الگوي مقاومت آنتي بيوتيكي سويه هاي استافيلوكوكوس اپيدرميديس مقاوم به متي سيلين جدا شده از نمونه هاي باليني در تهران

Antibiotic Resistance Pattern of Mthicillin Resistant Staphylococcus epidermidis Isolated from Clinical Samples in Tehran

Abstract Background and objective: Staphylococcus epidermidis, the most frequently isolated species of coagulase-negative staphylococci (CONS), is the leading cause of infections related to implanted medical devices and became a serious problem in antimicrobial chemotherapy. The aim of the study was to detect and analyze the antibiotic resistance pattern among methicillin resistant S. epidermidis isolated from two hospitals in Tehran in 2012-2013. Materials and methods: Totally 193 isolates of S. epidermidis from clinical samples were collected from two hospitals in Tehran. All isolates were identified at the species level using standard biochemical tests. Susceptibility to eighteen antibiotics was determined using disc diffusion method. MIC of oxacillin and vancomycin in MRSA isolates was also done using Etest according to CLSI recommendation. PCR was used to detect mecA gene. Results: the frequency of oxacillin resistance was 37.3%. The highest level of resistance was observed to penicillin, erythromycin, ciprofloxacin, clindamycin, kanamycin, tobramycin, amikacin and tetracycline respectively. MIC results showed that 42% of isolates showed high level resistant to oxacillin (MIC?128 µg/ml). None of the MRSA isolates were resistant to vancomycin, linezolid and synercid. One hundred percent of the isolates contained mecA gene. Conclusion: This study showed that the prevalence of methicillin resistant S. epidermidis isolates was lower than the other studies in Iran. Synercid, linezolid and vancomycin are the most effective antibiotics against MRSA infections. High resistance of methicillin resistant strains to 1st and second line of antibiotics could be an urgent for public health