A simple method for the isolation and determination of Clostridium perfringens

Summary A method for the isolation and determination of small numbers of vegetative cells or spores of Clostridium perfringen has been developed based on enrichment under anaerobic conditions in a fluid thioglycollate medium without dextrose, containing 400 g of D-cycloserine/ml at 46°C for 18 h (PEM). It allows virtually complete recovery of vegetative cells of all strains of Clostridium perfringens tested, whereas facultative anaerobes present in food are inhibited. Undamaged Clostridium perfringens spores can also be detected by this procedure. After enrichment, isolation of Clostriduum perfringens is carried out on iron sulphite agar at 46°C for 18 h. Typical black colonies are picked and confirmed by the following tests: neutralization of the -toxin by a specific diagnostic antiserum and absence of indole, motility, and ability to liquify gelatin.