Prevalence of the blaCTX-M and antibiotic resistance pattern among clinical isolates of Acinetobacter baumannii isolated from Zahedan, Southeast Iran

Background: Acinetobacter baumannii is a common opportunistic pathogen that causes major nosocomial infections. This study aimed at determining the antimicrobial resistance pattern and the prevalence of bla(CTX-M) among A. baumannii isolated from the different wards of a teaching hospital in Zahedan, in southeast Iran. Materials and methods: In this cross-sectional study, 141 A. baumannii isolates were identified and confirmed using standard microbial tests from January to September 2018. The susceptibility profile was performed by disk diffusion and broth microdilution methods. The bla(CTX-M) (CTX-M groups 1, 2, 8, 9, and 25) genes were also identified using polymerase chain reaction (PCR). Results: The results showed a high prevalence of antimicrobial resistance in A. baumannii isolates. More than 95% of the isolates were resistant to piperacillin-tazobactam, ceftizoxime, cefotaxime, ceftazidime, imipenem, aztreonam, and cefazolin. Among 141 A. baumannii isolates, 97.2% and 41.1% of the isolates were multidrugresistant (MDR) and extensively drug-resistant (XDR) isolates, respectively. The results also indicated that 61.3% of the isolates were positive for bla(CTX-M) genes with the rate of 22%, 22.7%, 15.6%, and 11.3% for CTX-M-1, 2, 8 and 9, respectively. None of the isolates carried bla(CTX-M-25). Conclusion: The present study showed a high prevalence of bla(CTX-M) genes and MDR strains among A. baumannii isolates. Moreover, the high level of resistance to antibiotics related to the bla(CTX-M) genes can be a risk factor and emphasizes the need for rapid identification of ESBL-producing strains and antimicrobial susceptibility testing for selecting suitable antimicrobial therapy and preventing further spread of their encoding genes.