title: Aspirin increases susceptibility of Helicobacter pylori to metronidazole by augmenting endocellular concentrations of antimicrobials.
abstract: OBJECTIVE
  To investigate the mechanisms of aspirin increasing the susceptibility of Helicobacter pylori (H pylori) to metronidazole.
  
  
  METHODS
  H pylori reference strain 26695 and two metronidazole-resistant isolates of H pylori were included in this study. Strains were incubated in Brucella broth with or without aspirin (1 mmol/L). The rdxA gene of H pylori was amplified by PCR and sequenced. The permeability of H pylori to antimicrobials was determined by analyzing the endocellular radioactivity of the cells after incubated with [7-(3)H]-tetracycline. The outer membrane proteins (OMPs) of H pylori 26695 were depurated and analyzed by SDS-PAGE. The expression of 5 porins (hopA, hopB, hopC, hopD and hopE) and the putative RND efflux system (hefABC) of H pylori were analyzed using real-time quantitative PCR.
  
  
  RESULTS
  The mutations in rdxA gene did not change in metronidazole resistant isolates treated with aspirin. The radioactivity of H pylori increased when treated with aspirin, indicating that aspirin improved the permeability of the outer membrane of H pylori. However, the expression of two OMP bands between 55 kDa and 72 kDa altered in the presence of aspirin. The expression of the mRNA of hopA, hopB, hopC, hopD, hopE and hefA, hefB, hefC of H pylori did not change when treated with aspirin.
  
  
  CONCLUSIONS
  Although aspirin increases the susceptibility of H pylori to metronidazole, it has no effect on the mutations of rdxA gene of H pylori. Aspirin increases endocellular concentrations of antimicrobials probably by altering the OMP expression.
authors.affiliation: Department of Gastroenterology, Peking University First Hospital, Beijing, China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Zhang
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Tian
authors.forename: Wen
authors.initials: W
authors.lastname: Gao
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics; D017931:DNA Primers; D004269:DNA, Bacterial / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D005784:Gene Amplification; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics; D008795:Metronidazole / Q000494:pharmacology*; D009601:Nitroreductases / Q000187:drug effects / Q000235:genetics; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D013752:Tetracycline / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; D008795:Metronidazole; D009601:Nitroreductases; C476646:RdxA protein, Helicobacter pylori; D013752:Tetracycline; D001241:Aspirin