Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 2/2/1998
Publication Date: N/A
Technical Abstract: Cattle are an important reservoir of Escherichia coli O157:H7 and other enterohemorrhagic E. coli that cause hemorrhagic colitis and hemolytic uremic syndrome in humans. Both dairy and beef cattle are sporadically and asymptomatically infected with this organism and can shed E. coli O157:H7 long-term. We showed that neonatal calves <36 h old developed diarrhea and enterocolitis with attaching and effacing (A/E) lesions in both the large and small intestines by 18 h after inoculation with E. coli O157:H7. The severity of diarrhea and inflammation and the frequency and extent of A/E lesions increased by 3 d after inoculation and also were greater in calves inoculated before 12 h of age than in calves inoculated at 36 h of age. Weaned calves inoculated with E. coli O157:H7 after 48 h fasting did not develop diarrhea. However, 3 of 7 calves had A/E lesions in the large intestine and high levels of E. coli O157:H7 in feces. Intimin, an outer membrane adhesion protein, was required for the production of diarrhea and A/E lesions by E. coli O157:H7 in neonatal calves. Shiga toxin was not required for E. coli O157:H7 pathogenicity in neonatal calves, but Shiga toxin-producing strains colonized weaned calves better than did Shiga toxin-negative strains. Bovine models of E. coli O157:H7 infections are relevant for studying the pathogenesis of E. coli O157:H7 infections in cattle. These models will be useful for identifying ways to reduce the prevalence of E. coli O157:H7 in cattle and thus reduce the risk of E. coli O157:H7 disease in humans.