Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 4 1-2 2015 03 01 1 7 EN Mojtaba Moosavian Health Research Institute, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of MedicalSciences, Ahvaz, IR Iran. AND Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences Ahvaz, IR Iran. Maryam Torabipour Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences Ahvaz, IR Iran 2016 08 07 2016 08 07 Introduction: One of the most important agents in hospital-acquired infections is Staphylococcus aureus. Treatment of methicillin-resistant S. aureus (MRSA) infections with decreased susceptibility to vancomycin has recently been more difficult. The aim of this study was to evaluate the possible presence of vancomycin intermediate S. aureus (VISA) and vancomycin- resistant S. aureus (VRSA) and also to determine the frequency of MRSA in clinical specimens. Methods: In this study, 195 S. aureus isolates were collected from the patients were examined. All of the isolates were identified using standard biochemical tests. Susceptibility of S. aureus isolates against 10 antibiotics was detected by disk diffusion method and was followed by E-test and vancomycin screen agar methods. Minimum inhibitory concentration (MIC) of vancomycin was determined according to the CLSI guidelines. Also, detection of mecA gene was performed by PCR and finally, the results were compared. Results: All of the isolates were susceptible to vancomycin (i.e. MIC range of vancomycin was between 0.25-2 µg/ml). Out of 195 S. aureus isolates, 99 isolates (50.8%) were resistant to methicillin, and mecA gene was detected in 96 isolates. These results also showed that the highest and lowest resistance rate of isolates was to penicillin (96.9%) and chloramphenicol (0%), respectively. Conclusion: Our findings showed that vancomycin can still be used as a valuable drug for treatment of S. aureus infections in our region. However, periodic evaluation of vancomycin MIC of S. aureus isolates is critical for monitoring MRSA and preventing the spread of VISA or VRSA among patients. https://jmb.tums.ac.ir/index.php/jmb/article/view/168 https://jmb.tums.ac.ir/index.php/jmb/article/download/168/114