Assessing the efficacy of within-animal control strategies against E. coli O157: a simulation study.

A stochastic simulation model was used to assess the efficacy of potential measures to control the levels of Escherichia coli O157 within the bovine host. The model described E. coli O157 population sizes at several sites along the bovine gut and therefore only interventions that operate at an individual animal level could be evaluated. In order to use the model to evaluate the control strategies, it was necessary to make assumptions about how each strategy affected E. coli O157 populations in vivo. The within-animal conditions under these control strategies were modelled by adjusting the growth rates of E. coli O157 at specific sites of interest in the gut, based on these assumptions. The model simulated the population dynamics of an initial dose of E. coli O157 inoculated into an animal in the presence of inhibitory probiotics or antibiotics, bactericidal antibiotics or probiotics, and following fasting. Of the control strategies considered, the use of inhibitory probiotics appeared most promising and continued development of a suitable product is to be encouraged.