Staphylococcal food poisoning is a gastrointestinal illness caused by an enterotoxin made by the Staphylocococcus aureus bacteria.
Staphylococcus aureus is commonly found on human skin of healthy people and can be spread to food if hands are not properly washed prior to food handling. The bacteria produce enterotoxin, which causes the gastrointestinal illness S. aureus is also associated with other health problems ranging from skin infections to severe invasive infections of the lungs or the heart. Drug resistant strains are common, especially in hospital settings. This summary refers only to staphylococcal food poisoning.
Staphylococcal food poisoning is among the most common causes of gastroenteritis worldwide. The presence of staphylococcal enterotoxin in food is usually due to contamination from a food handler that is carrying S.aureus or cross contamination of ready to eat food with raw food. To prevent food becoming contaminated, good food safety practices should be followed, such as frequent hand washing, wearing gloves when handling foods, and separating areas where raw and cooked products are handled.
Symptoms include:
- vomiting
- nausea
- diarrhea, usually watery but sometimes with blood
- cramps
- other symptoms may include mild fever, weakness, dizziness and chills.
Symptoms usually start one to 10 hours after exposure and go away in one to two days. In some cases, the illness may be more severe. If you have serious symptoms, you should see your healthcare provider or call 811 for advice.
Staphylococcal food poisoning can happen when two things occur:
- The S. aureus bacteria is in the food; and
- The food is kept at incorrect temperatures for too long, which allows the pathogen to grow and make the enterotoxin.
It is the enterotoxin that causes illness.
Although S. aureus can be found in food-producing animals and raw foods, humans are considered the main reservoir for this pathogen. Many healthy people have S.aureus on their skin and mucous membranes, for example inside the nose. Food can become contaminated during preparation if the food handler is a carrier of S.aureus and touches food with contaminated skin or by coughing and sneezing.
S. aureus can grow and produce enterotoxin in food only under certain conditions. For example, it needs temperatures of between 7°C and 48°C to be able to grow, with an optimum temperature of 37°C. Once large amounts of bacteria grow, they can produce enterotoxin (greater than 10,000 S. aureus per gram of food).
Foods most often linked to staphylococcal food poisoning are poultry and cooked meat products such as ham or corned beef. Other foods implicated are milk and milk products, canned food and bakery products.
Staphylococcal food poisoning is usually self-limiting, resolving within one or two days. In a small percentage of cases, it can be more severe, especially in infants, the elderly and immunocompromised patients.
The diagnosis is usually made based on symptoms. Staphylococcal food poisoning can be confirmed if the enterotoxin or large numbers of S. aureus are found in the food. S. aureus can also be detected in stool samples from patients.
Most people recover without treatment. If diarrhea or vomiting is severe, your healthcare provider may give you fluids to prevent dehydration. Antibiotics are not helpful because the symptoms are caused by the enterotoxin and not the bacteria.
To avoid contaminating food with S. aureus, handle and prepare food safely:
- Food handlers should thoroughly wash hands and use appropriate protective equipment (e.g., gloves).
- Food handlers should properly cover skin cuts or wounds before handling food. If this is not possible, they should not work while handling food until the lesions have healed.
- Keep work surfaces clean and separate areas where raw and cooked foods are handled.
To prevent growth of S. aureus and the formation of enterotoxin:
- Keep food at a temperature above 60°C or refrigerated below 4°C.
-
Cool cooked foods that will not be immediately consumed to below 4°C within 6 hours.
- When reheating food, ensure that the temperature reaches at least 74°C.
Control measures should be applied first to avoid contaminating the food with
S. aureus and also to prevent growth and the formation of enterotoxin in the food.
- Ensure raw foods of animal origin are obtained following good hygienic practices, to reduce the possibility of
S. aureus contamination.
- Food handlers should use appropriate protective clothing (e.g. gloves) and thoroughly wash hands.
- Food handlers with skin lesions should have them properly covered prior to handling food. If this is not possible, they should not work while handling food until the lesions have healed.
- Avoid cross-contamination by keeping work surfaces clean and ensuring separation between areas where raw and cooked foods are manipulated.
- Ensure food is maintained either at a temperature above 60°C or refrigerated below 4°C.
-
Cool cooked foods that will not be immediately consumed to below 4°C within 6 hours.
- When reheating food, ensure that the temperature reaches at least 74°C.
