Molecular investigation of methicillin-resistant Staphylococcus epidermidis and Staphylococcus saprophyticus isolated in Shahrekord training hospitals

Coagulase-negative Staphylococci is one of the most important factors for nosocomial infections. Resistance to methicillin has been observed in this group of bacteria. This study was aimed to investigate and compare resistance to methicillin using two phenotypic and genotypic methods in Staphylococcus epidermidis and Staphylococcus saprophyticus bacteria isolated from samples in training hospitals of Shahrekord. In this analytic descriptive study, 2900 various samples including blood, urine, and etc. were collected from patients hospitalized in Hajar (PBUH) and Ayatollah Kashani hospitals of Shahrekord. Then, 150 isolates of coagulase-negative Staphylococci were selected using microbiological experiments. In the next step, phenotypic resistance was simultaneously assessed by disk diffusion and genotypic resistance [methicillin-resistant gene (mecA)] by multiplex PCR. Of isolated 150 cases under study, findings showed that 46.66% of the samples (70 isolates with confidence interval of 95% equal to 38.49-54.98%) were resistant to methicillin in phenotypic analysis. Besides, in genotypic analysis 42.66% of the samples (64 isolates with confidence interval of 95% equal to 34.63-51%) had methicillin-resistant gene (mecA). Distribution of phenotypic and genotypic resistance in two hospitals under study was equal, and had no significant difference (P>0.05). The genotypic results indicate the presence of methicillin-resistance gene. Genotyping through PCR is a reliable tool to show the rate of methicillin-resistance in Staphylococcus epidermidis and Staphylococcus saprophyticus.