Background: Increase of immunocompromised patients and frequent use of indwelling catheters cause staphylococcal bacteremia, especially due to coagulase-negative staphylococci (CNS), in contrast with Staphylococcus aureus in the past. And, infections of methicillin-resistant staphylococci have been increasing in number from 1970s. In this study, species of staphylococcal isolates from blood were demonstrated, and their methicillin susceptibilities were evaluated for the empirical choice of antibiotics.

Methods : One hundred and seventy-five staphylococcal strains isolated from blood culture at Pusan National University Hospital during the year 1999 were included. Species identification, susceptibility tests by agar dilution and disk diffusion methods, and mecA gene detection by polymerase chain reaction were performed.

Results : S. aureus (41%), S. epidermidis (30%), S. auricuralis, S. intermedius, S. haemolyticus, S. capitis, S. simulans, S. sciuri, S. homis, and S. warneri were identified. Thirty-one stains (43.4%) of S. aureus, 43 stains (83%) of S. epidermidis, and 24 stains (46%) of other CNS are resistant to oxacllin. The results of disk diffusion test were consistant with agar dilution tests in all S. aureus strains and 95.5% of CNS strains. The results of mecA gene detection were consistant with agar dilution methods in 96.8% of S. aureus and 89.6% of CNS.

Conclusions : Not only S. aureus and S. epidermidis but also other various species of staphylococci were recovered from blood, and methicillin-resistant strains reached 43.2% of S. aureus, and 64.4% of CNS. These results would help for physicians to choose primary empirical therapeutic agents of patients who are suggestive of staphylococcal bacteremia. (Korean J Clin Microbiol 2001;4:52-57)