Bacillus cereus

This type of bacterium is responsible for food poisoning although it has a positive effect in the form of a probiotic food additive for animals.

Bacillus cereus or B. cereus for short causes food poisoning as a result of improperly prepared and stored food. This allows these bacteria to multiply and produce ‘enterotoxins’ which are the direct cause of this illness.

The bacillus cereus bacteria

Each bacterium has a long, rod shaped appearance and is capable of causing a range of gastrointestinal illnesses which include food poisoning.

These bacteria are found in animals such as rabbits and pigs and birds such as chickens. They are found along with the salmonellaand campylobacter bacteria and can often dominate these two strains of bacteria.

There are several strains of the bacillus cereus bacteria, some of which are beneficial to animals but others are harmful to humans.

The beneficial strains are used to produce probiotic feed for animals which boosts their growth as well as reducing the number of salmonella bacteria within their digestive systems.

This also reduces the risk of salmonella food poisoning in humans.

Causes of bacillus cereus poisoning

This illness occurs via ingestion of contaminated food.

A good example of this is when food is not cooked at the correct temperature which results in it being undercooked. This situation is compounded when the undercooked food is then stored in the fridge at the wrong temperature.

This results in warm, undercooked food which is a ripe breeding ground for germs and bacteria.

These bacteria thrive in these conditions and produce spores –a series of seed like structures. These spores produce toxins (called ‘enterotoxins’) which are heat resistant and cause two types of food poisoning.

To reiterate: these bacteria cause food poisoning but this food poisoning is split into the following two versions which are:

• Diarrhoeal illness
• Emetic (vomiting) illness

Two different types of toxins cause these two forms of food poisoning.

In both cases they are caused by the consumption of infected foods due to improper cooking and storage methods. Examples of these foods include rice, chicken and red meat.

Other foods which are associated with this food poisoning include:

• Fish
• Unpasteurised milk
• Desserts
• Soups
• Salads
• Cheese and cheese based products
• Pasta
• Starches such as rice and potatoes

Symptoms of bacillus cereus

The symptoms differ according to which of the two versions of food poisoning has been contracted.

Diarrhoeal version

If you have developed the diarrhoeal version then you will experience the following symptoms:

• Upset stomach
• Abdominal pain/cramps
• Watery diarrhoea
• Nausea

These symptoms appear 6 to 15 hours after consumption and last for 24 hours or more.

Be aware that these symptoms can mimic those of clostridium perfringens food poisoning. This can make it difficult to diagnose.

Emetic version

The emetic or vomiting version includes:

• Nausea
• Stomach cramps

Diarrhoea may occur although this tends to be rare. This type of food poisoning often develops after eating undercooked rice which is later reheated –resulting in these bacteria releasing a toxin which causes these symptoms.

This type of food poisoning occurs quickly, often within a few hours. These symptoms usually last for less than 24 hours.

This too, can mimic the symptoms of other types of food poisoning, for example staphylococcus aureus.

Treatment for bacillus cereus poisoning

This is the same as for any other type of food poisoning. It involves rest and drinking plenty of fluids especially fluids which contain electrolytes.

These electrolytes help to replace salts, e.g. sodium and minerals lost as a result of vomiting and/or diarrhoea.

Serious cases of food poisoning will require hospital treatment which includes fluids being given intravenously.

Medication such as antibiotics may be prescribed as these are effective against bacterial infections. However, some strains of bacteria have developed a resistance to them which cancels out their effectiveness.

Preventing bacillus cereus poisoning

Prevention is better than cure. This means following a few, food safety precautions which include the proper cooking and storage of food products for consumption.

These include:

• Reading instructions carefully about cooking times
• Storing food in the fridge at the correct temperature
• Avoid placing raw food on top of or next to cooked food
• Using separate chopping boards, utensils etc for raw and cooked foods.
• Wash your hands before preparing, cooking and storing food. Wash them again afterwards.