Bacillus cereus is a spore-forming, motile, aerobic, rod-shaped and gram-positive bacteria that can also grow well in anaerobic conditions. The bacteria is a common soil saprophyte and can easily spread to different types of food especially plant-based. It is also frequently found in meat, egg and dairy products. There are also psychrotrophic strains which have become an increasing problem for the dairy industry.
B.cereus produces 2 types of toxins, the first being an emetic toxin and the second being an enterotoxin. The bacteria causes two types of food poisoning, the first being the diarrhoeal type and the second being an emetic type. The diarrhoeal type (infection) is caused by the enterotoxins which are produced during vegetative growth of the bacteria in the small intestine. The emetic type (intoxication) is caused by toxins produced by the growing cells in the food. In both cases, the causing factor of the food poisoning comes from the spores the bacteria produce which may survive after food has been heat-treated. This heat treatment will cause the spores to germinate and start producing either of the toxins depending on where the spore is found in the food.