CONVENTIONAL VERSUS MOLECULAR TESTS (MULTIPLEX PCR AND PCR MECA GENE) FOR DETECTION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS

In this study, for detection of methicillin-resistant S. aureus (MRSA), a mecA multiplex PCR-based amplification was compared with the 1 mu g oxacillin disk diffusion test, detection of minimal inhibitory concentration (MIC), and screening in agar with 4% NaCl and 6 mu g/mL oxacillin. Among 24 isolates obtained from blood, mecA gene was detected in only 16 (66.7%) isolates by multiplex PCR. The MIC test showed a range of resistance to oxacillin from 0.19 to 512 mu g/mL, among these isolates. Data obtained by screening and dilution tests showed that sensitivity to methicillin was 80.0% and 72.8%, respectively, when compared with the presence of mecA gene (multiplex). All isolates, including the negatives, when revaluated for mecA gene by PCR were positive. P-lactamase production was positive for 20/25 isolates (80.0%). About 1/4 of patients died dispite most of them (83.3%) were adequately treated. The simultaneous identification of the bacteria and determination of this susceptibility to antibiotics are necessary for the choice of empiric antibiotic therapy in suspected staphylococcal sepse, but is important to considering the sensibility, specificity and validation of the available kits.