Quantitation of Clostridium perfringens in foods.

A procedure is described for identifying and enumerating Clostridium perfringens in foods by means of a simplified agar plating method, followed by confirmation of black colonies in tubes of motility-nitrate medium and sporulation broth. The test is routinely completed within 48 hr. Under experimental conditions, the procedure has been used to quantitatively recover various levels of C. perfringens contamination in a variety of foods and has recovered as few as ten C. perfringens per g without interference from food constituents and associated flora. Under practical conditions of field application, the method has been used to investigate five food-poisoning outbreaks, and C. perfringens was implicated as the etiological agent in two of these outbreaks.