Outbreak of staphylococcal food intoxication after consumption of pasteurized milk products, June 2007, Austria.

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.

An outbreak of febrile gastroenteritis associated with jellied pork contaminated with Listeria monocytogenes.

In September 2008, the Austrian Agency for Health and Food Safety (AGES) learned of an outbreak of diarrheal illness that included a 71-year-old patient hospitalized for gastroenteritis with a blood culture positive for Listeria monocytogenes. Three stool specimens provided by seven of 19 persons attending a day trip to a foreign city, including a final break at an Austrian tavern, yielded L. monocytogenes. All isolates were of serovar 4b and had fingerprints indistinguishable from each other. A cohort study revealed that the outbreak of gastroenteritis occurred among 16 persons who had eaten dinner at the wine tavern on September 6. Of the 15 persons who ate from platters of mixed cold-cuts, 12 (80%) developed symptoms of febrile gastroenteritis within 24-48 h. The median age of those who became ill was 62 years. A 72-year-old patient recovered from gastroenteritis but was hospitalized with bacterial meningitis on day 19 after the dinner. The epidemiological investigation identified the consumption of mixed cold-cuts (including jellied pork) at the wine tavern as the most likely vehicle of the foodborne outbreak (P = 0.0015). This hypothesis was confirmed by microbiological investigation of jellied pork produced by the tavern owner on September 3. L. monocytogenes was isolated from leftover food in numbers of 3 x 10(3)-3 x 10(4) colony forming units/g and was indistinguishable from the clinical outbreak isolates. Symptoms reported by the 12 patients included unspecified fever (12x), diarrhea (9x), headache (5x), vomiting (4x), body aches (2x) and sore throat (1x). Active case finding identified one case of rhombencephalitis (female, age 48) among another group of four guests, among whom only the patient and her asymptomatic husband had eaten jellied pork on September 6. This is the first outbreak of L. monocytogenes-associated gastroenteritis reported in Austria. The occurrence of a secondary case of meningitis (diagnosed on day 19 after consumption of jellied pork) indicates a significant risk of systemic listeriosis among elderly patients with febrile gastroenteritis caused by L. monocytogenes; antibiotic therapy should therefore be considered in such cases of documented listerial gastroenteritis.