Enterotoxin production by Staphylococcus aureus: An outbreak at a Barcelona sports club in July 2011

An outbreak of acute gastroenteritis due to staphylococcal food poisoning occurred in July 2011 at a summer school held by a sports club in Barcelona (Catalonia, Spain). Of the 42 cases involved, 20 were hospitalised. To identify the outbreak source, a retrospective cohort study was performed on the group at risk, which included 73 summer school students and 18 staff members. Food exposure at the sports club restaurant was identified as the most relevant common link among the study cohort. Although the preliminary microbiological investigation suggested that enterotoxigenic Staphylococcus aureus (S. aureus) infections were the possible source, enterotoxin types A and D were identified, quantified and confirmed in the different biological samples collected. A descriptive, in-depth epidemiological and clinical investigation subsequently pointed to food intoxication rather than bacterial infection as being the cause of the outbreak. Molecular investigation of the strain isolates, using pulsed-field gel electrophoresis typing, revealed that all eight strains of S. aureus had the same profile and spa type (t008). Samples of the incriminated foods, i.e., boiled macaroni, tuna and fresh tomatoes, specimens of vomit of those affected, and bilateral fingernail scrapings and nasal swabs of food handlers were shown to be the common source of transmission of the contamination. Following the outbreak, appropriate hygiene and control measures could be implemented to prevent any recurrence.