Zusammenfassung
Am 13. Juni 2007 wurde Österreichische Agentur für Gesundheit und Ernährungssicherheit von einer lokalen Gesundheitsbehörde über das gehäufte Auftreten von Bauchkrämpfen und Erbrechen am 8. Juni bei 40 Kindern zweier benachbarter Volksschulen unterrichtet. Die am 8. Juni konsumierten Schulmilchgetränke wurden als Quelle des Ausbruchs vermutet. Die Schulmilchgetränke stammten von einer lokalen Molkerei X, die am 8. Juni acht Volksschulen und zwei Kindergärten belieferte. Die kurze Inkubationszeit – alle Fälle erkrankten noch am Tag der Konsumation – und die kurze Krankheitsdauer von 1–2 Tagen ließen eine Lebensmittelvergiftung vermuten. Deskriptiv-epidemiologische und mikrobiologische Untersuchungen sowie eine retrospektive Kohortenstudie wurden zur Ermittlung des ursächlichen Agens, dessen Reservoirs und des Übertragungsmodus durchgeführt.Von 1025 Kindern der 10 Einrichtungen erfüllten 166 die Falldefinition (16,2%). Nach den Ergebnissen der Kohortenanalysen war die Konsumation von Milch, Kakaomilch oder Vanillemilch der Molkerei X mit einem 37,8 fach höherem Risiko zu erkranken, assoziiert (95% CI: 2,3–116,5). In den verbliebenen orginal-verschlossenen Milchprodukten wurden Staphylokokken-Enterotoxin A und D nachgewiesen. Sechs von 64 Viertelgemelksproben von 3 von 16 der Molkerei X zuliefernden Kühen erbrachten in der bakteriologischen Untersuchung Enterotoxin und D produzierenden Staphylococcus aureus des spa Typs t2953. Ein aus einem Nasenabstrich des Molkereibetreibers gewonnenes S. aureus Isolat war vom spa Typ t635 und wies Gene für Enterotoxin C, G, H und I auf. Die Ausbruchsuntersuchung belegte, dass die am 7. Juni in der Molkerei X hergestellten Milchprodukte die Quelle des Ausbruches einer Staphylokokken-Enterotoxikose am 8. Juni waren. Die Kühe der Molkerei X – und nicht der Molkereibetreiber – waren das wahrscheinliche Reservoir des Enterotoxin-produzierenden S. aureus-Stammes. Eine Risikoanalyse des Produktions-Prozesses ließ vermuten, dass die Toxinproduktion während Lagerung von überschüssiger pasteurisierter Milch über 3 Tage stattfand, bevor diese am 7. Juni neuerlich pasteurisiert und zu den inkriminierten Schulmilchgetränken verarbeitet wurde.
Summary
On June 13, 2007, the public health authority informed the Austrian Agency for Health and Food Safety about 40 children from two neighboring elementary schools who had fallen ill with abdominal cramps and vomiting on June 8. School milk products consumed on June 8 were suspected as the source of the outbreak. On June 8, the milk products provided by local dairy X to eight elementary schools and two nurseries. The short incubation period – all cases fell ill on the day on which the products were consumed – and the short duration of illness (1–2 days) strongly suggested intoxication. In order to identify the causative pathogen, its reservoir and the mode of transmission, a descriptive-epidemiological and microbiological investigation and a retrospective cohort study were conducted. Six of the 10 institutions served by dairy X completed questionnaires on demographics and food consumption. One school had a 79% response rate (203/258) and was chosen as the basis for our cohort study. A total of 166 of the 1025 children (16.2%) at the 10 institutions fulfilled the case definition. Consumption of milk, cacao milk or vanilla milk originating from dairy X was associated with a 37.8 times higher risk of becoming a case (95% CI: 2.3–116.5). Unopened milk products left over at the affected institutions yielded staphylococcal enterotoxins A and D. Six out of 64 quarter milk samples from three of 16 cows producing milk for dairy X tested positive for S. aureus. The isolates produced enterotoxins A and D, yielded genes encoding enterotoxins and D, and showed spa type t2953. S. aureus isolated from the nasal swab of the dairy owner harbored genes encoding enterotoxins C, G, H and I, and showed spa type t635. Our investigation revealed that the milk products produced in dairy X on June 7 were the source of the outbreak on June 8. The cows – not the dairy owner – the likely reservoir of the enterotoxin-producing S. aureus. From the risk assessment of the production process at the dairy, we hypothesize that staphylococcal toxin production took place during a 3-day period of storage of pasteurized milk prior to repasteurization for the production batch of 7.
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Schmid, D., Fretz, R., Winter, P. et al. Outbreak of staphylococcal food intoxication after consumption of pasteurized milk products, June 2007, Austria. Wien Klin Wochenschr 121, 125–131 (2009). https://doi.org/10.1007/s00508-008-1132-0
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DOI: https://doi.org/10.1007/s00508-008-1132-0