Antibiotic policy and spread of Staphylococcus aureus strains in Danish hospitals, 1969-1974.

In the period 1969-1974 a decreasing number of Danish hospital departments recorded epidemic occurrences of Staphylococcus aureus strains, and the local spread of strains was less extensive. Multiple-resistant strains of the 83 A complex were succeeded by type 94 strains, resistant to penicillin only. The level of methicillin resistance fell from 19 to 6%. 12% of methicillin resistant strains are now sensitive to streptomycin and/or tetracyclines; they do not represent a few clones, but belong to a wide spectrum of phage types. The changes follow a reduction in the consumption of streptomycin and tetracyclines not of methicillin or other penicillins. As a contrast to the general reduction of combined resistance to streptomycin and tetracyclines, the strains in dermatological departments, where tetracyclines are commonly used, maintain a high degree of resistance to tetracyclines alone.