Characterization of integrons and associated gene cassettes in Acinetobacter baumannii strains isolated from intensive care unit in Tehran, Iran

Objective: To determine the antimicrobial susceptibility patterns, the frequency of\udintegrons and associated gene cassettes in Acinetobacter baumannii (A. baumannii)\udstrains isolated from selected hospital intensive care units.\udMethods: During a ten-month period, 120 A. baumannii isolates were studied. The\udresistance rates to different classes of antimicrobial agents were determined. PCR was\udused to detect different types of integrons and associated gene cassettes.\udResults: The resistance rates to the majority of antibiotics tested were found to be between 39.3% and 99.1%. No isolate was observed to be resistant to colistin and polymyxin B. The rate of extensive drug-resistance among these clinical isolates was 62.5%.\udThe prevalence of class 1 and 2 integrons was found to be 74.1% and 12.5%, respectively. Seven different gene cassettes (ampC, aacA4-catB8, ISAba1-blaOXA-23-GES-14,\udaadA2-cm1A6-GES-14-qacF, VIM-25-GES-24-qacF, dfrA5-ISAba1-blaOXA-51-blaOXA-40\udand aadA2-GES-11-IMP-1) were observed in Class 1 integron-carrying strains. Three\udgene cassettes (IMP-4, VIM-2-VEB-aacA4 and dfrA2-sat-2-aadA4) were detected in class\ud2 integron-bearing A. baumannii strains.\udConclusions: A high prevalence of integron was described among multidrug resistant\udA. baumannii in the hospital. The findings highlighted the need for continuous surveillance in\udorder to prevent dissemination of multidrug resistance among A. baumannii strains in Iran