Background: Bacillus cereus has a ubiquitous distribution in the environment and can be isolated from a variety of processed and raw foods. However, its presence in food is not a significant health threat unless it is able to grow and produce enterotoxins. Consumption of food containing as low as 100 viable B. cereus cells/g has resulted in outbreaks of food-borne illnesses and the establishment of specifications for various food ingredients by food manufacturers.
Foods frequently incriminated in outbreaks of B. cereus poisoning include boiled and fried rice, cooked pasta, cooked meats, cooked vegetables, soups, salads, pudding, and vegetable sprouts. It is also often associated with poor food handling and keeping of the food at high temperatures for too long allowing the spores to germinate and the pathogen to multiply. B. cereus strains have been isolated from foods stored at refrigeration temperatures. The spores can spread easily in any environment and be transmitted from person to person.
This method allows for the isolation, identification and enumeration of Bacillus cereus from naturally-contaminated meats, vegetables, dairy products, cereals and dry foods.
Method: Health Canada (MFLP-42)
Turn Around time: 2-3 Business Days
Reported results: number of Bacillus cereus per g or mL of food
SPECIMEN REQUIREMENTS
Specimen Type:Food – indicate if part of a meal, control or follow up.
Container/Kit: Submit 250 grams of food in a sterile plastic sample bag with round wire closure.
Collection information: See Section Sampling under Food Sampling.
Requisition: Complete all fields of the form. See section Forms under Microbiology Sample Sheet.
Sterile bag: See section Form under Requisition for Containers and Supplies.
Preparation prior to transport: Keep refrigerated or frozen.
Shipping Instructions:
- 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.
- 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 dry 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 INFORMATION
The Bacillus cereus count is determined by culture
techniques using the spread plate method with agar plates that are selective
for Bacillus cereus, followed by biochemical identification techniques.
The unsatisfactory level for Bacillus cereus in food is ≥ 104 CFU/gram
(potentially hazardous).