AbstractsBiology & Animal Science

Escherichia coli O157:H7 is a major foodborne human pathogen that causes disease worldwide. Healthy cattle are the primary reservoir of this bacterium and the amount and frequency of E. coli O157:H7 shedding varies among individual cattle. The term “super-shedder” has been applied to cattle that are transiently high shedders (≥104 CFU/g feces). Targeting these cattle for mitigation strategies has been proposed as a means of reducing the incidence and spread of E. coli O157:H7 in the feedlot environment. The objectives of this study were to determine the frequency and duration of the super-shedding state in cattle; and to elucidate phenotypic or genetic differences among E. coli O157:H7 isolates recovered from super-shedding cattle and low-shedder cattle. It was found that the super-shedding state is short lived and lacks continuity and we were unable to successfully identify specific traits among super-shedder isolates that could be used to differentiate them from low-shedder isolates.