Isolation of Listeria monocytogenes and other Listeria spp. from foods and environmental samples
Background: Listeria monocytogenes is widely recognized as an important cause of human foodborne illness, particularly for persons with heightened immune susceptibility.
Although the number of people infected by food-borne Listeria is comparatively small, this bacterium is one of the leading causes of hospitalizations and death from food-borne illness. It can cause two forms of infection and disease. One can range from mild to intense symptoms of nausea, vomiting, aches, fever, and, sometimes, diarrhea, and usually goes away by itself. The other, more deadly form occurs when the infection spreads through the bloodstream to the nervous system (including the brain), resulting in meningitis and other potentially fatal problems. Pregnant women are more susceptible to Listeria infection than are most other people, and although they generally recover, their foetus or new-born babies usually don’t survive following the infection.
Listeria is hardy and found in many places; it tolerates salty environments and cold temperatures, unlike many other foodborne bacteria. Humans can acquire Listeria infections from consumption of contaminated poultry meat or meat products (pre-cooked and ready-to-eat products), improper/unhygienic food handling practices, or even contaminated water. Listeria cases have been traced back to several foods; for example, raw or under‐pasteurized milk; smoked fish and other seafood; meats, including ready-to-eat deli meats; cheeses (especially soft cheeses); and raw vegetables probably from contaminated soil or water.
This method allows for the isolation and identification of Listeria monocytogenes and other Listeria species from food samples and swabs of food contact surfaces.
Method: Health Canada (MFHPB-30)
Turn Around time: 5 Business Days
Reported results: Negative or Positive
SPECIMEN REQUIREMENTS
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
Listeria should be absent from food or surfaces.