svoboda AL, Dudley EG, DebRoy C, Mills EW, Cutter CN. Presence of Shiga Toxin–ProducingEscherichia coliO-Groups in Small and Very-Small Beef-Processing Plants and Resulting Ground Beef Detected by a Multiplex Polymerase Chain Reaction Assay. Foodborne Pathog Dis 2013; 10:789-95. [DOI: 10.1089/fpd.2012.1445] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Amanda L. Svoboda
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania
| | - Edward G. Dudley
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania
| | - Chitrita DebRoy
- E. coli Reference Center, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Edward W. Mills
- Department of Animal Science, The Pennsylvania State University, University Park, Pennsylvania
| | - Catherine N. Cutter
- Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania
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16
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Luchansky JB, Porto-Fett ACS, Shoyer BA, Phillips J, Chen V, Eblen DR, Cook LV, Mohr TB, Esteban E, Bauer N. Fate of Shiga toxin-producing O157:H7 and non-O157:H7 Escherichia coli cells within refrigerated, frozen, or frozen then thawed ground beef patties cooked on a commercial open-flame gas or a clamshell electric grill. J Food Prot 2013; 76:1500-12. [PMID: 23992494 DOI: 10.4315/0362-028x.jfp-12-432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Both high-fat and low-fat ground beef (percent lean:fat = ca. 70:30 and 93:7, respectively) were inoculated with a 6-strain cocktail of non-O157:H7 Shiga toxin-producing Escherichia coli (STEC) or a five-strain cocktail of E. coli O157:H7 (ca. 7.0 log CFU/g). Patties were pressed (ca. 2.54 cm thick, ca. 300 g each) and then refrigerated (4°C, 18 to 24 h), or frozen (-18°C, 3 weeks), or frozen (-18°C, 3 weeks) and then thawed (4°C for 18 h or 21°C for 10 h) before being cooked on commercial gas or electric grills to internal temperatures of 60 to 76.6°C. For E. coli O157:H7, regardless of grill type or fat level, cooking refrigerated patties to 71.1 or 76.6°C decreased E. coli O157:H7 numbers from an initial level of ca. 7.0 log CFU/g to a final level of ≤1.0 log CFU/g, whereas decreases to ca. 1.1 to 3.1 log CFU/g were observed when refrigerated patties were cooked to 60.0 or 65.5°C. For patties that were frozen or freeze-thawed and cooked to 71.1 or 76.6°C, E. coli O157:H7 numbers decreased to ca. 1.7 or ≤0.7 log CFU/g. Likewise, pathogen numbers decreased to ca. 0.7 to 3.7 log CFU/g in patties that were frozen or freeze-thawed and cooked to 60.0 or 65.5°C. For STEC, regardless of grill type or fat level, cooking refrigerated patties to 71.1 or 76.6°C decreased pathogen numbers from ca. 7.0 to ≤0.7 log CFU/g, whereas decreases to ca. 0.7 to 3.6 log CFU/g were observed when refrigerated patties were cooked to 60.0 or 65.5°C. For patties that were frozen or freeze-thawed and cooked to 71.1 or 76.6°C, STEC numbers decreased to a final level of ca. 1.5 to ≤0.7 log CFU/g. Likewise, pathogen numbers decreased from ca. 7.0 to ca. 0.8 to 4.3 log CFU/g in patties that were frozen or freeze-thawed and cooked to 60.0 or 65.5°C. Thus, cooking ground beef patties that were refrigerated, frozen, or freeze-thawed to internal temperatures of 71.1 and 76.6°C was effective for eliminating ca. 5.1 to 7.0 log CFU of E. coli O157:H7 and STEC per g.
