Staphylococcal Food Poisoning

Staphylococcal food poisoning occurs following the ingestion of enterotoxins produced by enterotoxigenic staphylococci when they reach levels of approximately 10⁶ CFU/g or higher in food. Staphylococcus aureus is the most important enterotoxigenic species, although Staphylococcus intermedius, Staphylococcus hyicus, and Staphylococcus epidermidis are also capable of producing enterotoxins.

Factors Affecting the Growth of Staphylococcus aureus

Temperature: The optimum growth temperature is 37°C, with a growth range of 6.7–47.8°C. The optimum temperature for enterotoxin production is 40–45°C, while toxin production may occur between 10–48°C. Growth and toxin production decrease or cease outside these ranges.

pH: The optimum pH for growth is 6–7, with a growth range of pH 4–10. Enterotoxin production generally occurs between pH 5.5 and 6.6 and is inhibited at pH values below 5 or above 9.

Water Activity (aw), Salt Concentration, Nutrients, and Minerals: Unlike many other bacteria, S. aureus is osmotolerant and can grow in environments containing up to 3.5 M NaCl and at water activity values below 0.86. It is also highly resistant to dry environmental conditions. The minimum water activity and salt concentrations required for growth and toxin production are approximately 0.83 aw / 20% salt and 0.86 aw / 10% salt, respectively.

Atmospheric Conditions: Studies have shown that S. aureus grows 9–17 times more rapidly under aerobic conditions than under anaerobic conditions, with enterotoxin production increasing accordingly. Although growth is slower under anaerobic conditions, enterotoxin production can still be detected after approximately 120 minutes of incubation.

Foods Commonly Associated with Staphylococcal Enterotoxins

Staphylococcal enterotoxins (SE) are primarily associated with foods of animal origin, including cooked or undercooked beef, pork, turkey, and poultry, milk powder, cheese and other dairy products, meat and potato salads, fish, eggs, cream-filled pastries, and frozen desserts or sauces prepared with milk, sugar, and eggs.

Symptoms of Staphylococcal Food Poisoning

Symptoms typically develop 30 minutes to 8 hours after consumption, most commonly within 2–4 hours. Clinical signs include nausea, vomiting, severe abdominal cramps, abdominal pain, and diarrhea. Less common symptoms include headache, dizziness, general weakness, weak pulse, shallow respiration, shock, and enteritis.