 Staphylococcus aureus
Example 1 -- 1,364 children became ill out of a total of 5,824
who had eaten lunch served at 16 elementary schools in Texas. The
lunches were prepared in a central kitchen and transported to the
schools by truck. Epidemiological studies revealed that 95% of the
children who became ill had eaten a chicken salad. The afternoon of the
day preceding the lunch, frozen chickens were boiled for 3 hours. After
cooking, the chickens were deboned, cooled to room temperature with a
fan, ground into small pieces, placed into l2-inch-deep aluminum pans
and stored overnight in a walk-in refrigerator at 42-45°F. The following
morning, the remaining ingredients of the salad were added and the
mixture was blended with an electric mixer. The food was placed in
thermal containers and transported to the various schools at 9:30 AM to
10:30 AM, where it was kept at room temperature until served between
11:30 AM and noon. Bacteriological examination of the chicken salad
revealed the presence of large numbers of S. aureus.
Contamination of the chicken probably occurred when it was deboned. The
chicken was not cooled rapidly enough because it was stored in
l2-inch-deep layers. Growth of the staphylococcus probably occurred also
during the period when the food was kept in the warm classrooms.
Prevention of this incident would have entailed screening the
individuals who deboned the chicken for carriers of the staphylococcus,
more rapid cooling of the chicken, and adequate refrigeration of the
salad from the time of preparation to its consumption.
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