RESUMO
An enrichment broth culture-duplex PCR combination assay was devised to identify Clostridium perfringens directly from fecal samples. The method consists of a combination of short enrichment of samples in selective media, DNA isolation, and performing duplex PCR using two pairs of primers which identify C. perfringens strains that harbor the virulence enterotoxin gene. Comparison of two selective enrichment media and two incubation temperatures showed that the reinforced clostridial medium with neomycin was better than the fluid thioglycollate medium with neomycin (p<0.001); and incubation at 37 degrees C vs 45 degrees C showed no statistically significant difference (p=0.238). The optimal short time for pre-enrichment culture was 4 hours. The developed assay was applied to detect phospholipase C (plc) and enterotoxin (cpe) genes for C. perfringens in feces inoculated artificially with enterotoxigenic C. perfringens. The method could detect both gene products in samples inoculated with a minimum of 10(4) CFU per ml. When the method was applied to detect enterotoxigenic C. perfringens in 198 diarrhea patients, C. perfringens was found in 121 samples; 7 out of 121 samples were positive for both plc and cpe (prevalence of 5.8%). These results indicate that the developed assay was a suitable method for the rapid and specific detection of enterotoxigenic C. perfringens directly in fecal specimens of diarrhea patients, which will assist epidemiological investigations of food poisoning outbreaks and quality control of food products.