Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada

Shiga toxin-producing Escherichia coli (STEC) are potentially pathogenic E. coli that may cause mild to severe gastrointestinal illnesses. STEC-contaminated foods of animal origin have been the most frequently implicated sources of foodborne outbreaks. A multiyear (2016 to 2021) targeted survey was...

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Main Authors: Helen Zhang, Etsuko Yamamoto, Austin Markell, Catherine Carrillo, Annie Locas
Format: Article
Language:English
Published: Elsevier 2025-04-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X25000353
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author Helen Zhang
Etsuko Yamamoto
Austin Markell
Catherine Carrillo
Annie Locas
author_facet Helen Zhang
Etsuko Yamamoto
Austin Markell
Catherine Carrillo
Annie Locas
author_sort Helen Zhang
collection DOAJ
description Shiga toxin-producing Escherichia coli (STEC) are potentially pathogenic E. coli that may cause mild to severe gastrointestinal illnesses. STEC-contaminated foods of animal origin have been the most frequently implicated sources of foodborne outbreaks. A multiyear (2016 to 2021) targeted survey was conducted to investigate the prevalence of STEC in retail ground meats (beef, veal, and lamb). Samples were screened for the presence of Shiga toxin genes (stx) to identify presumptive samples, followed by culture and molecular confirmation of isolates to confirm the presence of stx genes and subsequent characterization by whole-genome-sequencing (WGS) for O serogroup and virulence genes (e.g., stx, eae, aggR). A total of 175 STEC strains were isolated from a total of 148 samples where the presence of viable STEC was confirmed out of 2,398 ground meat samples. This represented 1.2% (7/589 positive, 8 unique strains) of the beef samples, 4.7% (58/1,241 positive, 67 unique strains) of the veal samples, and 14.6% (83/568 positive, 100 unique strains) of the lamb samples. The intimin virulence gene, eae, was identified in the STEC strains of veal origin (9/67, 13.4%) only and were classified as belonging to risk level 1 (1/67), level 3 (2/67), and level 4 (6/67) according to the FAO/WHO risk categories. Risk level 2 STEC strains were of beef (2/8, 25.0%), veal (8/67, 11.9%), and lamb (1/100, 1.0%) origin. The majority of the STEC strains, 75.0% (6/8) of the beef, 67.2% (45/67) of the veal, and 94.0% (94/100) of the lamb STEC strains were classified as risk level 5 (lowest level) of the FAO/WHO risk categories. This study’s findings indicate that the current food safety control measures implemented for ground meats in Canada are effective at maintaining an acceptable level of possible contamination with STEC strains associated with severe clinical outcomes. Continued application of effective control measures and safe food handling practices by consumers will minimize the potential risk of foodborne infections from raw ground meats.
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spelling doaj-art-656d757c097b4b6487170d8632c1769e2025-08-20T02:12:19ZengElsevierJournal of Food Protection0362-028X2025-04-0188510048310.1016/j.jfp.2025.100483Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in CanadaHelen Zhang0Etsuko Yamamoto1Austin Markell2Catherine Carrillo3Annie Locas4Food Safety Science Directorate, Science Branch, Canadian Food Inspection Agency, 1400 Merivale Road, Ottawa, Ontario K1A 0Y9, Canada; Corresponding author at: Food Safety Science Directorate, Science Branch, Canadian Food Inspection Agency, 1400 Merivale Road, Ottawa, Ontario K1A 0Y9, Canada.Food Safety Science Directorate, Science Branch, Canadian Food Inspection Agency, 1400 Merivale Road, Ottawa, Ontario K1A 0Y9, CanadaFood Safety Science Directorate, Science Branch, Canadian Food Inspection Agency, 1400 Merivale Road, Ottawa, Ontario K1A 0Y9, CanadaResearch and Development, Ottawa Laboratory (Carling), Canadian Food Inspection Agency, Bldg 22, CEF 960 Carling Avenue, Ottawa, Ontario K1A 0Y9, CanadaFood Safety Science Directorate, Science Branch, Canadian Food Inspection Agency, 1400 Merivale Road, Ottawa, Ontario K1A 0Y9, CanadaShiga toxin-producing Escherichia coli (STEC) are potentially pathogenic E. coli that may cause mild to severe gastrointestinal illnesses. STEC-contaminated foods of animal origin have been the most frequently implicated sources of foodborne outbreaks. A multiyear (2016 to 2021) targeted survey was conducted to investigate the prevalence of STEC in retail ground meats (beef, veal, and lamb). Samples were screened for the presence of Shiga toxin genes (stx) to identify presumptive samples, followed by culture and molecular confirmation of isolates to confirm the presence of stx genes and subsequent characterization by whole-genome-sequencing (WGS) for O serogroup and virulence genes (e.g., stx, eae, aggR). A total of 175 STEC strains were isolated from a total of 148 samples where the presence of viable STEC was confirmed out of 2,398 ground meat samples. This represented 1.2% (7/589 positive, 8 unique strains) of the beef samples, 4.7% (58/1,241 positive, 67 unique strains) of the veal samples, and 14.6% (83/568 positive, 100 unique strains) of the lamb samples. The intimin virulence gene, eae, was identified in the STEC strains of veal origin (9/67, 13.4%) only and were classified as belonging to risk level 1 (1/67), level 3 (2/67), and level 4 (6/67) according to the FAO/WHO risk categories. Risk level 2 STEC strains were of beef (2/8, 25.0%), veal (8/67, 11.9%), and lamb (1/100, 1.0%) origin. The majority of the STEC strains, 75.0% (6/8) of the beef, 67.2% (45/67) of the veal, and 94.0% (94/100) of the lamb STEC strains were classified as risk level 5 (lowest level) of the FAO/WHO risk categories. This study’s findings indicate that the current food safety control measures implemented for ground meats in Canada are effective at maintaining an acceptable level of possible contamination with STEC strains associated with severe clinical outcomes. Continued application of effective control measures and safe food handling practices by consumers will minimize the potential risk of foodborne infections from raw ground meats.http://www.sciencedirect.com/science/article/pii/S0362028X25000353eae geneGround beefGround lambGround vealShiga toxin-producing Escherichia coli (STEC)stx gene
spellingShingle Helen Zhang
Etsuko Yamamoto
Austin Markell
Catherine Carrillo
Annie Locas
Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
Journal of Food Protection
eae gene
Ground beef
Ground lamb
Ground veal
Shiga toxin-producing Escherichia coli (STEC)
stx gene
title Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
title_full Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
title_fullStr Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
title_full_unstemmed Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
title_short Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) and Risk Characterization Based on Virulence Genes in Retail Raw Ground Meat of Beef, Veal, and Lamb in Canada
title_sort prevalence of shiga toxin producing escherichia coli stec and risk characterization based on virulence genes in retail raw ground meat of beef veal and lamb in canada
topic eae gene
Ground beef
Ground lamb
Ground veal
Shiga toxin-producing Escherichia coli (STEC)
stx gene
url http://www.sciencedirect.com/science/article/pii/S0362028X25000353
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