Abstract
Multiply- and methicillin-resistant Staphylococcus aureus (MRSA) strains have been isolated from five small outbreaks of nosocomial infection in five different hospitals. The MRSA were typed by phage patterns, biochemical traits, resistance phenotypes and plasmid patterns. Three different groups of strains can be distinguished. The MRSA from three outbreaks in one country share identical characters. Phage typing by the use of the International Basic Set for Phage Typing staphylococci as well as experimental phages does not completely discriminate between the strains. Attribution of several resistance determinants to plasmids in two of the described strain groups proved valuable for strain differentiation. These multiply-resistant strains are sensitive to vancomycin and to rifampicin.