title: Correlation of ciprofloxacin resistance with the AdeABC efflux system in Acinetobacter baumannii clinical isolates.
abstract: BACKGROUND
  Acinetobacter baumannii is one of the most important pathogens capable of colonization in burn patients, leading to drug-resistant wound infections. This study evaluated the distribution of the AdeABC efflux system genes and their relationship to ciprofloxacin resistance in A. baumannii isolates collected from burn patients.
  
  
  METHODS
  A total of 68 A. baumannii clinical strains were isolated from patients hospitalized in Motahari Burns Center in Tehran, Iran. Ciprofloxacin susceptibility was tested by the disk diffusion and agar dilution methods. PCR amplification of the adeRS-adeB drug efflux genes was performed for all resistant and susceptible isolates. To assess the role of the drug efflux pump in ciprofloxacin susceptibility, carbonyl cyanide 3-chlorophenylhydrazone (CCCP) was used as an efflux pump inhibitor (EPI).
  
  
  RESULTS
  Approximately 95.6% of the Acinetobacter isolates were resistant to ciprofloxacin, with minimum inhibitory concentration (MIC) values ranging from 4 to ≥128 µg/mL. The susceptibility of 86.1% of the resistant isolates increased by factors of 2 to 64 in the presence of CCCP. All resistant isolates were positive for the adeRS-adeB genes, and 73.2% of them had mutations in the AdeRS regulatory system.
  
  
  CONCLUSIONS
  The results showed that AdeABC genes are common in A. baumannii, which might be associated with ciprofloxacin non-susceptibility, as indicated by the observed linkage to the presence of the genes essential for the activity of the AdeABC, several single mutations occurring in the adeRS regulatory system, and an increase of ciprofloxacin susceptibility in the presence of a CCCP EPI.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.
authors.forename: Abdollah
authors.initials: A
authors.lastname: Ardebili
authors.affiliation: Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Abdolaziz Rastegar
authors.initials: AR
authors.lastname: Lari
authors.affiliation: Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Malihe
authors.initials: M
authors.lastname: Talebi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000151:Acinetobacter Infections / Q000175:diagnosis / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002939:Ciprofloxacin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009154:Mutation; D016133:Polymerase Chain Reaction
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006835:Hydrazones; C070053:carbonyl 3-chlorophenylhydrazone; D002939:Ciprofloxacin
keywords: Acinetobacter baumannii; Burns; Ciprofloxacin; Efflux pump genes; Resistance