Effect of culture conditions on Escherichia coli O157:H7-mediated attaching-effacing lesions in a bovine large intestinal mucosal explant model.

The effects of culture conditions on the extent of Escherichia coli O157:H7 attaching-effacing (A/E) adherence in an adult bovine large intestinal mucosal explant model were assessed by three different morphometric methods. Measurement of the percent of tissue sections with A/E adherence and the number of foci of A/E adherence mm(-1) of surface epithelium was more sensitive than measurement of the percent of surface epithelium with A/E adherent bacteria for detection of treatment effects. Culture of bacterial inoculum in tryptic soy broth, incubation of explants in 5% CO(2), and rocking of explants on a platform rocker at 18 cycles min(-1) provided optimal conditions for A/E adherence. In future studies, the model may be used for preliminary testing of intervention strategies aimed at reduction of E. coli O157:H7 intestinal colonization of cattle.