ESCHERICHIA-COLI O157-H7 IN MICROBIAL-FLORA OF SHEEP

We found naturally occurring, potentially virulent Escherichia coli O1 57:H7 strains in sheep. The incidence of E. coli O157:H7 was transient and ranged from 31% of sheep in June to none in November. The use of a sensitive culture technique and the choice of the proper sampling se ason were both essential for detecting this bacterium in sheep. DNA hy bridizations showed that 80% of the E. coli O157:H7 isolates had at le ast two of the Shiga-like toxin types I or II or the attaching-effacin g lesion genes.