Clostridium perfringens food poisoning: use of serotyping in an outbreak setting.

An outbreak of Clostridium perfringens food poisoning occurred among attendees of a firehouse luncheon. The predominant symptoms of diarrhea (100%) and abdominal pain (81%) among case-patients, the mean incubation period (13.4 h), and the mean duration of illness (21.2 h) were all characteristic of C. perfringens enteritis. Roast beef, although not epidemiologically implicated, was the most likely vehicle of transmission. Fecal specimens from case-patients contained a median C. perfringens spore count of greater than 10(6) and yielded isolates that were heat sensitive and predominantly nonhemolytic, produced C. perfringens enterotoxin A, and, in the majority of specimens (four of five), were identical in serotype. Food samples were negative. This outbreak demonstrates that following enumeration of C. perfringens from a suitable number of fecal specimens from case-patients, serotyping of the isolates may be helpful in implicating C. perfringens as the cause of foodborne illness. This is especially true when implicated food items test negative or are no longer available for testing.