Evaluation of vancomycin MIC creep in methicillin-resistant Staphylococcus aureus infections-a systematic review and meta-analysis

Abstract

Objectives: Vancomycin is currently the primary option treatment for methicillin-resistant Staphylococcus aureus (MRSA). However, an increasing number of MRSA isolates with high MICs, within the susceptible range (vancomycin MIC creep), are being reported worldwide. Resorting to a meta-analysis approach, this study aims to assess the evidence of vancomycin MIC creep.

Methods: We searched for studies in the PubMed database. The inclusion criteria for study eligibility included the possibility of retrieving the reported data values of vancomycin MIC and information concerning the applied MIC methodology.

Results: The mean values of vancomycin MICs, of all 29 234 S. aureus isolates reported in the 55 studies included in the meta-analysis, were 1.23 mg/L (95% CI 1.13-1.33) and 1.20 mg/L (95% CI 1.13-1.28) determined by Etest and broth microdilution method, respectively. No significant differences were observed between these two methodologies. We found negative correlation between pooled mean/pooled proportion and time strata.

Conclusions: We have found no evidence of the MIC creep phenomenon.

Keywords: MIC creep; MIC methodologies; Meta-analysis; Staphylococcus aureus; Vancomycin.