Export file:


  • RIS(for EndNote,Reference Manager,ProCite)
  • BibTex
  • Text


  • Citation Only
  • Citation and Abstract

Incidence of Top 6 shiga toxigenic Escherichia coli within two Ontario beef processing facilities: Challenges in screening and confirmation testing

1 Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
2 Agriculture and Food Laboratory, Laboratory Services Division, University of Guelph, Guelph, Ontario N1H 8H7, Canada

Topical Section: Pathogenic microorganisms and human health

The incidence of the Top 6 STEC serotypes was determined in two beef slaughter houses. In total, 328 samples were taken of hides, de-hided carcasses and the plant environment. Samples were enriched in Tryptic Soy Broth containing novobiocin then screened using RT-PCR GeneDiskÒ system that targeted stx, eae and wzx genes. It was found that 92.5% (172 of 186) of the hide samples. 72.5% (29 of 40) de-hided samples and 84.3% (86 of 102) of the environmental samples returned presumptive positive results. Serotypes O103, O45 and O121 were most commonly encountered although all the Top 6 serotypes were represented within individual samples. However, attempts to recover the Top 6 serotypes by culturing proved unsuccessful despite screening up to 20 colonies per CHROMAgar® plate of enriched sample. The reasons for the discrepancy between the RT-PCR and culture methods were found to be due to low levels of the target in enriched samples, presence of virulence factors in different cells and also the transient retention of stx. With regards the latter it was found that strains harboring a full set of virulence factors (eae, stx) were more common in grown cultures held post-incubation at 4 °C for 14 days. Moreover, no stx gene was recovered when isolates were sub-cultured on TSA but was present in the same strains grown on CHROMAgar®. In total 39 STEC isolates were recovered with the majority harboring stx1, stx2, eae and hylA. Only 3 of the isolates had stable complement of virulence factors and were identified as O172:H28, O76:H7 and O187:H52. Although no Top 6 STEC were isolated the presence of virulent strains on carcasses with the potential to cause Hemolytic Uremic Syndrome is of concern. The significance of those STEC that transiently harbor virulence factors is unclear although clearly impacts on diagnostic performance robustness when screening for the Top 6 non-O157 STEC.
  Article Metrics


1. Warriner K (2011) IUFoST Scientific Information Bulletin. Shiga toxin producing Escherichia coli: Germany 2011 Escherichia coli O104:H4 outbreak linked to sprouted seeds.

2. Scallan E, Mahon BE, Hoekstra RM, et al. (2013) Estimates of Illnesses, Hospitalizations and Deaths Caused by Major Bacterial Enteric Pathogens in Young Children in the United States. Pediatr Infect Dis J 32: 217–221.

3. Scallan E, Jones TF, Cronquist A, et al. (2006) Factors associated with seeking medical care and submitting a stool sample in estimating the burden of foodborne illness. Foodborne Pathogens Dis 3: 432–438.

4. Scallan E, Hoekstra RM, Angulo FJ, et al. (2011) Foodborne Illness Acquired in the United States-Major Pathogens. Emerg Infect Dis 17: 7–15.    

5. Parsons BD, Zelyas N, Berenger BM, et al (2016) Detection, Characterization, and Typing of Shiga Toxin-Producing Escherichia coli. Front Microbiol 7: 478.

6. Bosilevac JM, Koohmaraie M (2011) Prevalence and Characterization of Non-O157 Shiga Toxin-Producing Escherichia coli Isolates from Commercial Ground Beef in the United States. Appl Environ Microbiol 77: 2103–2112.

7. Fuller CA, Pellino CA, Flagler MJ, et al (2011) Shiga Toxin Subtypes Display Dramatic Differences in Potency. Infect Immun 79: 1329–1337.

8. McGannon CM, Fuller CA, Weiss AA (2011) Different Classes of Antibiotics Differentially Influence Shiga Toxin Production. Antimicrob Ag Chemoth 54: 3790–3798.

9. Chui L, Li V, Fach P, et al. (2015) Molecular Profiling of Escherichia coli O157:H7 and Non-O157 Strains Isolated from Humans and Cattle in Alberta, Canada. J Clin Microbiol 53: 986–990.

10. Food Safety Inspection Service (2012). Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products. Docket FSIS-2010-0023) Available from: http://www.fsis.usda.gov /OPPDE/rdad/FRPubs/ 2010-0023FRN.pdf (Accessed July 2016).

11. Wasilenko JL, Fratamico PM, Sommers C, et al. (2014) Detection of Shiga toxin-producing Escherichia coli (STEC) O157:H7, O26, O45, O1O3, O111, O121, and O145, and Salmonella in retail raw ground beef using the DuPont (TM) BAX (R) system. Front Cell Infect Microbiol 4: 81.

12. Hussein HS, Bollinger LM (2005) Prevalence of Shiga toxin-producing Escherichia coli in beef cattle. J Food Protect 68: 2224–2241.

13. Johnson KE, Thorpe CM, Sears CL (2006) The emerging clinical importance of non-O157 Shiga toxin - Producing Escherichia coli. Clin Infect Dis 43: 1587–1595.

14. Mathusa EC, Yuhuan C, Enache E, et al. (2010) Non-O157 Shiga toxin-producing Escherichia coli in foods. J Food Protect 73: 1721–1736.

