EVALUATION OF RAPID ATB STAPH FOR 5-HOUR ANTIMICROBIAL SUSCEPTIBILITYTESTING OF STAPHYLOCOCCUS-AUREUS

The accuracy of Rapid ATE Staph (bioMerieux, La Balme-Les Grottes, Pra nce) for detection of oxacillin resistance and for detection of suscep tibility to 11 other antimicrobial agents in 553 and 519 Staphylococcu s aureus isolates, respectively, was evaluated by comparing results wi th those produced by oxacillin agar screen and agar dilution methods, respectively, Further characterization of isolates with discrepant res ults for oxacillin testing was done by PCR detection of the nuc and me cA genes. By oxacillin agar screening, there were 307 oxacillin-resist ant and 246 oxacillin-susceptible isolates, Rapid ATE results were obt ained in 5 h for 515 (93.2%) of the isolates tested, Rapid ATE showed 97.0% sensitivity for detection of oxacillin resistance, confirmed by the presence of the mecA gene, After repeat testing of isolates flagge d by the ATE software as possible errors, sensitivity increased to 99% for oxacillin-resistant isolates. Essential agreement with agar dilut ion testing for susceptibility to amoxicillin-clavulanic acid, gentami cin, erythromycin, clindamycin, and ciprofloxacin, as estimated by You den's J statistic, was >0.90, Subpoputations of isolates with signific antly increased MICs of amikacin, rifampin, and minocycline, indicatin g borderline susceptibility, were detected by Rapid ATE and categorize d as resistant, Rapid ATE Staph showed adequate accuracy for detection within 5 h of the oxacillin- and multiple-drug-resistant S. aureus is olates currently prevalent in Belgium.