Staphylococcus aureus strains of the 94/96 complex isolated in the German Democratic Republic: incidence and discrimination of strain clones.

The incidence of S. aureus with a phage pattern of 94/96 rose from 9% in 1979 to 18% in 1985. The frequency of occurrence not only increased among isolates from inpatients and outpatients but also among those from healthy carriers. All of the 504 investigated strains of different origin exhibited a uniform pattern of biochemical characteristics. In each of 40 investigated strains, a plasmid with a molecular mass of 16 Md was found. Elimination experiments indicated that these plasmids determined resistance to penicillin and/or cadmium. Resistance to chloramphenicol was found to be determined by plasmids of 2.0 Md, resistance to oxytetracycline by plasmids of 2.7 Md. Clones could be discriminated by means of 7 experimental phages. The application of these phages for typing strains from infections in hospitals is demonstrated.