Fact Sheet: Bacillus cereus
- Bacillus cereus (B. cereus) is a Gram-positive aerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed in the environment.
- B. cereus was first isolated from air in a cowshed in 1887 by Grace and Percy Frankland.
- Bacillus means ‘rod’ in Latin, and cereus means ‘wax’.
- Organisms from the B. cereus group are easily distinguished from other types of aerobic spore-forming bacteria, but are difficult to distinguish from each other. Identification can be determined based upon defining characteristics such as motility, presence of toxin crystals, haemolytic activity, and rhizoid growth.
- Vegetative cells of this bacterium can be killed with heat but its spores may survive.
- Some strains of this bacterium can be beneficial as probiotics for animals.
- B. cereus has been found to be one of the most common contaminants in pharmaceutical manufacturing facilities.
- B. cereus can grow over temperatures ranging from 5°C to 50°C with an optimum growth temperature of between 28°C to 35°C.
- B. cereus can produce toxins which cause food poisoning and can be found in milk, meat, vegetables, rice, and even prepared foods such as soups and sauces.
- The best way to prevent infection by B. cereus is to store cooked food in a wide, shallow container and refrigerate as soon as possible.
- B. cereus causes two types of illness: emetic (nausea and vomiting) and diarrhoeal
- B. cereus infections do not normally require a specific treatment, just drinking plenty of fluids to prevent dehydration and resting well, but it’s advisable to see a doctor if symptoms are persistent.
In the Lab / at Wickham Laboratories Ltd:
- Media such as B. cereus agar (BCA) can be used to examine for the presence / absence of B. cereus. Dull flat off-white / grey colonies are indicated as a positive result. This is then confirmed using identification techniques such as MALDI-ToF (Matrix Assisted Laser Desorption Ionisation-Time of Flight).
- B. cereus can be a common source of environmental contamination in the laboratory and is routinely found on environmental settle plates and inactive air monitoring.
- B. cereus contamination in manufacturing sites can often be due to the use of cardboard packaging because of its porous surface. Storage of cardboard should be limited and where possible storage materials containing laminated materials, metal foils, and blister-packs are preferable as they tend to have lower surface microbial counts. This is due to their impervious surfaces and the incorporation of high-temperature stages in their manufacture processes.
- The detection of B. cereus is commonly performed in food microbiology laboratories due to its association with food poisoning.
- B. cereus is an objectionable organism that should be considered for use in testing for products / devices intended for surgical and neonatal use.