Glycopeptides and Linezolid MIC Changes in Staphylococcus aureus and Coagulase-Negative Staphylococci Isolates From 2008-2011

Abstract

Aims: Glycopeptides and linezolid are the antimicrobial agents used for the treatment of methicillin resistant Staphylococcus aureus (MRSA) and methicillin resistant Coagulase negative Staphylococci (MRCoNS) infections. It is emerging concern about an increase minimum inhibitor concentration (MIC) of vacomycin among S. aureus strains. In this study, we aimed to analyse the trends in MICs of vancomycin, teicoplanin and linezolid over 4 years (2008-2011) period. Materials and methods: Identification and MICs of the isolates were tested in Vitek2 Compaktand Phoenix (Becton Dickinson, Diagnostic Systems, USA) automated systems. MIC50 (defined as the minimum concentration at which 50% of the isolates were inhibited), MIC90 (defined as the minimum concentration at which 90% of the isolates were inhibited) and mean MICs were evaluated. All calculations were performed for each year. Results and conclusion: No vancomycin, teicoplanin and linezolid resistant isolates were detected. The decreased in the mean MIC of vancomycin in S. aureus isolates over 4 years, was found significant. The increased, in the mean MIC of vancomycin in CoNS isolates among 2008-2009, was significant. Otherwise, the decrease in the mean MIC of teicoplanin and linezolid in S. aureus isolates, was significant among 2009-2010.