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Affiliation(s)
- John B Luchansky
- Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
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17
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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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18
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Magwedere K, Dang HA, Mills EW, Cutter CN, Roberts EL, DebRoy C. Incidence of Shiga toxin–producing Escherichia coli strains in beef, pork, chicken, deer, boar, bison, and rabbit retail meat. J Vet Diagn Invest 2013; 25:254-8. [DOI: 10.1177/1040638713477407] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The objective of the current study was to determine the incidence of contamination by the top 7 Shiga toxin–producing Escherichia coli (STEC) O-groups, responsible for the majority of E. coli infections in human beings, in retail meat from different animal species. Samples from ground beef ( n = 51), ground pork ( n = 16), ground chicken ( n = 16), and game meat (deer, wild boar, bison, and rabbit; n = 55) were collected from retail vendors for the detection of 7 STEC O-groups (O26, O45, O103, O111, O121, O145, and O157). Meat samples were tested by using a multiplex polymerase chain reaction assay targeting the wzx gene of O antigen gene clusters of the 7 STEC O-groups. The positive samples were further tested for Shiga toxin genes ( stx1 and stx2). Out of a total of 83 ground beef, pork, and chicken samples, 17 (20%) carried O121, 9 (10%) carried O45, 8 (9%) carried O157, 3 (3%) carried O103, and 1 (1%) carried O145. None of the samples were positive for O26, O111, or the stx gene. All 3 white-tailed deer samples (100%) were positive for O45, O103, or both, 2 (10%) out of 20 red deer samples exhibited the presence of O103, and all 3 bison samples were contaminated with either O121, O145, or O157. One sample from ground deer, contaminated with E. coli O45, carried the stx1 gene. This preliminary investigation illustrates the importance of microbiological testing of pathogens in meat products, as well as the recognized need for increased surveillance and research on foodborne pathogens.
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Affiliation(s)
- Kudakwashe Magwedere
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
| | - Huu Anh Dang
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
| | - Edward W. Mills
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
| | - Catherine N. Cutter
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
| | - Elisabeth L. Roberts
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
| | - Chitrita DebRoy
- Departments of Veterinary and Biomedical Sciences (Dang, Roberts, DebRoy), Pennsylvania State University, University Park, PA
- Animal Science (Magwedere, Mills), Pennsylvania State University, University Park, PA
- Food Science (Cutter), Pennsylvania State University, University Park, PA
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19
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Jeon SJ, Elzo M, DiLorenzo N, Lamb GC, Jeong KC. Evaluation of animal genetic and physiological factors that affect the prevalence of Escherichia coli O157 in cattle. PLoS One 2013; 8:e55728. [PMID: 23405204 PMCID: PMC3566006 DOI: 10.1371/journal.pone.0055728] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/29/2012] [Indexed: 11/19/2022] Open
Abstract
Controlling the prevalence of Escherichia coli O157 in cattle at the pre-harvest level is critical to reduce outbreaks of this pathogen in humans. Multilayers of factors including the environmental and bacterial factors modulate the colonization and persistence of E. coli O157 in cattle that serve as a reservoir of this pathogen. Here, we report animal factors contributing to the prevalence of E. coli O157 in cattle. We observe the lowest number of E. coli O157 in Brahman breed when compared with other crosses in an Angus-Brahman multibreed herd, and bulls excrete more E. coli O157 than steers in the pens where cattle were housed together. The presence of super-shedders, cattle excreting >10(5) CFU/rectal anal swab, increases the concentration of E. coli O157 in the pens; thereby super-shedders enhance transmission of this pathogen among cattle. Molecular subtyping analysis reveal only one subtype of E. coli O157 in the multibreed herd, indicating the variance in the levels of E. coli O157 in cattle is influenced by animal factors. Furthermore, strain tracking after relocation of the cattle to a commercial feedlot reveals farm-to-farm transmission of E. coli O157, likely via super-shedders. Our results reveal high risk factors in the prevalence of E. coli O157 in cattle whereby animal genetic and physiological factors influence whether this pathogen can persist in cattle at high concentration, providing insights to intervene this pathogen at the pre-harvest level.
