INVITRO ACTIVITY OF VANCOMYCIN AND TEICOPLANIN ON GRAM-POSITIVE COCCI

The activities of vancomycin and teicoplanin against 148 strains of Gram-positive cocci were tested using agar diffusion and liquid microdilution MIC determination. Tested strains included 84 staphylococci, 32 S. aureus, 52 coagulase-negative staphylococci (CNS), 52 enterococci, and 12 streptococci. Most strains (136) were susceptibe to both agents, with inhibition diameters of 17 mm or more. MRSA strains exhibited lower geometric MIC means with teicoplanin (0.90-mu-g/ml) than with vancomycin (1.79-mu-g/ml); this difference was found for methicillin-susceptible S. aureus strains (1.07 and 1.38-mu-g/ml for teicoplanin and vancomycin, respectively). In contrast, methicillin-susceptible and methicillin-resistant strains of CNS exhibited similar MICs (1.60-mu-g/ml approximately). Enterococci were more susceptible to teicoplanin (MIC 0.25-mu-g/ml) than to vancomycin (MIC 1.35-mu-g/ml). Both vancomycin and teicoplanin were thus found to be consistently effective against Gram-positive cocci ; however, teicoplanin proved more effective than vancomycin against enterococci and methicillin-resistant S. aureus strains and may therefore be a valuable therapeutic alternative for these multiresistant organisms.