[Evaluation of reduced susceptibility to vancomycin among MRSA strains isolated from clinical specimens]

In this study, a total of 390 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens between April 2004 and June 2008, in a university hospital in Zonguldak (located at Black Sea region), Turkey, were evaluated retrospectively for reduced susceptibility to vancomycin. Brain heart infusion (BHI) plates containing 4 and 6 microg/ml of vancomycin were used to screen for vancomycin intermediate S. aureus (VISA) strains. Additionally, vancomycin minimal inhibitory concentrations (MIC) of the isolates were determined by agar dilution method. No growth was observed on the screen plates after 24 and 48 hours of incubation. None of the isolates revealed MIC values equal to or higher than 2 microg/ml; MIC90 and MIC50 values were 1 microg/ml. Although VISA isolates were not detected in this study, no data was obtained for heterogeneous VISA isolates since macro-E test or population analysis were not performed. It was concluded that systematic surveillance of MRSA isolates is of particular importance to investigate the presence of VISA/hVISA isolates which may lead to treatment failures and hospital epidemics.