Staphylococcus aureus
Staphylococcal species are Gram-positive, non-motile, catalase-positive, small, spherical bacteria (cocci), which, on microscopic examination, appear in pairs, short chains, or bunched in grape-like clusters. Staphylococci are ubiquitous and impossible to eradicate from the environment. Many of the 32 species and subspecies in the genus Staphylococcus are potentially found in foods due to environmental, human, and animal contamination
Staphylococcus aureus is most commonly associated with people's respiratory passages, skin, and superficial wounds. Consequently, it is most commonly found in foods prepared by hand and not subsequently cooked, for example, salads and sandwiches. Staphylococcus aureus is destroyed by cooking, but the toxin it produces may not be destroyed. Staphylococcus aureus growth, in general, ranges from 7°C to 47.8°C, with 35°C being the optimum temperature for growth. The growth pH range has an optimum between 7.0 and 7.5.
The major cause of staphylococcal food poisoning is poor personal hygiene. Food handlers should not cough or sneeze near food, handle food while having an uncovered wound, or taste food and then put the spoon back into the pan.
Incubation period: As with most toxins the incubation period is short, usually from 1 to 7 hours.
Duration and type of illness: 6 to 24 hours. Produces toxins.
Symptoms: Predominately vomiting, also nausea and sometimes cramps and diarrhoea. The body temperature is actually lower than normal, sometimes resulting in chill like symptoms.
Control: Good personal hygiene practices. Avoid handling food directly. Cover cuts and do not handle food if you are suffering from conditions which cause you to sneeze or cough.
As the bacteria produces a toxin which is not easily destroyed by heat, it is essential that all raw food, which could contain this bacterium is always kept at a low temperature. This applies even if the food is to be cooked or heat processed.