Prevalence of methicillin-resistant Staphylococcus aureus isolated from Moheb Hospital and Miladphenotypic and molecular methods

S. aureus, the second most common cause of nosocomial infections, is regarded as an important factor in the severe infections of the community. Methicillin-resistant strains of this bacterium involve a major pathogen which can cause disease and mortality in Iran and the world. Its treatment seems to be difficult due to the prevalence of resistance to most commonly-used antibiotics. In fact, methicillin -resistant strains need to be identified precisely and rapidly. Therefore, this study intended to assess the resistance to methicillin via the disk diffusion method and PCR for mecA gene. This study was conducted on 100 strains of Staphylococcus aureus collected from clinical various samples of Moheb and Milad hospitals in Tehran. Sensitivity to antibiotics was determined by the disk diffusion method and gene resistance (mecA) was examined by PCR method. Moreover, specific primers were explored and the results were compared. The prevalence of methicillin-resistant strains by the disk diffusion method was 50% (n=50), whereas 74% (n=74) were determined to have mecA gene via PCR analysis. Out of these 100 samples, 61 samples belonged to Moheb hospital, among which 47.54% (n=29) were observed to be methicillin-resistant by disk diffusion method and 60.65% (n=37) via PCR method. Other 39 samples were obtained from Milad Hospital, of which 84/53% (n=21) demonstrated resistance to methicillin via disk diffusion and 87/94% (n=37) via PCR method. The study findings revealed that due to high prevalence of methicillin resistance, a quick and detailed identification method of MRSA is required. Since disk diffusion method proposes relatively high false-negative results and is observed to have a time-consuming nature, PCR can be taken in to consideration as the best method in order to identify methicillin-resistant strains.