This bacterium is part of the normal flora of humans and is found on nasal passages, skin and mucous membranes and, especially important for food handlers, in infected wounds. Some strains of Staphyloccous aureus are capable of producing a highly heat-stable protein toxin when conditions of temperature, acidity, moisture and nutrition are right. This enterotoxin can cause food-borne illness in humans when it is consumed.
The most common symptoms of staphylococcal intoxication are nausea, vomiting, retching, abdominal cramping and prostration. The onset of symptoms is usually rapid, and, in many cases, acute, depending on individual susceptibility to the toxin, the amount of contaminated food eaten, the amount of toxin in the food ingested and the general health of the victim. Recovery generally takes two to three days.
Foods that are frequently incriminated in staphylococcal food-borne illnesses include meat and meat products; poultry and egg products; salads such as egg, tuna, chicken, potato and macaroni salad; bakery products such as cream-filled pastries, cream pies and chocolate éclairs; sandwich fillings; and milk and dairy products. Foods that require considerable handling during preparation and that are kept at slightly elevated temperatures after preparation are frequently involved in staphylococcal food-borne illness.
Since humans are natural reservoirs of S. aureus in their noses, throats, hair and skin, food handlers are often the source of contamination in food-borne illness outbreaks. However, equipment and environmental surfaces can be sources of cross contamination. Enterotoxin is produced in foods that have not been kept hot enough (135 degrees F, or above) or cold enough (41 degrees F, or below). So, proper holding, cooling and reheating of foods is required. Foods that have frequently been implemented in outbreaks involving S. aureus include those that require processing by human hands, so careful and frequent hand washing is essential for food handlers. Proper procedures for cleaning, treatment and bandaging of wounds as well as coverage by food-grade gloves must be followed.