Methicillin resistance was determined by disk diffusion with a 1-lg oxacillin disk, an oxacillin agar screening test (performed
when discrepancies between local laboratory and CQCM results were encountered) [12,13] and detection of the mecA
gene by PCR (performed on all MRSA isolates identified by oxacillin disk diffusion) [14]. S. aureus ATCC 29213 (methicillin-
susceptible, MSSA) and S. aureus ATCC 43300 (methicillinresistant) were included as reference strains.