Assessment of antibiotic resistance pattern in Acinetobacter baumannii carrying bla oxA type genes isolated from hospitalized patients

Abstract Background & Objective: Acinetobacter baumannii is a Gram-negative coccobacillus and one of the most opportunistic pathogens responsible for serious infections in hospitalized patients. Materials and Methods: During a 12 months study, 221 clinical isolates and 22 environmental Acinetobacter baumannii isolates were collected. In vitro susceptibility of Acinetobacter baumannii isolates to 13 antimicrobial agents: amikacin; cefepime; ceftazidime; ciprofloxacin; meropenem; piperacillin/tazobactam; sulfamethoxazole/ trimethoprim; imipenem; tigecycline; colistin; gentamycin; ceftriaxone; levofloxacin was performed by the disk diffusion method. Also Minimum Inhibitory Concentration (MICs) of imipenem; levofloxacin and cefepime was performed by the E-test according to Clinical and Laboratory Standards Institute (CLSI) criteria. blaOXA-23, blaOXA- 24, blaOXA-58, blaOXA-51 genes were detected by polymerase chain reaction and sequencing. Results: The result of antimicrobial susceptibility test of clinical isolates by the disk diffusion method revealed that all strains of Acinetobacter baumannii were resistant to piperacillin/tazobactam. The rates of resistance to the majority of antibiotics tested varied between 69% and 100 %, with the exception of tigecycline and colistin. Of 221 isolates tested 99(44.8%) were XDR. All strains carried a blaOXA-51-like gene. blaOXA-23 gene was the most prevalent among blaOXA-types Conclusion: Colistin and tigecycline can be effective drugs for treatment of Acinetobacter baumannii infections. Continuous Surveillance for Acinetobacter baumannii multidrug-resistant strains is necessary to prevent the further spread of resistant isolates.