Recognition and importance of Staphylococcus epidermidis infections

The bacteriology, epidemiology, pathogenesis, clinical features, antimicrobial susceptibility, and therapy of Staphylococcus epidermidis infections are reviewed. Staph. epidermidis is often regarded as a culture contaminant, but its importance as a pathogen has been recognized in recent years. Except for native-valve endocarditis, most Staph. epidermidis infections are hospital-acquired. Staph. epidermidis is a common cause of infections involving indwelling foreign devices, surgical wound infections, and bacteremia in immunocompromised patients. The occult nature of these infections and low virulence of the organism make diagnosis and treatment difficult. Staph. epidermidis isolates from nosocomial infections frequently are resistant to methicillin; however, resistant isolates often appear to be susceptible to methicillin unless reliable methods of susceptibility testing are used. Cross-resistance between methicillin and cephalosporins occurs in vitro. Virtually all Staph. epidermidis isolates are susceptible in vitro to vancomycin and rifampin. Penicillin G, semisynthetic penicillinase-resistant penicillins, and cephalosporins are effective for the treatment of methicillin-sensitive Staph. epidermidis infections. Vancomycin is the drug of choice for infections caused by methicillin-resistant organisms. Vancomycin, combined with rifampin or gentamicin, or both, is recommended for therapy of serious infections caused by methicillin-resistant strains. Staph. epidermidis is an important pathogen in immunocompromised patients and patients who develop nosocomial bacteremia; treatment usually consists of antimicrobial therapy and removal of indwelling catheters or devices.