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Affiliation(s)
- Soo Jin Jeon
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Mauricio Elzo
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Nicolas DiLorenzo
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
- North Florida Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Marianna, Florida, United States of America
| | - G. Cliff Lamb
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
- North Florida Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Marianna, Florida, United States of America
| | - Kwang Cheol Jeong
- Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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20
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Hayek SA, Ibrahim SA. Antimicrobial Activity of Xoconostle Pears (Opuntia matudae) against Escherichia coli O157:H7 in Laboratory Medium. Int J Microbiol 2012; 2012:368472. [PMID: 22934117 PMCID: PMC3426250 DOI: 10.1155/2012/368472] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 06/27/2012] [Indexed: 11/18/2022] Open
Abstract
The objective of this study was to investigate the antimicrobial activity of xoconostle pears (Opuntia matudae) against Escherichia coli O157:H7. Xoconostle pears were sliced, blended, and centrifuged. The supernatant was then filtered using a 0.45 μm filter to obtain direct extract. Direct extract of xoconostle pears was tested against four strains of E. coli O157:H7 in brain heart infusion (BHI) laboratory medium using growth over time and agar well diffusion assays. Our results showed that direct extract of xoconostle pears had a significant (P < 0.05) inhibitory effect at 4, 6, and 8% (v/v) concentrations and complete inhibitory effect at 10% (v/v) during 8 h of incubation at 37°C. Minimum inhibitory volume (MIV) was 400 μL mL(-1) (v/v) and minimum lethal volume (MLV) was 650 μL mL(-1) (v/v). The inhibitory effect of xoconostle pears found to be concentration dependent and not strain dependent. Thus, xoconostle pears extract has the potential to inhibit the growth of E. coli O157:H7 and could provide a natural means of controlling pathogenic contamination, thereby mitigating food safety risks.
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Affiliation(s)
| | - Salam A. Ibrahim
- Food Microbiology and Biotechnology Laboratory, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA
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21
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Bai J, Paddock ZD, Shi X, Li S, An B, Nagaraja TG. Applicability of a Multiplex PCR to Detect the Seven Major Shiga Toxin–ProducingEscherichia coliBased on Genes That Code for Serogroup-Specific O-Antigens and Major Virulence Factors in Cattle Feces. Foodborne Pathog Dis 2012; 9:541-8. [DOI: 10.1089/fpd.2011.1082] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jianfa Bai
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Zachary D. Paddock
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Xiaorong Shi
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Shubo Li
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
- Liaoning Center for Animal Epidemic Disease Control and Prevention, Shenyang, Liaoning, China
| | - Baoyan An
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
| | - Tiruvoor G. Nagaraja
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
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22
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Paddock Z, Shi X, Bai J, Nagaraja T. Applicability of a multiplex PCR to detect O26, O45, O103, O111, O121, O145, and O157 serogroups of Escherichia coli in cattle feces1. Vet Microbiol 2012; 156:381-8. [DOI: 10.1016/j.vetmic.2011.11.017] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
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23
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Rapid detection of the top six non-O157 Shiga toxin-producing Escherichia coli O groups in ground beef by flow cytometry. J Clin Microbiol 2012; 50:2137-9. [PMID: 22493328 DOI: 10.1128/jcm.00137-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rapid, sensitive, and highly specific flow-cytometric assays were developed for the detection of the top six non-O157 Shiga toxin-producing Escherichia coli (STEC) O groups in ground beef. The analytical sensitivity of the assays was 2 × 10(3) target cells in a bacterial mixture of 10(5) CFU/ml, and the limit of detection in ground beef was 1 to 10 CFU following 8 h of enrichment. The assays may be utilized for rapid detection of STEC O groups in meat.
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24
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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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25
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López-Campos G, Martínez-Suárez JV, Aguado-Urda M, López-Alonso V. Detection, Identification, and Analysis of Foodborne Pathogens. SPRINGERBRIEFS IN FOOD, HEALTH, AND NUTRITION 2012. [DOI: 10.1007/978-1-4614-3250-0_2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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