EFFECT OF PROTON PUMP INHIBITORS ON THE DETECTION OF HELICOBACTER-PYLORI IN GASTRIC BIOPSIES

Background: Proton pump inhibitors are known to decrease the activity of Helicobacter pylori organisms within the stomach and to shift their distribution proximally. This effect may reduce the sensitivity of hi stological examination and rapid urease testing for H. pylori on biops ies taken from recommended sites. It is of particular relevance if a p roton pump inhibitor has been prescribed before the patient has underg one diagnostic endoscopy. Methods: We studied patients referred to our open-access upper gastrointestinal endoscopy service who had either b een on no medication (controls) or were already taking proton pump inh ibitors. Biopsies taken from the gastric antrum and corpus were used f or rapid urease testing and for histological examination. Sera, taken from patients who had no evidence of H. pylori in biopsies, were teste d for IgG H. pylori antibodies as an alternative indicator of infectio n. Results: H. pylori organisms were detected by histological examinat ion in 27 of 40 controls (68%) and in 13 of 25 patients taking proton pump inhibitors (52%). Among patients with positive histology (organis ms detected in either antral or corpus biopsies, or both), only the se nsitivity of the antral urease test read at 1 h was significantly lowe r in patients taking proton pump inhibitors than in controls, with no significant difference in sensitivities of the antral urease test at 2 4 h, of the corpus urease test at 1 or 24 h, or of histology from the antrum or corpus. Of patients with negative histology, none of 13 cont rols compared with six of 12 patients taking proton pump inhibitors (5 0%) had positive serology (P = 0.005). Five (83%) of the six histology -negative, seropositive patients taking proton pump inhibitors had his tological changes consistent with H. pylori gastritis even though no o rganisms were detected. Conclusions: Treatment with a proton pump inhi bitor before endoscopy reduces the sensitivity of antral and corpus bi opsies for H. pylori detection, both by urease testing and histologica l examination. If proton pump inhibitors already prescribed cannot be discontinued for an adequate period before endoscopy, patients should have biopsies taken from the corpus as well as from the antrum, and se rum should be tested for H. pylori.