[Genotyping of clinical isolates of MRSA by PFGE and AP-PCR].

Genotyping of 67 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) separated from patients in a hospital in Mizusawa City in 1994 and 1995 was studied by pulsed field gel electrophoresis (PFGE) and arbitrarily primed-polymerase chain reaction (AP-PCR). Two main genotypes were observed by PFGE, and more than 70% of the 67 MRSA isolates produced coagulase type II. One group diverged well and gained higher tolerance in 1994, but was not isolated in 1995. The other group was continually isolated during the two-year period and showed moderate tolerance in 1994, and higher tolerance in 1995. AP-PCR was able to classify the genotypes of MRSA into 6 subgenotypes under the present conditions, which supported the results obtained by PFGE. These results suggest that AP-PCR could become a convenient and useful typing method by improving both sequence and length of a primer.