[The use of oxacillin and cefoxitin disk-diffusion method and PCR for the identification methicillin-resistant Staphylococcus epidermidis].

Methicillin-resistant S. epidermidis are recognized as one of the most important nosocomial infections. Because of the different expression level of mecA gene which is under regulatory genes control, detection of methicillin resistance by phenotypic methods may leads to false negative or false positive results. The aim of this study was to estimate effectiveness of MRSE strains identification using oxacillin (1 microg) and cefoxitin (30 microg) disk-diffusion method in comparison with PCR, considered as a "gold standard". The analysis of 120 strains isolated from clinical materials of patients of the University Hospital at the L. Rydygier Collegium Medicum in Bydgoszcz, University of Nicolaus Copernicus in Toruń indicated high degree of correlation between phenotypic methods with taken disks. Results consistency of detecting methicillin resistance between oxacillin disk diffusion method and PCR concerned 95% strains. In case of cefoxitin 4,2% S. epidermidis strains detected phenotypically as MSSE were mecA-positive. Our results show that disk-diffusion method with disks mentioned above is characterized by comparable specificity and sensitivity amounted 90,8% and 100% for oxacillin and 92,3% and 100% for cefoxitin respectively.