Shiga toxin-producing Escherichia coli in sheep and pre-slaughter lambs ineastern Australia

Sheep and lambs from 14 farms in southern Queensland and one from central N ew South Wales were surveyed to determine the prevalence of Shiga toxin-pro ducing Escherichia roll (STEC). STEC, isolated from 45% of 144 sheep faeces collected on the farms and 36% of 72 lamb faeces from abattoir yards, were tested for the presence of genes encoding virulence factors. Most (64%) of the 117 STEC isolates contained Shiga toxin 1 and 2 genes, 22% contained t hose encoding Shiga toxin 1, and 14% contained genes encoding Shiga toxin 2 . The genes encoding the E. coli attaching and effacing factor were present in 2.6% of STEC and 26% contained the enterohaemolysin gene. The isolates that contained the E. Loll attaching and effacing gene were serotype O157:H . This study has shown that STEC are widely distributed in eastern Australi an sheep and lambs and are shed in their faeces prior to slaughter. Thus, t here is potential for contamination of carcasses and entry of STEC into the human food chain.