Clinically significant coagulase-negative staphylococci: identification and resistance patterns.

Coagulase-negative staphylococci (CNS) of clinical significance, isolated from 131 patients, were investigated during the period 1989-90 in northern Norway. The staphylococci were isolated from blood cultures (68; 51.9%), vascular catheters (6), osteomyelitis foci (13), postoperative and other wounds (15), and urine samples (29). The use of Gram-positive Identification Card (Vitek) and 'Staph-zym' (Rosco) both gave a primarily correct species identification in 95% of the cases. Staphylococcus epidermidis was the predominant species (72.3%). Methicillin-resistance was found in 40 of 131 (30.5%) of all CNS and in 34 of 96 (35.4%) of S. epidermidis. Methicillin-resistant (MR) S. epidermidis strains were usually resistant to gentamicin, tetracycline, chloramphenicol and trimethoprim. MR strains were, however, less resistant to sulphonamides than methicillin-sensitive strains (10 out of 34 vs. 55 out of 62). Methicillin-resistance implied resistance to all beta-lactam antibiotics, including imipenem. Among S. epidermidis, MR isolates increased from 10% in 1987 to 35.4% in 1989-90. All strains were sensitive to vancomycin and rifampicin.