title: Negative Effect of Proton-pump Inhibitors (PPIs) on Helicobacter pylori Growth, Morphology, and Urease Test and Recovery after PPI Removal--An In vitro Study.
abstract: BACKGROUND
  Proton-pump inhibitor (PPI) consumption does lead to false-negative results of Helicobacter pylori diagnostic tests such as biopsy culture and rapid urease test (RUT).
  
  
  METHODS
  Helicobacter pylori isolates from 112 dyspeptic patients with (56.5%) or without (43.5%) PPI consumption were recruited for examining the negative effects of omeprazole (OMP), lansoprazole (LPZ), and pantoprazole (PAN) on H. pylori viability, morphology, and urease, in vitro. The effect of a sublethal concentration of OMP on bacterial features and their recovery after removal of OMP was also assessed.
  
  
  RESULTS
  Of 112 culture-positive gastric biopsies, 87.5% were RUT positive and 12.5% RUT negative. There was a significant correlation between negative RUT results and PPI consumption (p < .05). OMP (minimum inhibitory concentration, MIC 32 μg/mL) and LPZ (MIC 8 μg/mL) inhibited the growth of 78.6% of H. pylori isolates. OMP and LPZ inhibited urease of 90.3% of isolates between 0 and 40 minutes and 54.4% between 20 and 40 minutes, respectively. PAN did not inhibit H. pylori growth and urease. Three 3-day (9 days) consecutive subcultures of H. pylori on brucella blood agar (BBA) supplemented with OMP resulted in reduced bacterial viability (1+), compared with control (4+), change of spiral morphology to coccoid, and reduction in pink color intensity in urea agar. Bacterial growth (1+), morphology, and urease test did not improve after the first 3-day and second 3-day (6 days) subcultures on BBA. However, relative recovery occurred after the third 3-day (9 days) subculture and complete recovery was observed after the fourth 3-day (12 days) subculture, as confluent growth (4+), 100% spiral cells, and strong urease test.
  
  
  CONCLUSIONS
  Proton-pump Inhibitors exert transient negative effects on H. pylori viability, morphology, and urease test. Accordingly, cessation of PPI consumption at least 12 days before endoscopy could help avoiding false-negative results of H. pylori diagnostic tests.
authors.affiliation: Department of Microbiology, School of Biology, University College of Sciences, University of Tehran, 14176-14411, Tehran, Iran.
authors.forename: Parastoo
authors.initials: P
authors.lastname: Saniee
authors.affiliation: Department of Microbiology, School of Biology, University College of Sciences, University of Tehran, 14176-14411, Tehran, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Shahreza
authors.affiliation: Department of Microbiology, School of Biology, University College of Sciences, University of Tehran, 14176-14411, Tehran, Iran.
authors.forename: Farideh
authors.initials: F
authors.lastname: Siavoshi
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000494:pharmacology; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D005260:Female; D016480:Helicobacter pylori / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology* / Q000502:physiology; D006801:Humans; D064747:Lansoprazole / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008875:Middle Aged; D009853:Omeprazole / Q000494:pharmacology; D000077402:Pantoprazole; D054328:Proton Pump Inhibitors / Q000494:pharmacology*; D014510:Urease / Q000032:analysis*; D055815:Young Adult
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000900:Anti-Bacterial Agents; D054328:Proton Pump Inhibitors; D064747:Lansoprazole; D000077402:Pantoprazole; D014510:Urease; D009853:Omeprazole
keywords: Helicobacter pylori; PPIs; growth; morphology; negative effect; urease