Antibiotic resistance dependent on efflux pump in the isolates of clinical and environmental Acinetobacter baumannii

Members of Acinetobacter genus are normal flora and the causal agent of the opportunistic nosocomial infections. The aim of this study was to investigate the ability to acquire drug resistance through efflux pump mechanism in multidrug-resistant Acinetobacter spp. and the role of PAβN (Phenyl Arginin β naphtyamid) as an efflux pump inhibitor.    In the cross-sectional descriptive study 83 clinical isolates and 62 environmental isolates were collected. Identification of the isolated bacteria was carried out by standard biochemical experiments and polymerase chain reaction (PCR) using specific primers of 16S rRNA and 16S-23S rRNA. Antibiotic susceptibility tests were conducted through disc diffusion and MIC test based on CLSI guidelines. The activity of the efflux pump was evaluated using the PaβN, and the adeABC gene frequency was assessed by PCR.   Of the total of the samples evaluated, 56 (67.47%) clinical isolates and 34 (54.84%) environmental isolates were identified as Acinetobacter spp. In accordance with the results of the antibiogram test, 100% of the isolates were resistant to cefotaxime and ceftriaxone. Only 7.13% of the clinical isolates and 5.89% of the environmental isolates were not multidrug-resistant (MDR). Prevalence of the adeB was 69.60%, 82.14%, and 76.80% in the clinical isolates and 50%, 85.30%, and 73.50% in the environmental isolates, respectively. Furthermore, tetracycline MIC was decreased in all resistant isolates in the presence of PAβN.   The results showed that the efflux pump could play a role in antibiotic resistance in Acinetobacter spp. isolates. Owing to the resistance of Acinetobacter isolates against cephalosporine, it is suggested to avoid prescribing.