title: Aspirin inhibits the growth of Helicobacter pylori and enhances its susceptibility to antimicrobial agents.
abstract: OBJECTIVE
  The role of Helicobacter pylori and aspirin in peptic ulcer formation and recurrence remains an important clinical topic. The interaction between aspirin and H pylori in vitro is also not clear. We investigated the effect of aspirin on the growth of H pylori and on the susceptibility of H pylori to antimicrobials.
  
  
  METHODS
  Time killing studies of H pylori were performed with different concentrations of aspirin and salicylate. Growth of bacteria was assessed spectrophotometrically and by viable colony count. The effects of aspirin on the efficiency of colony formation and on metronidazole induced mutation to rifampicin resistance in H pylori were determined. Minimal inhibitory concentrations (MICs) of aspirin and metronidazole were tested by the standard agar dilution method. MICs of amoxycillin and clarithromycin were determined by the E test method.
  
  
  RESULTS
  Aspirin and salicylate inhibited the growth of H pylori in a dose dependent manner and bactericidal activity was due to cell lysis. Aspirin 400 micro g/ml caused a 2 logs decrease in colony forming units/ml at 48 hours, and suppressed the normal ability of metronidazole to induce new mutations to rifampicin. The IC(90) of aspirin was 512 micro g/ml. Increased susceptibility of amoxycillin, clarithromycin, and metronidazole to H pylori was observed at 1 mM (180 micro g/ml) aspirin.
  
  
  CONCLUSIONS
  Aspirin inhibited the growth of H pylori, suppressed the mutagenic effect of metronidazole, and enhanced the susceptibility of H pylori to antimicrobial agents. This mechanism is important in future drug development for effective clearing and overcoming resistance.
authors.affiliation: Department of Gastroenterology, First Hospital, Peking University, Beijing, China. bcywong@hku.hk
authors.forename: W H
authors.initials: WH
authors.lastname: Wang
authors.forename: W M
authors.initials: WM
authors.lastname: Wong
authors.forename: D
authors.initials: D
authors.lastname: Dailidiene
authors.forename: D E
authors.initials: DE
authors.lastname: Berg
authors.forename: Q
authors.initials: Q
authors.lastname: Gu
authors.forename: K C
authors.initials: KC
authors.lastname: Lai
authors.forename: S K
authors.initials: SK
authors.lastname: Lam
authors.forename: B C Y
authors.initials: BC
authors.lastname: Wong
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D017291:Clarithromycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D016480:Helicobacter pylori / Q000187:drug effects* / Q000254:growth & development; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D012459:Salicylates / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D012459:Salicylates; D008795:Metronidazole; D000658:Amoxicillin; D017291:Clarithromycin; D001241:Aspirin