Evaluate the Prevalence of aac(6')-Ie-aph (2′′)-Ia Gene among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus Isolates from the Hospital Mashhad

Methicillin-resistant Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. The purpose of this study was to evaluate the prevalence of aac(6')-Ie-aph(2′′)-Ia gene among clinical isolates of methicillin-resistant Staphylococcus aureus isolated from Mashhad hospitals.
This study was cross-sectional and descriptive-analytic (from September 2013 to July 2014 performed on clinical samples of Ghaem, Pasteur, Imam Hadi, Imam Reza hospitals in Mashhad). After collecting 45 clinical isolates of MRSA antimicrobial, sensitivity pattern of isolates was determined by disk diffusion method using disks of oxacillin, gentamicin, tubramycin, amikacin, and kanamycin according to the CLSI guidelines. PCR method was used for detection and determination of prevalence of mecA antimicrobial-resistance gene (used to confirm the diagnosis of MRSA) and aac(6')-Ie-aph(2′′)-Ia genes. Data collected after the entry into SPSS version 18 using chi-square test.
In this study, 45 cases of Methicillin-resistant Staphylococcus aureus were evaluated. %51 of cases was isolated from ulcers; while %37, %7 and %5 were respectively isolated from blood, urine and sputum. According to the antibiotic sensitivity test results, Staphylococcus aureus isolates were resistant against kanamycin (%80), tobramycin (%71), amikacin (%53) and gentamicin (%31). The aac(6')-Ie-aph(2′′)-Ia gene at %44/24 of isolates of methicillin-resistant Staphylococcus aureus was detected.
Compared to others, this study shows lower rate of antimicrobial resistance which could be due to lower frequency of resistance mechanisms (Aminoglycoside-resistance genes, efflux pomps, …) in these isolates. The discrepancy between results could also point to diversity in aminoglycoside-resistance in different geographical regions.