Detection of methicillin-resistance gene in Staphylococcus epidermidis strains isolated from patients in Al-Zahra Hospital using polymerase chain reaction and minimum inhibitory concentration methods

Background: In recent years, antibiotic resistance of Staphylococcus epidermidis to methicillin has significantly increased, making it essential to study resistance to methicillin, which is a determining factor in the appropriate treatment pattern. The purpose of this study was to identify methicillin-resistant genes in S. epidermidis strains using polymerase chain reaction (PCR) and to determine their mean minimum inhibitory concentration (MIC) to methicillin using E-test method. Materials and Methods: MIC was determined on 146 samples of S. epidermidis using E-test method. Moreover, all samples were tested for the presence of mecA gene using PCR. Results: PCR test showed 75.34% of the samples to contain mecA gene. Methicillin resistance test was performed using E-test on all the samples, which showed resistance in different dilutions. Conclusion: The frequency of mecA gene in S. epidermidis isolates was 75.34%. Among the various applied tests used for determining methicillin resistance, sensitivity and specificity of PCR were the highest and reached 100%. Sensitivity and specificity were found to be 95.3% and 94.7%, respectively, for phenotypic test (E-test) and 86.5% and 80.9%, respectively, for disk diffusion method. Based on the above results, it seems that resistance of S. epidermidis to methicillin is on the rise, and therefore more research is warranted.