15. Renter DG, Checkley SL, Campbell J, et al (2004) Shiga toxin-producing Escherichia coli in the feces of Alberta feedlot cattle. Can J Vet Res 68: 150–153.

16. Anklam KS, Kanankege KST, Gonzales TK (2012) Rapid and reliable detection of Shiga toxin-producing Escherichia coli by real-time multiplex PCR. J Food Protect 75: 643–650.

17. Paton AW, Paton JC (2002) Direct detection and characterization of Shiga toxigenic Escherichia coli by multiplex PCR for stx(1), stx(2), eae, ehxA, and saa. J Clin Microbiol 40: 271–274.    

18. Conrad CC, Stanford K, McAllister TA, et al. (2014) Further development of sample preparation and detection methods for O157 and the top 6 non-O157 STEC serogroups in cattle feces. J Microbiol Meth 105: 22–30.

19. Hofer E, Stephan R, Reist M, et al. (2012) Application of a Real-Time PCR-Based System for Monitoring of O26, O103, O111, O145 and O157 Shiga Toxin-Producing Escherichia coli in Cattle at Slaughter. Zoonoses and Public Health 59: 408–415.

20. Bosilevac JM, Guerini MN, Brichta-Harhay DM, et al. (2007) Microbiological characterization of imported and domestic boneless beef trim used for ground beef. J Food Protect 70: 440–449.

21. Arthur TM, Barkocy-Gallagher GA, Rivera-Betancourt M, et al. (2002) Prevalence and characterization of non-O157 Shiga toxin-producing Escherichia coli on carcasses in commercial beef cattle processing plants. Appl Environ Microbiol 68: 4847–4852.    

22. Cooley MB, Jay-Russell M, Atwill ER, et al. (2013) Development of a Robust Method for Isolation of Shiga Toxin-Positive Escherichia coli (STEC) from Fecal, Plant, Soil and Water Samples from a Leafy Greens Production Region in California. Plos One 8: e65716.    

23. Verhaegen B, Van Damme I, Heyndrickx M, et al. (2016) Evaluation of detection methods for non-O157 Shiga toxin-producing Escherichia coli from food. Int J Food Microbiol 219: 64–70.

24. Versalovic J, Koeuth T, Lupski JR (1991). Distribution of repetative DNA sequences in eubacteria and application to fingerprinting bacterial genomes. Nucleic Acids Res 19: 6823–6831.

25. Karama M, Gyles CL (2013) Virulence Profiling of Shiga Toxin-Producing Escherichia coli O111:NM Isolates from Cattle. Appl Environ Microbiol 79: 4164–4165.    

26. Paddock Z, Shi X, Bai J, Nagaraja TG (2012) Applicability of a multiplex PCR to detect O26, O45, O103, O111, O121, O145, and O157 serogroups of Escherichia coli in cattle feces. Vet Microbiol 156: 381–388.

27. Imamovic L, Tozzoli R, Michelacci V, et al. (2010) OI-57, a Genomic Island of Escherichia coli O157, Is Present in Other Seropathotypes of Shiga Toxin-Producing E-coli Associated with Severe Human Disease. Infect Immun 78: 4697–4704.    

28. Imamovic L, Balleste E, Jofre J, et al. (2010) Quantification of Shiga Toxin-Converting Bacteriophages in Wastewater and in Fecal Samples by Real-Time Quantitative PCR. Appl Environ Microbiol 76: 5693–5701.    

29. Quiros P, Martinez-Castillo A, Muniesa M (2015) Improving Detection of Shiga Toxin-Producing Escherichia coli by Molecular Methods by Reducing the Interference of Free Shiga Toxin-Encoding Bacteriophages. Appl Environ Microbiol 81: 415–421.

30. Eichhorn I, Heidemanns K, Semmler T, et al. (2015) Highly Virulent Non-O157 Entero-hemorrhagic Escherichia coli (EHEC) Serotypes Reflect Similar Phylogenetic Lineages, Providing New Insights into the Evolution of EHEC. Appl Environ Microbiol 81: 7041–7047.

31. Bielaszewska M, Prager R, Koeck R, et al. (2007) Shiga toxin gene loss and transfer in vitro and in vivo during enterohemorrhagic Escherichia coli O26 infection in humans. Appl Environ Microbiol 73: 3144–3150.    

32. Martinez-Castillo A, Muniesa M (2014) Implications of free Shiga toxin-converting bacteriophages occurring outside bacteria for the evolution and the detection of Shiga toxin-producing Escherichia coli. Front Cell Infect Microbiol 4: 46.

33. Delannoy S, Mariani-Kurkdjian P, Bonacorsi S, et al. (2015) Characteristics of Emerging Human-Pathogenic Escherichia coli O26:H11 Strains Isolated in France between 2010 and 2013 and Carrying the stx(2d) Gene Only. J Clin Microbiol 53: 486–492.

34. Joris M-A, Verstraete K, De Reu K, et al. (2011) Loss of vtx Genes after the First Subcultivation Step of Verocytotoxigenic Escherichia coli O157 and Non-O157 during Isolation from Naturally Contaminated Fecal Samples. Toxins 3: 672–677.

Copyright Info: © 2016, Keith Warriner, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

Download full text in PDF

Export Citation

Article outline

Show full outline
Copyright © AIMS Press All Rights Reserved