Prevalence and characterization of enterotoxin gene-carrying Clostridium perfringens isolates from retail meat products in Japan.

Clostridium perfringens is an important anaerobic pathogen causing food-borne gastrointestinal (GI) diseases in humans and animals. It is thought that C. perfringens food poisoning isolates typically carry the enterotoxin gene (cpe) on their chromosome, while isolates from other GI diseases, such as antibiotic-associated diarrhea, carry cpe on a transferable plasmid. However, food-borne GI disease outbreaks associated with C. perfringens isolates carrying plasmid-borne cpe (plasmid cpe isolates) were recently reported in Japan and Europe. To investigate whether retail food can be a reservoir for food poisoning generally, we evaluated Japanese retail meat products for the presence of two genotypes of enterotoxigenic C. perfringens. Our results demonstrated that approximately 70% of the Japanese retail raw meat samples tested were contaminated with low numbers of C. perfringens bacteria and 4% were contaminated with cpe-positive C. perfringens. Most of the cpe-positive C. perfringens isolates obtained from Japanese retail meat carried cpe on a plasmid. The plasmid cpe isolates exhibited lower spore heat resistance than did chromosomal cpe isolates. Collectively, these plasmid cpe isolates might be causative agents of food poisoning when foods are contaminated with these isolates from equipment and/or the environment after cooking, or they may survive in food that has not been cooked at a high enough temperature.