Ecology of staphylococci in a general medical service.

Investigation of the ecology of Staphylococcus aureus on the medical service of the Cincinnati General Hospital was carried out from 1964 to 1970. S. aureus was cultured from 1,442 patients. Overall, there was a progressive increase in the susceptibility of S. aureus to commonly used antibiotics, but not to penicillin. Hospital-acquired S. aureus remained highly resistant to all antibiotics except penicillinase-resistant penicillins. There was a progressive decline in the percentage of hospital-acquired infections from January 1964 to September 1969, followed by a rise during September 1969 to September 1970. No single bacteriophage group predominated among nosocomially acquired S. aureus. Major changes in the hospital environment did not appear to influence the prevalence of nasal carriage or hospital acquisition of S. aureus. This study identified the continuing problem of acquisition of S. aureus in the hospital, but no specific "epidemic strain."