Comparison of vancomycin pharmacodynamics (1 g every 12 or 24 h) against methicillin-resistant staphylococci

This study compared the duration of serum bactericidal activity for vancomy cin, 1 g every 12 or 24 h at steady state, against methicillin-resistant St aphylococcus aureus (MRSA) and coagulase-negative staphylococci (MR-CNS). A ll four test isolates were susceptible to vancomycin with minimal inhibitor y concentration (MIC) values of either 2 or 4 mg/l. Serum bactericidal titr es (SBTs) were run in duplicate and serum bactericidal activity (SBA) was d efined as the time points at which all subject SBTs were greater than or eq ual to 1:2. For the every 12-h regimen, SEA was 10-12 h. With the every 24- h regimen, the duration of SEA was 10-16 h for MRSA and 8-10 h for MR-CNS. The pharmacodynamic data suggest that for those with good renal function a Q12h dosing interval is most appropriate for MR-CNS or staphylococcal isola tes with MICs of 4. (C) 2000 Elsevier Science B.V. and International Societ y of Chemotherapy. All rights reserved.