title: Effects of acid suppression and bismuth medications on the performance of diagnostic tests for Helicobacter pylori infection.
abstract: OBJECTIVE
  This study was designed to investigate whether acid suppression and bismuth medications interfere with the performance of diagnostic tests for Helicobacter pylori (H. pylori) infection.
  
  
  METHODS
  Sixty patients with previous diagnoses of atrophic gastritis and H. pylori infection made in gastric biopsies taken at Hospital Departmental, Pasto, Colombia, were enrolled in the study. 13C breath urea test (UBT) and stool antigen test (HpSA) were performed simultaneously. Two baseline tests were performed: one 7 days before and another the day before starting medications. A total of 20 patients received for 2 wk one of the following treatments: a) ranitidine; b) lansoprazole; or c) bismuth subsalicylate. The tests were repeated while the patients were on the prescribed medication on days 7 and 14 and then 2 wk after finishing the medication.
  
  
  CONCLUSIONS
  Utilizing standard cut-off values for the tests, our results indicate that in the case of the 13C UBT test, ranitidine does not interfere with the results, whereas lansoprazole and bismuth may be expected to yield a significant proportion of false negative results (30-40% for lansoprazole and 45-55% for bismuth). In the case of the HpSA test, ranitidine does not interfere, whereas lansoprazole and bismuth may be expected to yield a nonsignificant proportion of false negative results (15-25% for lansoprazole and 10-15% for bismuth). Absolute values for both tests may be used to study the effects of the pharmacological agents on the characteristics of the infection.
authors.affiliation: Department of Pathology, Universidad del Valle, Cali, Colombia.
authors.forename: L E
authors.initials: LE
authors.lastname: Bravo
authors.forename: J L
authors.initials: JL
authors.lastname: Realpe
authors.forename: C
authors.initials: C
authors.lastname: Campo
authors.forename: R
authors.initials: R
authors.lastname: Mera
authors.forename: P
authors.initials: P
authors.lastname: Correa
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000897:Anti-Ulcer Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000942:Antigens, Bacterial / Q000032:analysis; D001729:Bismuth / Q000494:pharmacology / Q000627:therapeutic use*; D001944:Breath Tests; D005243:Feces / Q000737:chemistry; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D064747:Lansoprazole; D009853:Omeprazole / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D009942:Organometallic Compounds / Q000494:pharmacology / Q000627:therapeutic use*; D011899:Ranitidine / Q000494:pharmacology / Q000627:therapeutic use*; D012459:Salicylates / Q000494:pharmacology / Q000627:therapeutic use*; D012680:Sensitivity and Specificity; D014508:Urea / Q000378:metabolism
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000897:Anti-Ulcer Agents; D000942:Antigens, Bacterial; D009942:Organometallic Compounds; D012459:Salicylates; D064747:Lansoprazole; C015715:bismuth subsalicylate; D011899:Ranitidine; D014508:Urea; D009853:Omeprazole; D001729:Bismuth