The shift of genetic subtypes of Escherichia coli O157:H7 isolates from cattle.

ABSTRACT

A total of 46 Escherichia coli O157H7 isolates were obtained from sequential faecal samples from seven cattle collected over periods of 2 months. Nine closely related genetic subtypes, determined by pulsed-field gel electrophoresis types using three kinds of restriction endonuclease were observed among the isolates. Distinguishable, but closely related genetic subtypes can be isolated from one farm, or from one cow, should be considered when undertaking an epidemiological survey.