Bacillus cereus and other Bacillus species

This pathogen can cause two types of foodborne illness—the diarrhoeal type and the emetic or vomiting type. Like Clostridium perfringens the illness is a mild one, but unpleasant nevertheless.


The diarrhoeal type occurs within 8 to 16 hours of eating the food and lasts for about 24 hours. Foods involved vary from starchy vegetables, meat products, cereal foods, sauces, puddings and spices. A much shorter time is required for symptoms of the vomiting type to appear (30 minutes to five hours). The most common food associated with the vomiting type is rice. Cooked rice should always be cooled and stored in the refrigerator.

Bacillus cereus can form heat resistant spores and a heat resistant toxin. If cooked food is allowed to cool slowly the spores can germinate. If growth occurs then the toxin can form under certain conditions. Reheating or lightly cooking the food will not destroy this toxin.

Although this bacteria can grow and produce toxin at refrigeration temperatures, it does so much more slowly than at room temperature. Precooked food should not be stored in the refrigerator for more than two to three days.

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