Rapid detection of methicillin resistance in coagulase-negative staphylococci by commercially available fluorescence test.

A commercially available fluorescence test (Crystal MRSA ID System; BBL) for the rapid detection of methicillin resistance in Staphylococcus aureus was evaluated for the detection of methicillin resistance in coagulase-negative staphylococci. The assay was compared with the agar dilution method and mecA detection by PCR. Provided that one uses an inoculum equivalent to a no. 2 McFarland standard instead of a no. 0.5 McFarland standard, which is used for S. aureus, the Crystal MRSA ID System detects methicillin resistance among coagulase-negative staphylococci with sensitivity, specificity, and positive and negative predictive values of 98.5, 95.4, 96.3, and 98.1%, respectively.