Verotoxigenic Escherichia coli Laboratory

VTEC bacteria

Research Scientist

Dr. Alexander Gill,
Bureau of Microbial Hazards, Health Canada

Research Technical Support: Mahdid Meymandy

Research Activity

Escherichia coli are a widely distributed species of bacteria that that can commonly be isolated from the intestinal tract of animals and environmental sources. The majority of E. coli strains are non-pathogenic commensals, but a variety of pathogenic strains also exist. The most important E. coli pathogen in Canada and North America are verotoxigenic E. coli (VTEC). VTEC are distinguished from other E. coli by the production of one or more verotoxins. The terms shiga toxin producing E. coli (STEC) and enterohemorrhagic E. coli (EHEC) are also used for these pathogens. VTEC infection can occur following ingestion of contaminated food or water and can result in serious, life threatening illness. The best known VTEC serogroup is E. coli O157:H7, since this serotype has been responsible for a number of major outbreaks in North America. Other important VTEC serogroups include, O26, O45, O103, O111, O121 and O145.

Research at the VTEC laboratory aims to protect Canadians from VTEC by improving methods for the detection of VTEC and identifying methods for reducing exposure to VTEC. Traditionally, the detection of VTEC in foods has focused on a small number of serotypes associated with serious illness and major outbreaks, but an increasing variety of VTEC serotypes are associated with human illness. To improve the capability of regulatory and public health authorities to respond to VTEC, we are conducting research to identify molecular markers with which to identify VTEC, developing serotype independent molecular methods for the detection of VTEC and culture based methods for their isolation.

A significant proportion of VTEC outbreaks have been associated with he ingestion of contaminated salad greens. Since these products are consumed uncooked, reducing contamination is an important strategy in protecting consumers. The VTEC laboratory is engaged in a collaborative project with Agriculture and Agri-Food Canada scientists to understand VTEC contamination and survival on salad greens so that interventions to prevent contamination can be developed.

High pressure pasteurisation of foods is an emerging food processing technology in which bacterial cells are killed by treatment with hydrostatic pressures in the range of 3000 to 6000 atmospheres. The VTEC Laboratory is engaged in research on the application of high pressure pasteurisation to improve the safety of ready to meat products.

Current Research Activity

  1. Development of molecular and culture based methods for the detection and isolation of VTEC in foods.
  2. Molecular characterization of VTEC to identify virulence factors.
  3. Identification of contamination sources and the survival of VTEC on salad greens during cultivation and processing.
  4. The application of High Pressure Pasteurization to control VTEC and other food-borne pathogens on ready-to-eat meats.
  5. The survival of Enteric pathogens in compost.


  1. Canadian VTEC Network
  2. Agence nationale de sécurité sanitaire, Laboratoire de sécurité des aliments de Maisons-Alfort, Maisons-Alfort, France
  3. Department of Agricultural, Food and Nutritional Science, University of Alberta
  4. Department of Food Science, University of Manitoba

Recent Publications

Bugarel, M., Beutin, L., Martin, A., Gill, A., and Fach, P. 2010. Micro-array for the detection of Shiga toxin-producing Escherichia coli (STEC) seropathotypes associated with Hemorrhagic Colitis and Hemolytic Uremic Syndrome in humans. International Journal of Food Microbiology. 142:318-329.

Gill, A.O. and Gill, C.O. 2010. Non-O157 Verotoxigenic Escherichia coli and Beef: A Canadian Perspective. Canadian Journal of Veterinary Research. 74:161-169.

Gill, A.O. and Gill, C.O. 2009. Packaging and the Shelf Life of Fresh Red and Poultry Meats. Chapter 14, In Food Packaging and Shelf Life: A Practical Guide. Edited by G.L. Robertson. Taylor & Francis Group, LLC, Boca Raton, FL. pp. 259-277.

Gill, A.O. and Ramaswamy, H.S. 2008. The application of high pressure processing to kill Escherichia coli O157 in ready to eat meats. Journal of Food Protection. 71(11):2182-2189.

Gill, A.O. and Holley, R.A. 2006. Inhibition of membrane bound ATPases of Escherichia coli and Listeria monocytogenes by plant oil aromatics. International Journal of Food Microbiology. 111:170-174.

Gill, A.O. and Holley, R.A. 2006. Disruption of Escherichia coli, Listeria monocytogenes and Lactobacillus sakei cellular membranes by plant oil aromatics. International Journal of Food Microbiology. 108:1-9.

Gill, A.O. and Gill, C.O. 2005. Preservative packaging for fresh meats, poultry and fin fish. Chapter 13, In Innovation in Food Packaging. Edited by J.H. Han. Elsevier Academic Press, Amsterdam. pp. 204-226.

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