THE RELIABILITY OF MICROSCAN(TM) CONVENTIONAL AND RAPID PANELS TO IDENTIFY STAPHYLOCOCCUS-AUREUS AND DETECT METHICILLIN RESISTANCE - AN EVALUATION USING THE TUBE COAGULASE TEST AND MECA PCR

Microscan(TM) (Dade Diagnostics, Brisbane) Positive Combo Type 6 (312 panels) and Rapid Positive Breakpoint Type 1 (62 panels) were evaluate d for Staphylococcus aureus identification, using the tube coagulase t est (TC), and oxacillin susceptibility, using mecA. A total of 374 con secutive clinical staphylococci were tested, with TC and Microscan(TM) having 100% correlation (335 identified as S. aureus and 39 as coagul ase negative staphylococci by both methods). A 93% correlation was obs erved between Microscan(TM) and mecA PCR for oxacillin susceptibility. No very major errors (0/374 false oxacillin susceptibility) and 26 (7 %) major errors (26/374 false oxacillin resistance) were found showing false resistance to oxacillin to be a problem in our population. Oxac illin Etest (AB Biodisk, Sweden) was performed on all oxacillin resist ant isolates. A bimodal distribution was observed between mecA positiv e and negative isolates. A testing algorithm (using the Microscan(TM) panels and Etest) was developed for this laboratory to detect mecA enc oded methicillin resistance. Retrospective application of this algorit hm to the 374 isolates gave 100% correlation with mecA detection.