EVALUATION OF BBL CRYSTAL MRSA ID SYSTEM

The BBL Crystal system (Becton Dickinson Microbiology Systems, Cockeys ville, Md.) was evaluated for its accuracy in identifying oxacillin re sistance in Staphylococcus aureus by testing of mec-specific-gene-posi tive and -negative isolates. Although the manufacturer makes no claim for use of the product for testing of staphylococci other than S. aure us, the product's potential utility in detecting oxacillin resistance in isolates of mec gene-positive and -negative Staphylococcus epidermi dis was also explored. All mec gene-negative staphylococci yielded a n egative MRSA ID test reaction. There was a close correlation between m ec gene positivity and a positive reaction in the methicillin-resistan t S. aureus identification system with 63 of 69 (91%) stock isolates o f S, aureus yielding a positive result in 4 h, 66 of 69 (95%) yielding a positive result in 5 h, and 68 of 69 (99%) yielding a positive resu lt in 6 h. The corresponding percentage agreements at 4, 5, and 6 h fo r mec gene-positive stock isolates of S. epidermidis were 87, 98, and 96%, respectively.