Why is Staphylococcus aureus often described as an international picnic pest?

S. aureus is a member of at least 20-30% of people's normal flora, so it is easily transmitted to foods, where it is capable of growth on several different foods. The pathogen grows very well at room temperature or slightly warm outdoor temperatures. Staphylococcal food poisoning is not caused by the bacterium but by the enterotoxin it produces during growth, which means the food could have been heated, and the heat-tolerant enterotoxins could have survived. Mayonnaise-based salads as well as custard- and cream-filled desserts are among the most common foods associated with staphylococcal food poisoning.