Molecular epidemiology of multiresistant Staphylococcus aureus in Australian hospitals

Microbiology Department, Monash University, Clayton, Victoria, Australia, 3168 * Correspondence and requests for reprints should be sent to Dr R. A. Skurray. Received April 26, 1983 Accepted July 22, 1983 SUMMARY. Antibiotic multiresistant isolates of Staphylococcus aureus from outbreaks of nosocomial infection throughout Australia were found to possess essentially similar patterns of antibiotic resistance. Plasmid DNA profiles from these isolates exhibited a common pattern of large plasmids, of (15-22) x 10 6 mol. wt, associated with resistance to gentamicin, kanamycin and tobramycin, plasmids of 3 x 10 6 mol. wt, mediating resistance to chloramphenicol, and cryptic plasmids of 1 x 10 6 mol. wt. Restriction endonuclease digestion confirmed the presence of related plasmids in isolates from all the hospitals that were surveyed. The homogeneity of these organisms suggests the dissemination of a multiresistant, plasmid-bearing strain of S. aureus , or its derivatives, among geographically-separated hospitals in Australia.