Quantitation of Clostridium perfringens in Foods

Abstract

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. Clostridium perfjringens is recognized as the principal cause of gas gangrene in man and as the specific causal agent of lamb dysentery; lamb, sheep, and newborn calf enterotoxemia; "struck" in sheep; and an acute and fatal disease of very young piglets. However, outside of Great Britain, relatively little attention has been given to the possibility that this organism is also capable of causing gastroenteritis in man. C. perfringens is one of the principal causes of foodborne illness in the British Isles, and practically all of the outbreaks described in the literature involve meat dishes. Usually the meat was cooked the day before serving and allowed to cool slowly, either in its own juices or separately. Apparently, the two factors of precooking and lack of immediate refrigeration allow the development of the extremely large numbers of C. perfringens associated with this type of food poisoning. English studies (Knox and 1\IacDonald, 1943; Duncan, 1944; Hobbs et al.; 19.53; Dische and Elek, 1957) reveal C. perfringens food poisoning is caused by atypical type A strains of the organisms. They produce heat-resistant spores, produce relatively small amounts of the a-toxin, and rarely produce any 0-toxin. In the outbreaks reported by McClung (1945) and by Hart, Sherwood, and Wilson (1960) in the United States, the clinical picture resembled that of the English outbreaks, and strains of C. perfringens, type A, were isolated. At the present time, only a few laboratories examine foods incriminated in foodborne disease outbreaks for C. perfringens because of the lack of quantitative methods and the difficulties associated with anaerobic cultivation. To facilitate examination of foods for C. perfringens, investigations have been in progress in this laboratory on the simplification of methods for identification and enumeration of this organism. A procedure has been developed and is presented below. MATERIALS AND MIETHODS Cultures. Included in this study were members of each of the six recognized types of C. perfringens (A through F) obtained from both the American Type Culture Collection and National Collection of Type Cultures (Great Britain). Also included were those strains most frequently encountered in food-poisoning outbreaks in England and designated as Hobbs' strain...

Satellite Food‐service System Assessment in Terms of Time and Temperature Conditions and Microbiological and Sensory Quality of Spaghetti and Chili

“…In addition, coliform counts were obtained using Violet Red Bile Agar with an agar overlay and clostridial counts using Sulfite-Polymyxin-Sulfadiazine Agar with an agar overlay. Isolation and quantitation of staphylococci and clostridia were performed by the methods of Baird-Parker (1962) and Angelotti et al (1962) respectively. Procedures for incubation and enumeration of all plates were the same as those given in the Bacteriological Analytical Manual (Olson, 1969), and Recommended Methods for the Microbiological Evaluation of Foods (APHA, 1966).…”

EFFECT OF NITROGEN SOURCE ON GROWTH AND EXOPROTEASE PRODUCTION BY Clostridium perfringens

“…The slopes of the gas production curves for most strains in ground frankfurter were higher than in any of the other media. Angelotti et al (1962) reported that C. perfringens grew well in meat and meat products and Busta and Schroder (1971) indicated that the rate of growth in liquid medium, in which beef was the sole protein source, was extremely rapid. Strain S-88, which was unable to produce any significant gas in casein, whole egg or R + S media, was able to grow well in ground frankfurter medium.…”

EFFECT OF MICROWAVE HEATING OF PRECOOKED CHICKEN ON Clostridiutn perfringens

“…For spore counts a 4 ml portion of a l/5 dilution of each blended sample was heat shocked in a water bath at 75°C for 20 min. Sulfite-polymyxin-sulfadiazine (SPS) agar, (Angelotti et al, 1962) was used for pour plates from serial dilutions. Plates were incubated anaerobically at 35°C for 48 hr.…”