Long-Term Survival of Shiga Toxin-Producing Escherichia coli O26, O111, and O157 in Bovine Feces

Cattle are an important reservoir of Shiga toxin-producing Escherichia coli (STEC) O26, O111, and O157. The fate of these pathogens in bovine feces at 5, 15, and 25°C was examined. The feces of a cow naturally infected with STEC O26:H11 and two STEC-free cows were studied. STEC O26, O111, and O157 were inoculated into bovine feces at 10¹, 10³, and 10⁵ CFU/g. All three pathogens survived at 5 and 25°C for 1 to 4 weeks and at 15°C for 1 to 8 weeks when inoculated at the low concentration. On samples inoculated with the middle and high concentrations, O26, O111, and O157 survived at 25°C for 3 to 12 weeks, at 15°C for 1 to 18 weeks, and at 5°C for 2 to 14 weeks, respectively. Therefore, these pathogens can survive in feces for a long time, especially at 15°C. The surprising long-term survival of STEC O26, O111, and O157 in bovine feces shows that such feces are a potential vehicle for transmitting not only O157 but also O26 and O111 to cattle, food, and the environment. Appropriate handling of bovine feces is emphasized.