Surveillance for antibiotic resistant Escherichia coli in food animals.

A successful surveillance program for antibiotic resistant Escherichia coli in Australia should account for the heterogenous nature of the food-animal population. Studies that rely on measurements made on several hundred isolates can only satisfy limited objectives because they risk imprecise and biased estimation of the presence and distribution of resistance traits. Observations on a larger number of isolates are needed to ensure animal, herd and region effects are adequately represented so that findings can be extrapolated to the appropriate population of interest. An efficient methodology for measuring the resistance traits of a large number of isolates is described.