Pattern of resistance to different antibiotic groups among clinical isolates of Acinetobacter baumannii in two hospitals in Tehran

The global increase in resistance to antibiotics among clinical isolates of Acinetobacter baumannii is reported from several countries, but its true prevalence in Iran is less known. The objective of this study was determination of the frequency of resistance to different antibiotics among Acinetobacter baumannii isolated from patients in two hospitals in Tehran, Iran, in 2013, to help selection of antibiotics in empirical therapy of infection with these isolates. Disk diffusion method according to recommendation of CLSI was used for determination of resistance to 18 antibiotics from 8 different groups (aminoglycosides, carbapenems, cephalosporins, penicillins/ß-lactamase inhibitors, antipseudomonal penicillins/ß-lactamase inhibitors, fluoroquinolones, folate pathway inhibitors and tetracyclines) in 106 Acinetobacter baumannii clinical isolates. Frequency of resistance to antibiotics among Acinetobacter baumannii isolates were as follows: cefotaxime 99%, ciprofloxacin, ceftriaxone, cefepime, ceftazidime, ticarcillin-clavulanic acid, meropenem and trimethoprim-sulphamethoxazole 98.1%, tetracycline 97.4%, levofloxacin and piperacillin-tazobactam 97.2%, amikacin, imipenem 97.1%, gentamicin 89.6%, ampicillin-sulbactam 83%, tobramycin 77.4%, doxycycline 60.4% and minocycline 50.9%. All Acinetobacter baumannii clinical isolates have shown multidrug resistance (resistance to at least one agent in ≥3 antimicrobial group) and some of resistance patterns were more commonly seen. The high frequency of antibiotic resistance in clinical isolates of Acinetobacter baumannii in Iran as shown in this study makes epidemiological surveillance of susceptibility of these bacteria more essential.