Genotypic and Phenotypic Characteristics of Efflux Pumps in Acinetobacter spp. Isolated from Inpatients

Background and Acinetobacter spp. is a non-fermentative gram- negative bacterium involving in various nosocomial infections. During last decade increasing number of multidrug-resistant isolates of Acinetobacter spp. have been reported. This type of resistance is possibly related to efflux pumps. This research aimed at identifying the phonotypic and genotypic characteristics of efflux pump in resistance to antibiotics in Acinetobacter spp. isolated from hospitalized patients in Kermanshah, 2013. In this descriptive-analytical study, 100 Acinetobacter spp strains were isolated from different clinical samples including blood, wound, and liquid specimens of hospitalized patients in Imam Reza and Taleghani hospitals in Kermanshah. All isolates were identified by standard biochemical tests. The antimicrobial susceptibility patterns were determined by disk diffusion according to CLSI (Clinical and Laboratory Standards Institute) guidelines in presence and absence of CCCP (carbonyl cyanide m-chlorophenylhydrazone) as an efflux pump inhibitor. PCR was used to detect the adeABC efflux pump genes. The rate of resistant to imipenem was 58%, ampicillin 63%, ceftazidime 94%, erythromycin 55%, clarithromycin 36%, azithromycin 29%, gentamicin 83%, tobramycin 54%, and tetracycline 50%. Highest and lowest levels of resistance were observed for ceftazidime and azithromycin, respectively. Among the Acinetobacter spp. 68% were positive for adeA gene, 88% for adeB gene, and 86% for adeC gene. Frequency of resistance using efflux pump inhibitor was found to be higher in adeA, adeB, and adeC positive Acinetobacter spp. isolates. The highest rate of resistance by efflux pump was observed in ceftazidime (13%) and tetracycline (12%).