DISTINCT GENOTYPIC CLUSTERS OF HETEROGENEOUSLY AND HOMOGENEOUSLY METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS FROM A GREEK HOSPITAL

Methicillin-resistant Staphylococcus aureus (MRSA) strains isolated ov er a one-year period from a Greek hospital were tested for their level s of resistance to methicillin by population analysis. Heterogeneously resistant strains belonged to classes I, II, and II/III, whereas homo geneously resistant ones belonged to class IV. Strains of all classes possessed the mecA gene. Pulsed-field gel electrophoresis (PFGE) of Sm al-digested genomic DNA revealed that all heterogeneously resistant st rains were related. Homogeneously resistant strains were also closely related, but in a cluster distinct from the heterogeneous one. The met hicillin-sensitive strains displayed a greater variety of PFGE types c ompared to MRSA isolates.