Identifying Factors that Promote Clearance of E. coli O157:H7 from Cattle

Escherichia coli O157:H7 foodbome illness results in hemorrhagic colitis that can lead to life-threatening complications. Human disease has followed consumption of contaminated under-cooked ground beef, unpasteurized dairy products, vegetables, unpasteurized apple cider, drinking water or recreational water. Healthy cattle carry E. coli O157:H7 into processing plants and disperse this human pathogen in the environment. Decreasing the incidence of E. coliO157:H7-positive cattle will decrease the incidence of human disease. The average duration an individual animal is culture-positive for E. coli O157:H7 is 30 days, but the ranges in duration individual animals are culture-positive vary from a few days to one year. The conditions that induce acquisition of E. coli O157:H7, prolong or curtail its presence, and cause its clearance from the ruminant gastrointestinal tract (GIT) are not understood.
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This research will test the hypothesis that cattle diet and colonic cell proliferation may be used in pre-harvest interventions to promote the clearance of E. coli O157:H7 from the GIT of cattle. Our first objective is to expand our observations that grain diets promote clearance of E.coli O157:H7 from the ruminant gastrointestinal tract and determine the natural mechanism(s) that influence the clearance of these bacteria. Our second objective is to confirm our preliminary data that epithelial cell proliferation in the lower GIT promotes rapid clearance of E. coli O157:H7 from ruminants. This research directly contributes to the USDA NRICGP Food Safety program goals of decreasing the incidence of food-bome illness by increasing our understanding of the ecology of E.coli O157:H7.