Resistance to Aminoglycosides among Methicillin Resistant Staphylococcus aureus Strains Isolated from Patients with Urinary Tract Infection in Isfahan, Iran. 2017

Aminoglycoside antibiotics are used to treat many Gram-negative and some Gram-positive infections. Among various bacterial species, resistance to AGs arises through a variety of intrinsic and acquired mechanisms, in which by far the most widespread mechanism of resistance to AGs is the inactivation of these antibiotics by AG-modifying enzymes. In this study, we aimed to determine the resistance to aminoglycosides among methicillin resistant Staphylococcus aureus strains in Isfahan. In this study a total of 286 S. aureus strains were isolated from patients with urinary infections in 2 hospitals in Isfahan during 2017 and identified using specific primers. The resistance of MRSA strains to 16 antibiotics was determined and presence of different SCCmec types and genes encoding resistance to aminoglycosides was detected. A total of 112 (39%) cefoxitin resistant and mecA positive S. aureus strains were identified among isolates. All MRSA strains were susceptible to vancomycin, linezolid and quinupristin/dalfopristin and showed high resistance to penicillin, ciprofloxacin, erythromycin and clindamycin. Moreover, 92, 89, 89, 86, 85 and 63% of strains were resistant to tobramycin, kanamycin, amikacin, neomycin and gentamicin, respectively. Ninety seven percent of strains harbored SCCmec type III and aac(6’)-Ie+aph(2’), ant(4’)-Ia, ant(6)-Ia and aph(3’)-IIIa genes were detected among 63, 60, 56 and 38% of strains, respectively. High prevalence of resistance to aminoglycosides among MRSA strains indicating the inefficiency of these antibiotics for treatment of urinary infections in this study.