Ruminant gastrointestinal cell proliferation and clearance of Escherichia coli O157 : H7

Human infections,vith Escherichia coli O157:H7 cause hemorrhagic colitis th at can progress to a life-threatening sequelae, The most common mode of dis ease transmission is ingestion of contaminated bovine food products, and it is well established that E. coli O157:H7 is a transient member of the bovi ne microbiota. However, the conditions that induce acquisition and subseque nt clearance of this bacterium from the ruminant gastrointestinal tract (GI T) are not understood. Evidence that the rates of epithelial cell prolifera tion in the lower GIT of cattle are associated with the duration animals re mained E, coli O157:H7 culture positive is presented. Cattle with slower ra tes of intestinal cell proliferation in the cecum and the distal colon were culture positive significantly longer than cohort cattle with faster cell proliferation rates, Cell death rates (apoptotic indices) between the short - and long-term culture-positive animals were not different. Typical grain- based finishing diets and forage-based growing diets did not effect CIT cel l proliferation or the duration animals remained E, coli O157:H7 culture po sitive, To identify a dietary intervention that would effect GIT cell proli feration, we used sheep as a model ruminant. A fasting-refeeding regime tha t increased the rate of GIT cell proliferation was developed. The fasting-r efeeding protocol was used in cattle to test the hypothesis that feeding in terventions that increase the rate of GIT cell proliferation induce the cle arance of E, coli O157:H7 from the bovine GIT.