Bactericidal activity of daptomycin, vancomycin, teicoplanin and linezolid against S taphylococcus aureus, Enterococcus faecalis and Enterococcus faecium using human peak free serum drug concentrations

Abstract

The bactericidal activities of daptomycin, vancomycin, teicoplanin and linezolid at human peak free serum concentrations ( C max,free) were determined against Staphylococcus aureus (one methicillin-susceptible and two methicillin-resistant strains), Enterococcus faecalis and Enterococcus faecium (one vancomycin-susceptible and one vancomycin-resistant strain of each). Daptomycin was rapidly bactericidal against 7/7 strains at C max,free of 22.0 mg/L (corresponding to 63% protein binding) and against 3/7 strains at 4.8 mg/L (corresponding to 92% protein binding). Vancomycin (18.0 mg/L) was bactericidal against only two strains. Both teicoplanin (4.5 mg/L) and linezolid (10.4 mg/L) were consistently bacteriostatic. Daptomycin is a useful option for the treatment of Gram-positive infections owing to its strong bactericidal activity.