BACKGROUND AND OBJECTIVES Staphylococcus aureus is the cause of many local and systemic infections. S. aureus is known as the main nosocomial pathogen due to its ability to generate a wide range of virulence factors. Examining the pattern of bacterial antibiotic resistance is important to prevent the spread of resistant strains in society. Investigating the antibiotic resistance pattern of S. aureus isolated from clinical samples was the aim of the current study. MATERIALS AND METHODS Clinical specimens were collected from local medical labs, directly inoculated on mannitol salt agar, and incubated at 37 °C for 24-48 hours. Isolates were identified as S. aureus using colonial morphology, Gram staining, catalase, coagulase and DNase activity tests, and mannitol fermentation test. After identifying the isolated bacteria, phenotypic resistance detection method was used to determine the antibiotic resistance pattern. In addition, oxacillin screening plate method was used for the determination of methicillin resistant isolates. RESULTS AND DISCUSSION The antibiotic susceptibility assay was performed using disc diffusion method. The results revealed that the isolates were resistant to most regular antibiotics, including penicillin (66.6%) and tetracycline (49.9%). In addition, all isolated S. aureus were sensitive to gentamicin (100%). Furthermore, the most intermediate resistance was also observed regarding the vancomycin antibiotic (41.6%). CONCLUSION This study indicated that a high percentage of S. aureus isolates are resistant to common antibiotics such as penicillin, and their intermediate degree of resistance to glycopeptide antibiotics such as vancomycin is increasing. Therefore, it is important to prevent the unrestrained spread of resistant isolates in the community.
