title: Role of efflux pump inhibitor in decreasing antibiotic cross-resistance of Pseudomonas aeruginosa in a burn hospital in Iran.
abstract: BACKGROUND
  Multidrug resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression. This study phenotypically examined the role of efflux pump inhibitors in decreasing antibiotic cross-resistance between beta-lactams, fluoroquinolones, and aminoglycosides in P. aeruginosa isolates from burn patients in Iran.
  
  
  METHODS
  A total of 91 phenotypically and genotypically confirmed P. aeruginosa samples were studied. Multidrug cross-resistance was determined using the disk diffusion method and minimum inhibitory concentration (MIC) test. The contribution of efflux pumps was determined by investigating MIC reduction assay to markers of beta-lactams, fluoroquinolones, and aminoglycosides in the absence and presence of an efflux pump inhibitor. All the isolates were also tested by polymerase chain reaction for the presence of mexA, mexC, and mexE efflux genes.
  
  
  RESULTS
  Of the isolates, 81 (89%) and 83 (91.2%) were multidrug resistant according to the disk diffusion and MIC method, respectively. Cross-resistance was observed in 67 (73.6%) and 68 (74.7%) of isolates according to the disk diffusion and MIC method, respectively. In the presence of the efflux pump inhibitor, twofold or higher MIC reduction to imipenem, cefepime, ciprofloxacin, and gentamicin was observed in 59, 65, 55, and 60 isolates, respectively. Except for two isolates that were negative for mexC, all isolates were positive for mexA, mexC, and mexE genes simultaneously.
  
  
  CONCLUSIONS
  Efflux pumps could cause different levels of resistance based on their expression in clinical isolates. Early detection of different efflux pumps in P. aeruginosa could allow the use of other antibiotics and efflux pump inhibitors in combination with antibiotic therapy.
authors.affiliation: Rasool-Akram hospital, Iran University of Medical Sciences, Tehran, Iran. m.talebitaher2000@yahoo.com.
authors.forename: Mahshid
authors.initials: M
authors.lastname: Talebi-Taher
authors.forename: َAli
authors.initials: َ
authors.lastname: Majidpour
authors.forename: Abbas
authors.initials: A
authors.lastname: Gholami
authors.forename: Samira
authors.initials: S
authors.lastname: Rasouli-Kouhi
authors.forename: Maryam
authors.initials: M
authors.lastname: Adabi
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001693:Biological Transport, Active / Q000187:drug effects*; D002056:Burns / Q000150:complications*; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D024841:Fluoroquinolones / Q000494:pharmacology; D005798:Genes, Bacterial; D006761:Hospitals; D006801:Humans; D007492:Iran; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D047090:beta-Lactams