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2010-2011 Bacterial Pathogens and Generic E. coli in Leafy Vegetables


The Food Safety Action Plan (FSAP) aims to modernize and enhance Canada's food safety system in order to better protect Canadians from unsafe food and ultimately reduce the occurrence of foodborne illness.

In recent years, leafy vegetables have been reported to be responsible for outbreaks of foodborne illness worldwide. The Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO) has ranked leafy vegetables as the highest priority of concern in terms of microbiological hazards among fresh fruits and vegetables. Leafy vegetables can become contaminated with various foodborne pathogens during production, harvest, post-harvest handling, processing, packaging, and distribution. The presence of pathogens in leafy vegetables creates a potential risk for foodborne illness as leafy vegetables are often consumed raw. The disease causing bacterial pathogens Escherichia coli (E. coli) O157:H7 and Salmonella have accounted for the majority of the outbreaks associated with leafy vegetables.

Considering these factors and their relevance to Canadians, leafy vegetables have been selected as one of the priority commodity groups of fresh fruits and vegetables for enhanced surveillance under the FSAP. Over the course of a five-year baseline study (2008/09 - 2012/13), approximately 10,000 leafy vegetable samples were collected from Canadian retail locations and tested for various pathogens of concern.

The main objectives of the 2010/11 survey were to generate baseline surveillance data on bacterial pathogens Salmonella, Shigella, Campylobacter, Listeria monocytogenes, E. coli O157 and other verotoxigenic E. coli (VTEC), as well as on the indicator of fecal contamination generic E. coli, for a variety of leafy vegetables available in the Canadian market. A total of 2596 leafy vegetable samples from various countries and production practices were collected and analyzed for one or more bacterial pathogen(s) or indicator of interest. The results indicate that bacterial pathogens were not detected in any of the leafy vegetable samples. Two samples were found to be unsatisfactory due to high levels of generic E. coli (> 1000 CFU/g). These two sample results triggered appropriate follow-up activities by the Canadian Food Inspection Agency (CFIA), though no recalls were required. In addition, elevated levels of generic E. coli (> 100 and ≤ 1000 CFU/g) were found in eight other samples. These samples were assessed as investigative and further evaluation resulted in no immediate follow-up activities. These results suggest that the vast majority of fresh leafy vegetables in the Canadian market sampled during this survey were produced under Good Agricultural Practices (GAPs) and Good Manufacturing Practices (GMPs).

The CFIA regulates and provides oversight to the industry, works with provinces and territories, and promotes safe handling of foods throughout the food production chain. However, it is important to note that the food industry and retail sectors in Canada are ultimately responsible for the food they produce and sell, while individual consumers are responsible for the safe handling of the food they have in their possession. Moreover, general advice for the consumer on the safe handling of foods is widely available. The CFIA will continue its surveillance activities and inform stakeholders of its findings.

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