Food poisoning

We've all driven the porcelain bus at some time. How can you avoid food poisoning?
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  • Updated:1 Jun 2005

06.Food poisoning bugs 101

Bluff bacteria with the boffins - here's what you need to know:

We've used the term "bacteria" here to refer to the micro-organisms that grow on food and can infect anyone who eats it. Strictly speaking, these harmful bacteria are known as "pathogens". Many other bacteria are harmless.

The symptoms of "food poisoning" are sometimes caused by toxins produced by bacteria and other times caused by bacteria themselves infecting the body. The commonest symptoms are vomiting and diarrhoea, usually preceded by abdominal cramps and sometimes a headache.

Usually it takes large numbers of food poisoning bacteria to cause illness, as our body’s natural defences can usually take care of most smallish invasions, but infants babies and people with weakened defences (such as those who are already sick, and elderly and those on immunosuppressive drugs) are much more susceptible, so preparing food for them demands extra care and we should always be aware of the extra precautions needed for these people.

In Australia, the bugs that commonly cause problems are:

  • Salmonella Just one drop of contaminated chicken juice can make you very sick. It usually strikes within 12-24 hours after of eating contaminated food. You’re likely to feel really awful for a couple of days, and may not fully recover for weeks.
  • Clostridium perfringens Likely sources in the home are meat, poultry dishes, casseroles and the like that are cooled slowly and inadequately refrigerated. It can cause intense abdominal cramps and diarrhoea that begin 8-22 hours after eating the contaminated food. The illness is usually over within 24 hours.
  • Vibrio parahaemolyticus It’s often caught from sea-food produced in warm coastal waters. Oysters and other sea-food eaten raw are a likely source. The illness is usually mild or moderate and lasts about two to three days.
  • Staphylococcus aureus from the human body can grow and produce its toxin in foods like home-made pasta and fermented sausage — typically foods that get a lot of handling during preparation. Wash your hands!
  • Campylobacter is usually caught by eating contaminated poultry that’s not adequately cooked. It’s mostly spread by cross-contamination, and It can strike up to 10 days after you’ve eaten the contaminated food, with similar symptoms to salmonella. The effects will last for several miserable days.
  • Bacillus cereus can be a problem in cereal-based products, mashed potato, vegetables, minced meat, liver sausage and soups, and it’s often associated with fried or boiled rice. There are two forms of poisoning — caused by two different toxins. A fairly mild form develops within 6-15 hours and usually lasts for about 24 hours. A more severe form starts within 4 - 6 hours of infection and generally lasts for less than 24 hours. It produces nausea and vomiting and; occasionally, abdominal cramps and/or diarrhoea as well. It’s often associated with fried or boiled rice.
  • Escherichia coli (E. coli) don’t often cause illness, but the bugs are very common. They are always exist found in the guts of animals, including humans. Most E. coli are harmless and normally serve a useful function in the body by suppressing the growth of harmful bacteria and by producing appreciable amounts of vitamins. But the presence of E. coli in food is an indication of faecal contamination and the possibility of the presence of far worse bacteria that could cause serious illness. Unfortunately not all E. coli are harmless. The strain E. coli O157 is particularly dangerous for two reasons. Doses of just a few cells (possibly as few as 10) can result in illness, and the toxin it produces is extremely potent, causing anything from mild diarrhoea to serious urinary and gastrointestinal complications, including internal bleeding. As with other strains of E. coli, E. coli O157 is normally found in cows’ and other animals’ guts and gets into meat in the abattoir. It’s a relatively new type of infection, first recognized in Canada in 1985.

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