Prevalence of Antibiotic Resistance in Methicillin-resistant Staphylococcus aureus and Determining Aminoglycoside Resistance Gene by PCR in Sari and Tehran Hospitals

Background and Staphylococcus aureus is one of the major causes of community and hospital-acquired infections. Aminoglycosides are potent bactericidal agents that are often used in combination with beta-lactam or glycopeptide in treatment of staphylococcal infections. The aim of this study was to investigate the prevalence of the aminoglycoside modifying enzyme aac(6΄)-Ie/aph(2”) genes and mecA. In current study, 174 clinical isolates of MRSA from different clinical specimens were tested for antibiotic susceptibility using the Kirby Bauer method. MRSA isolates were detected by disc diffusion method using 1 ug oxacillin and 30 ug cefoxitin discs. Then, MRSA strains were further analyzed for detection of mecA and aminoglycoside resistant aac (6΄)-Ie/aph (2˝) genes by PCR. All strains were resistant to oxacillin and cefoxitin. The highest and lowest resistances were found against erythromycin (85.1%) and trimethoprim/sulfamethoxazole (24.7%), respectively. In PCR, mecA gene was detected in 100% of the strains and 77% of the strains were found to harbor aac(6′)/aph(2//)-Ia gene. According to this study, the prevalence of aminoglycosides resistant genes is increasing in MRSA isolates.