Background and purpose: Methicillin-resistant Staphylococcus. aureus (MRSA) is specific strain of S.aureus that is a major cause of nosocomial infection. Nowadays, Vancomycin is the first-line treatment of severe MRSA infections. However, resistance to Vancomycin is reported in the form of Vancomycin-resistant Staphylococcus aureus (VRSA) too. This study aimed at determining the prevalence of MRSA and VRSA in healthcare staff and inpatients.

Materials and methods: The study was performed in 447 healthcare workers and inpatients in Teaching Hospitals, in Sari, Iran, 2015. Staphylococcus aureus were isolated from the subjects using diagnostic tests. Then antibiotic resistance patterns of the isolates was determined by disk diffusion method. E-TEST was used for the methicillin and Vancomycin resistant isolates. Prevalence of mecA resistant gene in the isolates was analyzed by PCR. Finally, Induced resistance to Clindamycin was investigated.

Results: E-TEST showed that 31.31% of the isolates were resistant to methicillin and 16.1% were vancomycin-intermediate S. aureus (VISA). Prevalence of mecA gene in resistant isolates was 96.8%. The highest resistance was detected against Gentamicin (45.5%) and the lowest resistance rates were found against Vancomycin (0%) and Amikacin (14.1%). We also found that 12.9% of MRSA isolates were inducible resistance to Clindamycin.

Conclusion: This study revealed that MRSA isolates have a high resistance to Erythromycin, Clindamycin, Gentamicin, and Ciprofloxacin. Also, a high rate of multidrug-resistant was seen in MRSA isolates. But despite intermediate resistance to Vancomycin, this antibiotic can be used as a valuable drug in treatment of MRSA.