COMPARISON OF WESTERN IMMUNOBLOTS AND GENE DETECTION ASSAYS FOR IDENTIFICATION OF POTENTIALLY ENTEROTOXIGENIC ISOLATES OF CLOSTRIDIUM-PERFRINGENS

Clostridium perfringens enterotoxin (CPE) is an important sporulation- associated virulence factor in several illnesses of humans and domesti c animals, including C. perfringens type A food poisoning. Therefore, the ability to determine the enterotoxigenicity of food or fecal C. pe rfringens isolates with simple, rapid assays should be helpful for epi demiologic investigations. In this study, Western immunoblotting (to d etect CPE production in vitro) was compared with PCR assays and digoxi genin-labeled probe assays (to detect all or part of the cpe gene) as a method far determining the enterotoxigenicity of C. perfringens isol ates. The cpe detection assays yielded reliable results with DNA purif ied from vegetative C. perfringens cultures, while Western immunoblots required in vitro sporulation of C. perfringens isolates to detect CP E production. Several cpe-positive C. perfringens isolates from diarrh eic animals did not sporulate in vitro under commonly used sporulation -inducing conditions and consequently tested CPE negative. This result indicates that cpe gene detection and serologic CPE assays do not nec essarily yield similar conclusions about the enterotoxigenicity of a C . perfringens isolate. Until further studies resolve whether these cpe -positive isolates which do not sporulate in vitro can or cannot sporu late and produce CPE in vivo, it may be preferable to use cpe detectio n assays for evaluating C. perfringens isolate enterotoxigenicity and thereby avoid potential false-negative conclusions which may occur wit h serologic assays.