The genotypic changes and clonal turnover of EHEC O157:H7 in cattle have already been reported. So, we attempted to inoculate and genotype EHEC O26:H11 in two cattle. A total of 479 isolated strains of the inoculated strain were recovered from cattle and their environment and genotyped by Pulse-field gel electrophoresis (PFGE) with Bln I and Spe I restriction enzyme. As a result, all isolated strains were mutated and classified to 15 subtypes by combination of two restriction enzyme patterns. The largest difference was 5 bands at one enzyme. The results that up to 5 band differences were observed should be considered when undertaking an epidemiological survey using PFGE. (Zoonosis Section, Department of Safety Research TEL +81-298-38-7816)
