They thrive in Singapore's warm and moist environment and often cause food poisoning. CHARMAINE KHOO finds out how to avoid food contamination

Bacillus cereus, campylobacter jejuni, staphylococcus aureus, vibrio parahaemolyticus and salmonella.

Do these sound like the names of famous centurions leading an invading Roman legion?

If you thought so, you would be right in one aspect. These are the names of bacteria that can invade your body when you eat contaminated food.

Food poisoning is often caused by contaminated food.

Associate Professor Raymond Lin, the head and senior consultant at the division of microbiology at the National University Hospital, said these bacteria grow rapidly under certain conditions.

"They thrive in temperatures from 25 to 37 deg C and grow in moist or wet environments which contain an ample
supply of proteins and other nutrients," he said.

"So most food kept at room temperature or warmer provides the environment for such growth."

Associate Professor Helen Oh, a senior consultant in infectious disease at Changi General Hospital, said non-typhoidal salmonella and staphylococcus aureus are among the common bacteria responsible for food poisoning in Singapore.

Food poisoning can affect anyone although certain groups are at greater risk.

Said Prof Oh: "Pregnant women, young children and the elderly are more vulnerable because they have lower immunity."

Depending on the type of bacteria, the ingesting of contaminated food can give rise to symptoms which range from mild to severe.

Diarrhoea, vomiting and fever are the typical symptoms, said Prof Lin.

He added: "Severe loss of fluid in the very young elderly or those that are undernourished can lead to organ failure and even death."

Prof Lin said that in most cases antibiotics have no effect and supportive treatment is enough. This means providing sufficient fluid and nutrition to replace that which was lost through diarrhoea and
vomiting.

In some circumstances - when very young children especially those below three months old, get infected, in people with severe symptoms, and in those where the bacteria have entered the bloodstream - hospitalisation and antibiotic treatment may be necessary.

Here are some of the foods you should be careful with:

Rice products and meats: Bacillus cereus is often associated with these.
"When steamed rice is left out for six hours, it allows the initial small and harmless contamination of bacillus cereus to grow to large numbers. This produces a heat stable toxin," said Prof Lin.

Frying the rice does not remove the toxins and this can cause vomiting, he explained.

Raw chicken and raw (non-pasteurised) milk: These should be thoroughly cooked by boiling roasting or frying so that any campylobacter jejuni is killed.

Poultry and daily products: Salmonella can be found in these. As in th case of campylobacter jejuni, this bacteria can be eliminated through boiling, roasting or frying.

Salads and bakery goods like cream pies: Staphylococcus aureus can infect these foods.

Staphylococcu aureus is often transferred to food from the hands of people, particularly those with staphylococcal infections of their skin, said Prof Lin.

Raw seafood: Vibrio parahaemolyticus food poisoning can occur when eating raw or inadequately cooked seafood.

Be sure that raw seafood in particular, is absolutely fresh when consuming it.

AVOID INFECTION

Proper storage of food in the fridge is a good way to avoid cross-contamination and ensure that food is safe to eat.

Associate Professor Helen Oh, a senior consultant in infectious disease at Changi General Hospital, said that food stored in the fridge must be covered with lids, aluminium foil or plastic wrap and not kept in open containers.