Diversity of isolates of Rhodococcus equi from Australian Thoroughbred horse farms

Pulsed field gel electrophoresis of restriction endonuclease digested genom ic DNA from a collection of clinical isolates of Rhodococcus equi was used to compare strain diversity on different Thoroughbred horse farms over time . Restricted diversity was found among the isolates tested, as the same str ains were detected on multiple farms and in multiple years. Marked variatio n occurred in strain prevalence with some strains being represented by sing le isolates, and the most prevalent by 26 isolates. There were dominant str ains on some farms and the prevalence of some strains differed between farm s. Infection with multiple strains was noted in some cases where multiple i solates from a single foal were examined.