Molecular Epidemiology of Aminoglycosides Resistance in Acinetobacter Spp. with Emergence of Multidrug-Resistant Strains

Abstract

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.