Detección fenotípica y molecular de resistencia a meticilina en S. aureus

detecting methicillin resistance is complicated due to the heterogeneity of its phenotypic expression, making its detection difficult in the laboratory; this has led to the development of several techniques to increase its expression in vitro. four techniques for detecting methicillin resistance were evaluated: the disk diffusion method with oxacillin (ox, 1 μg) and cephoxitin (fox, 30 μg); the screening test, minimum inhibitory concentration (mic) and detection of pbp2a, using the presence of meca gen as a reference method; 286 strains of s. aureus, were processed. the sensibility (sen), specificity (spe), positive predictive value (ppv), negative predictive value (npv) and efficiency (efc) of each method were determined. a total of 50 oxacillin resistant, pbp2a positive (meca positive) strains were obtained. sensibility of the ox disk was 99.14%; and of the fox disk was 100%. the sen, ppv, nvp and efc of the other methods were 100%. all the tests, except the ox disk diffusion method (99.14% of esp), were 100% specific.