title: The effect of omeprazole dosing on the isolation of Helicobacter pylori from gastric aspirates.
abstract: BACKGROUND
  Animal experiments suggest that omeprazole dosing increases shedding of Helicobacter into the gastric lumen, and hence into gastric juice.
  
  
  OBJECTIVE
  To assess the effect of omeprazole dosing on the yield of H. pylori from gastric aspirates of infected volunteers.
  
  
  METHODS
  Six serial nasogastric aspirates, three before and three during dosing with omeprazole 40 mg b.d., were obtained for culture from 10 H. pylori infected volunteers and one uninfected volunteer. To reduce contamination, samples were diluted 1:10 with Maximum Recovery Diluent (MRD; pH 7.0) or HCl-KCl buffer (pH 2.2) prior to culture on Columbia and Dent's agar.
  
  
  RESULTS
  Undiluted gastric juice cultures were rapidly overgrown by upper respiratory tract flora. HCl-KCl dilution resulted in isolation of H. pylori from 77% of infected subject aspirates before, and 67% of aspirates during dosing with omeprazole. The yields were significantly lower with MRD dilution, 47% and 10%, respectively. Omeprazole dosing significantly decreased the yield after MRD dilution, but not after HCl-KCl dilution.
  
  
  CONCLUSIONS
  Decreasing intragastric acidity, by dosing with omeprazole, decreases the isolation of H. pylori from routinely processed gastric aspirates. In vitro acidification of gastric aspirates, by HCl-KCl dilution, increases the isolation of H. pylori both before and during omeprazole dosing.
authors.affiliation: Department of Medicine, Royal Free and University College Medical School, London, UK.
authors.forename: M P
authors.initials: MP
authors.lastname: Williams
authors.forename: J C
authors.initials: JC
authors.lastname: Sercombe
authors.forename: A J
authors.initials: AJ
authors.lastname: Lawson
authors.forename: E
authors.initials: E
authors.lastname: Slater
authors.forename: R J
authors.initials: RJ
authors.lastname: Owen
authors.forename: R E
authors.initials: RE
authors.lastname: Pounder
mesh_terms: D000328:Adult; D000897:Anti-Ulcer Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001944:Breath Tests; D003470:Culture Media; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005750:Gastric Juice / Q000737:chemistry / Q000382:microbiology*; D016481:Helicobacter Infections / Q000097:blood / Q000188:drug therapy; D016480:Helicobacter pylori / Q000187:drug effects* / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016015:Logistic Models; D008297:Male; D009853:Omeprazole / Q000494:pharmacology* / Q000627:therapeutic use; D014508:Urea
chemical_list: D000897:Anti-Ulcer Agents; D003470:Culture Media; D014508:Urea; D009853:Omeprazole