Escherichia coli O157:H7 – Food
For sampling, follow the instructions found in Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing.
- Ship all foods in containers with hard walls and lids secured in the closed position.
- Shipping containers must be labelled with the submitting organization, unique identifier and contents e.g. FOOD SAMPLES on the outside of the container.
- DO NOT SHIP WITH CLINICAL SPECIMENS. Shipping containers used for food samples should be dedicated to food samples and not be used for other types of environmental samples.
- Ship dry foods and other shelf stable foods at ambient temperature in a closed container.
- Ship frozen foods in an insulated container with sufficient ice packs to maintain the frozen state.
- Ship perishable foods in an insulated container with sufficient cold packs to maintain a temperature as close to 4°C as possible. If ice is used, contain the ice in a manner that does not allow water contact with the samples.
- Submit all food samples to the laboratory as soon as possible.
Test Frequency and Turnaround Time (TAT)
The Escherichia coli O157:H7 test is performed Monday to Saturday.
Turnaround time is up to 9 days.
Results are reported to the submitting health unit as indicated on the requisition, when all analyses are completed.
Food samples that show the presence of bacteria capable of causing food-borne illness are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.
The presence of Escherichia coli O157:H7 is detected by culturing food in non-selective enrichment broth followed by Immunomagnetic Separation (IMS) and isolation on selective agar plates with subsequent biochemical and serological identification. (Public Health Ontario Laboratory Method)
Escherichia coli O157:H7 should be absent from ready to eat foods.