In-vitro teicoplanin-resistance in coagulase-negative staphylococci from patients with endocarditis and from a cardiac surgery unit

Abstract

Among 31 strains of coagulase-negative staphylococcus (CNS) causing endocarditis in individual patients, 16 had MIC of teicoplanin greater than or equal to 8 mg/l (MIC50, 8; MIC90, 8; MIC range, 0.5-32 mg/l); and 24 had MBC greater than or equal to 16 mg/l (MBC50, 32; MBC90, 64; MBC range, 4-128 mg/l). Greater sensitivity was shown to vancomycin (MIC50, 2; MIC90, 4; MIC range, 1-8 mg/l; MBC50, 2; MBC90, 4; MBC range, 0.5-8 mg/l). Teicoplanin-resistant CNS (MIC, greater than or equal to 8 mg/l) were detected in the anterior nares of two of three patients and six of nine staff, and in the air, of a cardiac surgery unit, and in other series of CNS of clinical origin. The results of in-vitro sensitivity testing of CNS to teicoplanin are dependent on the media and conditions used, and their clinical significance has not been determined. Nevertheless, the findings reported here put in question the use of teicoplanin alone as prophylaxis during valve replacement surgery.