Vancomycin treatment failure in a vancomycin susceptible methicillin-resistant Staphylococcus aureus (MRSA) infected patient.

A 64-year old patient, who had bacteraemia, did not respond to vancomycin despite the MRSA isolate being sensitive to the antibiotic at MIC 2 microg/mL. Electron microscopy of the MRSA isolate showed thickening of the cell wall, which was not observed in MRSA with lower vancomycin MIC.