Identification o f Clinical Methicillin and Mupirocin-resistant Staphylococcus aureus by Multiplex-PCR

Infections resulted from multi-resistant Staphylococcus aureus are increasing worldwide. In the present study, a Multiplex -PCR assay for the detection of antibiotic resistance genes among S. aureus clinical isolates and for the concomitant identification of these isolates was described. A total of 127 S. aureus isolates were collected from clinical specimens at three teaching hospitals in Tehran, Iran. Screening for methicillin and mupirocin resistance in staphylococcal isolates was performed by disk diffusion method, according to Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of femB, mecA, and iles-2 genes was investigated by multiplex-PCR. The 62.2% and 7.8% of Staphylococcus isolates were positive for mecA and ileS 2 genes, respectively. The femB fragment was amplified in all S. aureus strains tested. There is a 100% concordance between susceptibility and PCR results for isolates which harbored ileS-2. However, 55.1% of staphylococci were found as MRSA in the phenotypic assay. The PCR assay described in this study was able detect three genes for identification of S. aureus and its methicillin and mupirocin resistant genotypes concomitantly in a single reaction. Hence, this method can be used on regular basis as a valuable diagnostic and surveillance tool in clinical laboratories.