Evaluation of the BBL® CrystalTM MRSA ID System for Rapid Detection of Methicillin Resistance in Staphylococcus aureus

Twenty-four clinical isolates of Staphylococcus aureus collected from various geographic areas and four reference strains were studied by (i) agar diffusion with disks impregnated with 5 μg oxacillin and reading after incubation at 30°C for 24 hours, (ii) Southern hybridization with a probe specific for the mecA gene, and (iii) the BBL® Crystal^TM MRSA ID system. There was perfect correlation between the three methods: the BBL® Crystal^TM MRSA ID system detected methicillin resistance in the fifteen strains hybridizing with the mecA probe and classified as resistant by the oxacillin disk diffusion test; the thirteen remaining strains were susceptible by agar diffusion and by the BBL® test and did not hybridize with the mecA probe. The BBL® Crystal^TM MRSA ID System, therefore, appears to be an accurate method for rapid detection of Staphylococcus aureus exhibiting homogeneous resistance to methicillin.