Objective: In this study, it was aimed to investigate the rate of reduced susceptibility to vancomycin in methicillin resistant S. aureus (MRSA) and methicillin sensitive S. aureus (MSSA) isolates.

Materials and Methods: A total of 131 S. aureus (45 MRSA and 86 MSSA) strains isolated from various clinical specimens in medical microbiology department of Faculty of Medicine Bolu Abant İzzet Baysal University, Bolu were studied. Brain heart infusion agar medium containing 4 μg/ml and 6 μg/ml vancomycin was used for the investigation of vancomycin intermediate Staphylococcus aureus (VISA). Growth was assessed at 24th and 48th hour of cultivation. Microdilution method was used for the determination of vancomycin minimal inhibitory concentration (MIC) values. Vancomycin MIC values were evaluated for S. aureus according to Clinical Laboratory Standarts Institute guidelines. Mu3 hVISA, S. aureus ATCC 29213 (vancomycin sensitive), and vancomycin resistant Enterococcus faecalis which have been defined by conventional methods and the automated system (BD Phoenix 100, USA) in our laboratory were used as quality control strains.

Results: In the study, no growth was observed on the screening medium. Vancomycin MIC values of all isolates were found to be between the range of 0.25 to 2 μg/ml. MIC90 and MIC50 values were expressed in 1 μg/ml. MIC values of vancomycin were found to be 1 μg/ml for S. aureus, 4 μg/ml for Mu3 hVISA strain, and >16 μg/ml for the Enterococcus faecalis strain.

Conclusion: Decreased susceptibility to vancomycin was detected in none of the S. aureus strains in this study. Continuous surveillance of vancomycin resistance in S.aureus strains with screening methods will be useful in terms of infection control and epidemiological measures.