Staphylococcus aureus is an important aetiological agent of food intoxications in the
European Union as it can cause gastro-enteritis through the production of various staphylococcal
enterotoxins (SEs) in foods. Reported enterotoxin dose levels causing food-borne illness are scarce
and varying. Three food poisoning outbreaks due to enterotoxin-producing S. aureus strains which
occurred in 2013 in Belgium are described. The outbreaks occurred in an elderly home, at a barbecue
event and in a kindergarten and involved 28, 18, and six cases, respectively. Various food leftovers
contained coagulase positive staphylococci (CPS). Low levels of staphylococcal enterotoxins ranging
between 0.015 ng/g and 0.019 ng/g for enterotoxin A (SEA), and corresponding to 0.132 ng/g for
SEC were quantified in the food leftovers for two of the reported outbreaks. Molecular typing of
human and food isolates using pulsed-field gel electrophoresis (PFGE) and enterotoxin gene typing,
confirmed the link between patients and the suspected foodstuffs. This also demonstrated the high
diversity of CPS isolates both in the cases and in healthy persons carrying enterotoxin genes encoding
emetic SEs for which no detection methods currently exist. For one outbreak, the investigation
pointed out to the food handler who transmitted the outbreak strain to the food. Tools to improve
staphylococcal food poisoning (SFP) investigations are presented.