Four Foodborne Disease Outbreaks Caused by a New Type of Enterotoxin-Producing Clostridium perfringens

Abstract

The epidemiological and bacteriological investigations on four foodborne outbreaks caused by a new type of enterotoxin-producingClostridium perfringensare described.C. perfringensisolated from patients of these outbreaks did not produce any known enterotoxin and did not carry theC. perfringensenterotoxin gene. However, the culture filtrates of these isolates induced the accumulation of fluid in rabbit ileal loop tests. The molecular weight of the new enterotoxin may be between 50,000 and 100,000, although the knownC. perfringensenterotoxin is ca. 35,000. This new enterotoxin was heat labile, and its biological activities were inactivated by heating for 5 min at 60°C. The new enterotoxin was sensitive to pH values higher than 11.0 and protease treatment but was resistant to trypsin treatment. These results suggest that the new enterotoxin may be a protein. AlthoughC. perfringensenterotoxin induced morphological changes in Vero cells, the changes induced by the new enterotoxin differed from those by the knownC. perfringensenterotoxin. The new enterotoxin also induced morphological changes in L929 cells, whereas the knownC. perfringensenterotoxin did not, because L929 cells lacked an appropriate enterotoxin receptor. AlthoughC. perfringensenterotoxin is recognized as the only diarrheagenic toxin responsible forC. perfringensfoodborne outbreaks, the results of the present study indicate thatC. perfringensisolated from these four outbreaks produced a new type of enterotoxin.