Bovine Escherichia coli O157:H7 Infection Model

Cattle are a major source of Shiga toxin-producing Escherichia coli (STEC) O157:H7 and other STEC that cause serious food-borne diseases in humans. Most STEC-infected cattle are asymptomatic carriers of STEC. We have developed bovine STEC-infection models to identify the bacterial and host factors that are integral to intestinal colonization and shedding of STEC by cattle. Although STEC usually does not cause disease in cattle, experimentally infected colostrum-deprived, neonatal (<12 h old) calves develop diarrhea and enterocolitis by 18 h after inoculation with 10¹⁰ colony-forming units (CFUs) of STEC bacteria. STEC-infected calves become colonized with bacteria (i.e., have ≥ 10⁶ CFUs of inoculum bacteria/g of intestinal tissue or feces) and have attaching and effacing lesions in both the small and large intestines (1 ,2 ). In some calves, the disease induced by STEC may be fatal.