Isolation and identification of cpe-positive Clostridium perfringens in bulk and packed dehydrated vegetables

The enterotoxin (cpe) gene in C. perfringensis is responsible for food poisoning and gastroenteritis. The dried vegetables are suitable environment for spore forming bacteria such C.perfringensis, because of spore resistance against harsh environments such as temperature, dehydrate etc. The aim of this study was to isolate and identify cpe-positive C. perfringens in dried vegetable.

In a descriptive study, 140 samples including 70 bulk and 70 packed dried vegetables collected from various part of Tehran were tested. At first samples were inoculated in thioglycolate as enrichment medium, and then cultured into sulfite polymyxin sulfadiazine (SPS).
The colonies were identified by phenotypic and biochemical tests and Duplex PCR was carried out for detection of alpha toxin (cpa) and enterotoxin (cpe) genes.

Out of 140 tested samples 13 samples (9.3%) were identified as C. perfringens in which all of them were positive for cpa but negative for cpe gene. The rate of contamination of packed vegetables was 12.8% whereas 5.7% for bulk.

The result of this study showed that C. perfringens contaminations in dried packed vegetables is possible, and that might happen during drying and packaging possess.