title: Efflux Pump Inhibitor Phenylalanine-Arginine Β-Naphthylamide Effect on the Minimum Inhibitory Concentration of Imipenem in Acinetobacter baumannii Strains Isolated From Hospitalized Patients in Shahid Motahari Burn Hospital, Tehran, Iran.
abstract: BACKGROUND
  Acinetobacter baumannii has emerged as a highly troublesome pathogen and a leading cause of mortality and morbidity among hospitalized burn patients.
  
  
  OBJECTIVE
  The aims of this study were to determine the frequency of the AdeABC genes and the role of the efflux pump (s) in the imipenem resistance of A. baumannii strains isolated from burn patients.
  
  
  METHODS
  This study was conducted on 60 A. baumannii isolates collected from 240 wound samples of burn patients admitted to the Burn Unit of Shahid Motahari Burn hospital, Tehran, Iran. Antibiotic susceptibility tests were performed using the Kirby-Bauer disc diffusion and broth microdilution according to the clinical and laboratory standards institute (CLSI) guidelines. The activity of the efflux pump was evaluated using the efflux pump inhibitor, the phenylalanine-arginine Β-naphthylamide (PAΒN). The AdeABC genes were detected by polymerase chain reaction (PCR) and sequencing.
  
  
  RESULTS
  In this study, 100% of the isolates were resistant to cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, cefepime, piperacillin, meropenem, co-trimoxazole, and piperacillin/tazobactam; 56 (94%) to gentamicin; 50 (81%) to amikacin; 58 (97%) to imipenem; and 45 (76%) to tetracycline. Additionally,all the isolates were susceptible to colistin. The susceptibility of the strains to imipenem was highly increased in the presence of the efflux pump inhibitor such that for 58 (96.6%) of the isolates, the PAΒN reduced the minimum inhibitory concentrations (MIC) by 4- to 64-fold. The adeA and adeB genes were detected in 60 (100%) of the isolates, and the adeC gene was present in 51 (85%).
  
  
  CONCLUSIONS
  The efflux pump may play a role in antibiotic resistance in A. baumannii isolates. The ability of A. baumannii isolates to acquire drug resistance by the efflux pump mechanism is a concern. Thus, new strategies are required in order to eliminate the efflux transport activity from resistant A. baumannii isolates causing nosocomial infections.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Gholami
authors.affiliation: Department of Microbiology, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Hashemi
authors.affiliation: Department of Microbiology, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mojdeh
authors.initials: M
authors.lastname: Hakemi-Vala
authors.affiliation: Department of Microbiology, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Goudarzi
authors.affiliation: Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Masoumeh
authors.initials: M
authors.lastname: Hallajzadeh
keywords: Acinetobacter baumannii; AdeABC; Antibiotic Resistance; Burn; Efflux Pump Inhibitor