Outbreak of acute gastroenteritis in an Austrian boarding school, September 2006

An outbreak of acute gastroenteritis occurred in September 2006 in a boarding school in eastern Austria. Of 113 cases, 101 were hospitalised. In order to identify the outbreak source, a retrospective cohort study on the group at risk was performed, including 222 pupils and 30 staff members. Food exposure in the canteen of the school was identified as the most relevant common link among the cases in the case series investigation. Although the preliminary microbiological investigation made Norovirus infections possible, an in-depth descriptive epidemiological investigation later pointed to food intoxication rather than a viral infection as the cause of the outbreak. The analytical epidemiological investigation implicated boiled rice and chicken wings served in the canteen as the most likely source of the outbreak. Staphylococcus aureus was identified as the causative agent. Further molecular characterisation revealed that the predominant S. aureus type in this outbreak was a new spa type, t2046. The same spa type was isolated from stool specimens of the majority of the cases investigated, from samples of the incriminated boiled rice, and also from a swab of a palmar skin lesion of one of the healthy kitchen workers, who is therefore the most likely source of contamination. This outbreak underlines again the importance of compliance with the basic guidelines for kitchen hygiene.