Distribution and Expression of Efflux Pump Gene and Antibiotic Resistance in Acinetobacter baumannii

Background: Multidrug efflux pump is a ubiquitous mechanism of drug resistance in bacterial pathogens, such as Acinetobacter baumannii, which is mediated by integral membrane transport proteins. The purpose of the current study was to analyse the distribution of adeG and its role in resistance to ciprofloxacin in A. baumannii isolates from two hospitals of Tehran. Methods: Fifty-one isolates of A. baumannii were recovered from Shahid Motahari and Milad hospitals of Tehran, from July 2016 to March 2017. Identification of A. baumannii was confirmed by phenotypically and molecular methods. Antibiotic susceptibility testing was prepared by the Kirby-Bauer method. Resistance to ciprofloxacin was confirmed by determination of minimum inhibitory concentration (MIC). Efflux pumps inhibitor was used for phenotypic detection of active efflux pumps. Real-time polymerase chain reaction (PCR) was used to analyze adeG gene over expression. Results: Fifty-one isolates of A. baumannii were confirmed by phonotypical and molecular methods. Results of antibiotic susceptibility testing confirmed resistance to ciprofloxacin in all isolates. Results of conventional PCR showed that all of the isolates had the adeG gene. The MIC of ciprofloxacin was decreased by 4 to 32 folds or more in 88% of resistant isolates after adding the efflux pump inhibitor. Over expression of AdeG efflux pump gene was confirmed by real-time PCR in 34 strains. Conclusions: In conclusion, multidrug-resistant A. baumannii were prevalent in the studied isolates. Carbonyl cyanide3-chlorophenylhydrazone could reverse the susceptibility to ciprofloxacin in A. baumannii and was associated with overexpression of the adeG gene.