Bacillus cereus is a rod-shaped bacterium which may cause food poisoning if ingested. It is often found in raw and processed foods which have been left out of the refrigerator for long periods of time. Cereals and rice are often responsible. It is an example of a gram positive bacteria, meaning that it has only one inner cytoplasmic membrane with a thick peptidoglycan wall.
B. cereus produces two types of illness:
- Slow onset- nausea and vomiting occur a few hours after ingestion due to a pre-formed toxin
- Rapid onset- diarrhoea and abdominal pain occur between 8 and 16 hours after ingestion due to the bacteria multiplying and producing toxin within the intestinal tract