Most probable numbers of enterotoxigenic Clostridium perfringens in intestinal contents of domestic livestock detected by nested PCR.

The incidence and numbers of enterotoxigenic Clostridium perfringens in the intestinal contents of cattle, swine and broiler chickens were determined and compared with those of total (enterotoxigenic and nonenterotoxigenic) C. perfringens. The method used for the enumeration of enterotoxigenic C. perfringens consisted of a combination of the most probable number (MPN) method and a nested polymerase chain reaction after enrichment culture of the sample. Enterotoxigenic C. perfringens was found in 26% (4.0 x 10-4.3 x 10(2) MPN/100 g), 22% (4.0 x 10-2.3 x 10(3) MPN/100 g) and 40% (4.0 x 10-2.4 x 10(4) MPN/100 g) of intestinal contents of 50 head each of cattle, swine and broiler chickens, respectively. Whereas, total C. perfringens was found in 76% (9.0 x 10-7.5 x 10(6) MPN/100 g), 44% (7.0 x 10-4.3 x 10(6) MPN/100 g) and 80% (4.3 x 10(2)-9.3 x 10(7) MPN/100 g) of intestinal contents of 50 head each of cattle, swine and broiler chickens, respectively, by the conventional MPN method. In all cases, enterotoxigenic cells were not dominant in the population of C. perfringens: a small number of enterotoxigenic cells of C. perfringens co-existed with a large number of nonenterotoxigenic cells in the same sample. The ratios of enterotoxigenic C. perfringens cells to total C. perfringens cells were 1/10-1/10(5).