COMPARISON OF A NEW, BISMUTH-IRON-SULFITE-CYCLOSERINE AGAR FOR ISOLATION OF CLOSTRIDIUM-PERFRINGENS WITH THE TRYPTOSE-SULFITE-CYCLOSERINE AND BLOOD AGARS

A new differential and selective, bismuth-iron-sulfite-cycloserine (BI SC) medium, for isolation and enumeration of Clostridium perfringens f rom food and feces, was developed. The medium was compared with the wi dely-used tryptose-sulfite-cycloserine (TSC) medium and blood agar (BA ) in recovering actively growing cells, cold- (refrigerated and frozen ) stressed, and heat-stressed C. perfringens cells, and heat-activated spores from human feces. Both selective media were satisfactory in re covering actively growing cells and heat-activated spores of C. perfri ngens. Both were inferior to non-inhibitory blood agar in recovering h eat or cold-stressed cells. The advantages of the new BISC medium over the TSC medium were: elimination of the need to prepare pour- or over lay-agar plates, which simplified inoculation of specimens on the medi um and simplified the subcultures of colonies for confirmatory identif ication. All colonies of C. perfringens developed on BISC were black o r dark gray. This was contrary to TSC medium, which gave, on average, 39.6% of white colonies when inoculated with the pure cultures of C. p erfringens.