Alteration of cutaneous staphylococcal flora as a consequence of antimicrobial prophylaxis.

Antimicrobial agents given as prophylaxis have profound effects on the microbial flora of the skin. Coagulase-negative staphylococci cultured from the skin of patients after cardiac surgery have been found to be more resistant to antimicrobial drugs than organisms cultured from the same skin sites preoperatively. Evidence exists both for the selection of resistant organisms from the preoperative flora and for the postoperative acquisition of such organisms from the nosocomial environment. Staphylococci causing postoperative infections have the same antimicrobial resistance phenotypes as do colonizing isolates; this observation suggests that colonized patients and hospital staff make up a nosocomial reservoir for resistant organisms.