Salmonella Thompson associated with improper handling of roast beef at a restaurant in Sioux Falls, South Dakota.

In October 1996, we investigated an outbreak of Salmonella serotype Thompson infections associated with Restaurant A in Sioux Falls, South Dakota, and conducted two cohort studies among persons who ate at luncheons catered by Restaurant A. Fifty-two Salmonella Thompson infections were identified between 29 September and 14 October 1996. Infections occurred among employees and patrons at Restaurant A and among attendees at three luncheons catered by the restaurant on 7 October. Roast beef cooked at Restaurant A was the only food item significantly associated with illness. Cooking times and storage temperatures for roast beef were inadequate to prevent multiplication of Salmonella, and the chefs were unaware of proper cooking and storage temperatures. We conclude that improper handling of roast beef probably caused this outbreak of Salmonella Thompson infections. Better knowledge of food safety practices by the cooking staff at Restaurant A, through required food safety education, might have prevented the outbreak.