Bacillus cereus

Bacillus cereus

Bacillus cereus is a Gram-positive, facultatively anaerobic, endospore forming, large rod-shaped bacterium.

Bacillus cereus is found in dust, soil and spices. It can survive normal cooking as a heat-resistant spore, and then revert to a bacterial form. If the subsequent storage temperature is incorrect, bacteria can begin to multiply once more. Note that bacterial growth is not altogether halted by holding food below 5°C or above 63°C.

The major sources of Bacillus cereus poisoning are cereals and cooked rice. If rice is cooked for later consumption, it should be chilled quickly and properly stored.

Incubation period: From 0 to 24 hours.

Duration and type of illness: Usually less than 24 hours. Produces toxin.

Symptoms: Two different types of toxins are produced by this organism. One, which is easily destroyed by heat and one which is not destroyed by heat. The main symptom of the former is predominantly diarrhoea, while the latter usually causes vomiting.

Control: Good hygiene practices. Ensure that starchy products such as rice are chilled and not held in the danger zone, i.e., between 5°C and 63°C.