Most cases of B. cereus poisoning are usually mild and self-limiting, so they are rarely recorded and reported, but B. cereus disease is still considered a significant health hazard and a significant challenge for the food processing industry.

Authors in Germany and Norway compiled medical data from 1906 to 2019 and recorded nearly 4,000 cases of B. cereus poisoning, mainly from reports from the United States and Europe.

B. cereus causes two different types of poisoning: (1) the form that causes symptoms mainly of abdominal pain, diarrhea, loose stools without mucus or blood, and may have vomiting; (2) the form that mainly causes vomiting, nausea, and fatigue.

Each type of disease is related to many different influencing factors, different food sources, facilitating the multiplication of bacteria in food or in the intestines, producing different toxins to cause poisoning.

As mentioned, because it is a common, conditionally pathogenic bacteria, B. cereus is easily present in many different types of food and dishes. When encountering unfavorable conditions: dry, hot due to food processing, preparation, and preservation, B. cereus can still exist in spore form. Bacterial spores are quite resistant to disinfection measures: heat, radiation, ultrasound, ion solution, ozone, disinfectant chemicals, low pH; only killed by steaming at 1210C for 20 minutes or drying at 1600C for 1 hour, which is not a common condition in food processing. After cooking, if the dish is left to cool for a few hours before eating, bacterial spores can return to a state of growth and multiplication, at this time B. cereus is not competed by other bacteria, because other bacteria were killed during the previous cooking process. And because it is a conditionally pathogenic and common bacteria, the presence of B.cereus in food must reach a certain concentration to be able to cause disease. Food with a concentration of 1,000 bacteria per gram is considered unsafe, but the dangerous concentration is considered to be 1 million or more.

B. cereus in contaminated food causes disease in two ways: (1) entering the intestine, multiplying to create toxins that cause diarrhea-like poisoning, this type usually has an incubation period of 12-24 hours; (2) the bacteria multiply in food and create toxins that cause vomiting, this type has an incubation period of 0.5-5 hours.

Foods related to diarrhea include: meat, meat products, vegetables, bean sprouts, sauces, mixed cakes, poultry. Foods associated with vomiting include starchy foods such as rice, potatoes, vegetables, fruits, dairy products, fermented bean products (soy sauce, fermented bean curd, tofu), mushrooms

Prevention of B. cereus poisoning is mainly about preserving food after processing. If not eaten immediately, the dish needs to be kept warm above 600C or cold below 40C. Cold food needs to be reheated thoroughly, at least reaching 740C before eating. Ingredients for cold and fermented dishes need to be carefully selected and washed. When poisoning occurs, it is important to pay attention to cleaning and disinfecting the kitchen and processing utensils. Keep the processing area, food preservation and processing utensils clean to limit the existence and development of B. cereus.

Doan Van Hai

References:

Nadja Jessberger , Richard Dietrich , Per Einar Granum and Erwin Märtlbauer, The Bacillus cereus Food Infection as Multifactorial Process, MDPI, 2020

Per Einar Granum, Terje Lund, Bacillus cereus and its food poisoning toxins, doi.org/10.1111/j.1574-6968.1997.tb12776.x