title: Effect of biofilm formation by clinical isolates ofHelicobacter pylorion the efflux-mediated resistance to commonly used antibiotics.
abstract: OBJECTIVE
  To evaluate the role of biofilm formation on the resistance ofHelicobacter pylori(H. pylori) to commonly prescribed antibiotics, the expression rates of resistance genes in biofilm-forming and planktonic cells were compared.
  
  
  METHODS
  A collection of 33H. pyloriisolates from children and adult patients with chronic infection were taken for the present study. The isolates were screened for biofilm formation ability, as well as for polymerase chain reaction (PCR) reaction withHP1165andhp1165efflux pump genes. Susceptibilities of the selected strains to antibiotic and differences between susceptibilities of planktonic and biofilm-forming cell populations were determined. Quantitative real-time PCR (qPCR) analysis was performed using16S rRNAgene as aH. pylori-specific primer, and two efflux pumps-specific primers,hp1165andhefA.
  
  
  RESULTS
  The strains were resistant to amoxicillin, metronidazole, and erythromycin, except for one strain, but they were all susceptible to tetracycline. Minimum bactericidal concentrations of antibiotics in the biofilm-forming cells were significantly higher than those of planktonic cells. qPCR demonstrated that the expression of efflux pump genes was significantly higher in the biofilm-forming cells as compared to the planktonic ones.
  
  
  CONCLUSIONS
  The present work demonstrated an association betweenH. pyloribiofilm formation and decreased susceptibility to all the antibiotics tested. This decreased susceptibility to antibiotics was associated with enhanced functional activity of two efflux pumps:hp1165andhefA.
authors.affiliation: Bahareh Attaran, Tahereh Falsafi, Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran 1993893973, Iran.
authors.forename: Bahareh
authors.initials: B
authors.lastname: Attaran
authors.affiliation: Bahareh Attaran, Tahereh Falsafi, Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran 1993893973, Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Falsafi
authors.affiliation: Bahareh Attaran, Tahereh Falsafi, Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran 1993893973, Iran.
authors.forename: Nassim
authors.initials: N
authors.lastname: Ghorbanmehr
mesh_terms: D000328:Adult; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002648:Child; D017291:Clarithromycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D005798:Genes, Bacterial; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S; D008795:Metronidazole; D004917:Erythromycin; D000658:Amoxicillin; D013752:Tetracycline; D017291:Clarithromycin
keywords: Antibiotic resistance; Biofilm; Efflux genes; Helicobacter pylori; hefA; hp1165