A Clostridium perfringens outbreak traced to temperature-abused beef stew, Norway, 2012

On 21 January 2012, the Norwegian Food Safety Authority was informed about gastrointestinal illness among 111 swimming club members, who were staying at a hotel in Trondheim. A hotel dinner on 20 January was their only common meal. Kitchen staff were interviewed, and food leftovers and kitchen environment were sampled. A case was defined as a swimming team member staying at the hotel from 20 to 22 January, who fell ill with diarrhoea, abdominal pain or nausea during this period. A total of 43 cases were identified, with median duration of symptoms of 35 hours. cpe-positive Clostridium perfringens (3.8 x 10⁸ CFU), but not Bacillus cereus, was isolated from beef stew eaten by cases. cpe-negative C. perfringens was detected in a sample from the kitchen floor. SDS-PAGE showed indistinguishable protein profiles among C. perfringens cultures isolated from the beef stew, but slightly different profiles from the culture isolated from the kitchen floor. Cohort analysis showed that eating beef stew and rice was significantly associated with illness. No pathogens were detected in the rice. The temperature control of the stew, but not of the rice, was poor. Our results strongly indicate that cases were infected by Clostridium perfringens in beef stew that had inadequate temperature control during preparation.