Large-Scale Staphylococcus aureus Foodborne Disease Poisoning Outbreak among Primary School Children

A large-scale food poisoning outbreak happened at a school canteen in Ninh Binh Province, Vietnam, in 2018, resulting in the hospitalization of 352 students with clinical symptoms indicative of a staphylococcal food poisoning. A subsequent laboratory investigation detected Staphylococcus aureus in two food items—deep-fried shrimp and chicken floss—at up to 103 CFU/mL, and staphylococcal enterotoxins (SEs) in chicken floss at ≥0.211 ng SEs/g. S. aureus was also isolated from patients’ vomit and stool samples, and kitchen workers’ stool samples, as well as in frozen chicken meat, but not on the kitchen workers’ hand surfaces, suggesting the cause of this food poisoning outbreak was S. aureus contamination of the chicken meat. Molecular characterization revealed the S. aureus strains isolated from all samples were closely related; all belonged to sequence type (ST) ST6 and spa type t701 and carried both sea and sec genes. This SE-producing strain was resistant to penicillin and tetracycline, while still susceptible to oxacillin, erythromycin, gentamicin, methicillin, and vancomycin. Since S. aureus food poisonings are often underreported, our investigation added to the sparse qualitative and quantitative data of pathogenic S. aureus monitoring and surveillance in Vietnam, providing needed knowledge to guide preventative measures for future outbreaks.