GENOMIC VARIABILITY OF STAPHYLOCOCCUS-AUREUS AND THE OTHER COAGULASE-POSITIVE STAPHYLOCOCCUS SPECIES ESTIMATED BY MACRORESTRICTION ANALYSISUSING PULSED-FIELD GEL-ELECTROPHORESIS

The genomic DNAs of 95 culture collection and hospital Staphylococcus aureus subsp, aureus strains of various origins, as well as the genomi c DNAs of other coagulase-positive Staphylococcus species, were cleave d with restriction endonuclease SmaI and subjected to pulsed-field gel electrophoresis. The levels of similarity of the SmaI restriction pat terns of the S, aureus subsp. aureus strains varied from 30 to 100%, w hich is considered characteristic of this species; thus, these organis ms belonged to the same species restriction group, Within this range o f similarity values 13 S, aureus intraspecies restriction groups were identified, and each group consisted of strains whose levels of simila rity ranged from 65 to 100%, S. aureus subsp, aureus CCM 885(T) (T = t ype strain) belonged to the major intraspecies restriction group that comprised 39% of the S, aureus strains which we studied, The strains o f the other coagulase-positive staphylococci, including Staphylococcus aureus subsp, anaerobius, Staphylococcus hyicus, Staphylococcus inter medius, Staphylococcus delphini, and Staphylococcus schleiferi subsp, coagulans, clustered with their type strains in separate restriction g roups, S, aureus subsp, aureus exhibited almost no similarity to these species, We found 44-kb SmaI fragments in all of the S, aureus subsp, aureus and S, aureus subsp, anaerobius strains studied, and these fra gments are considered characteristic of the species S. aureus. The hig h level of homolog of these fragments was confirmed by the results of DNA hybridization experiments in which we used representatives of indi vidual intraspecies restriction groups. Of the other staphylococci stu died, only Staphylococcus epidermidis and one strain of S, hyicus cont ained these fragments, However, the levels of homology between these f ragments and the fragments of S, aureus were found to be very low.