molecular epidemiology of aminoglycosides resistance in acinetobacter spp. with emergence of multidrug-resistant strains

background: acinetobacter spp. is characterized as an important nosocomial pathogen and increasing antimicrobial resis­tance. our aim was to evaluate antimicrobial susceptibility and aminoglycosides resistance genes of acinetobacter spp. iso­lated from hospitalized patients. methods: sixty isolates were identified as acinetobacter species. the isolates were tested for antibiotic resistance by disc diffu­sion method for 12 antimicrobials. the presence of apha6, aacc1 aada1, and aadb genes were detected using pcr. results: from the isolated acinetobacter spp. the highest resistance rate showed against amikacin, tobramycin, and cef­tazidim, respectively; while isolated bacteria were more sensitive to ampicillic/subactam. more than 66% of the isolates were resistant to at least three classes of antibiotics, and 27.5% of mdr strains were resistant to all seven tested classes of antim­icrobials. the higher mdr rate presented in bacteria isolated from the icu and blood samples. more than 60% of the mdr bacteria were resistance to amikacin, ceftazidim, ciprofloxacin, piperacillin/tazobactam, doxycycline, tobramycin and levofloxacin. also, more than 60% of the isolates contained phosphotransferase apha6, and acetyltransferase genes aacc1, but adenylyltransferase genes aada1 (41.7%) , and aadb (3.3%) were less prominent. 21.7% of the strains contain three aminogly­coside resistance genes ( apha6 , aacc1 and aada1) . conclusion: the rising trend of resistance to aminoglycosides poses an alarming threat to treatment of such infections. the find­ings showed that clinical isolates of acinetobacter spp. in our hospital carrying various kinds of aminoglycoside resis­tance genes.