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

Acinetobacter baumannii is a Gram-negative coccobacillus and one of the most opportunistic pathogens responsible for serious infections in hospitalized patients. 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. The result of antimicrobial susceptibility test of clinical isolates by the disk diffusion method revealedthat 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 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.