Abstract

The incidence of methicillin resistance has risen among nosocomial isolates ofStaphylococcus aureus and coagulase negative staphylococci. The present study was carried out to investigate the prevalence of methicillin-resistant Staphylococcus aureus(MRSA) and methicillin-resistant coagulase negative staphylococci (MRCoNS) and to determine their antibiotic susceptibility pattern. A total of one hundred and thirty clinical staphylococcal isolates recovered from blood, tracheal aspirate, urine and wound specimens were evaluated for susceptibility to penicillin, amikacin, ciprofloxacin, vancomycin, erythromycin, ceftriaxone, methicillin, rifampin and gentamicin by Disk diffusion method and molecular detection of mecA gene. The results showed that MRCoNS were more resistant to these antibiotics as compared to MRSA and the most effective antibiotic to use for staphylocoocal isolates is vancomycin showing (100% of S. aureus and 90% of CoNS) efficacy. The mecA gene was detected in 56% of the isolatedS. aureus and 70% of the CONS isolates. The prevalence of methicillin resistant staphylococci in Iran was very high and 45.4% of MRSA and MRCoNS isolates were at least resistance to 3 or more classes of antibiotics. The high prevalence of MRSA immerged in Iran could be originated due to antibiotic pressure and poor control measures on the application of antibiotics such as methicillin.

Key words: Staphylococcus aureus (S. aureus), coagulase-negative staphylococci (CoNS), mecA gene, methicillin-resistance