Changes in the intragastric distribution of Helicobacter pylori during treatment with omeprazole.

Omeprazole is a powerful inhibitor of gastric acid and may suppress Helicobacter pylori by effecting the pKa of H pylori urease, by altering the pattern of infection, or by promoting overgrowth of other bacteria. At routine endoscopy H pylori was detected by histology and culture before and after four weeks' treatment with omeprazole, 40 mg each morning. A 13C-urea breath test was also done at t = 0, 2, 4, and 6 weeks. Thirty nine patients with duodenal ulcer (n = 25) or reflux oesophagitis (n = 14) were studied, of whom 29 of 39 had H pylori infection. During omeprazole treatment, 13C-urea breath test values fell significantly--mean (SEM) values before treatment and at four weeks were 23.0 (2.1) and 15.5 (2.7) per mil respectively, p < 0.001. Before treatment H pylori was seen in 28 of 29 antral, 29 of 29 corpus, and 28 of 29 fundic biopsy specimens. After four weeks of omeprazole treatment, the histological density of H pylori in the antrum and corpus was reduced (p < 0.001), while that in the fundus was increased. The migration of H pylori from the antrum to the fundus was associated with a corresponding decrease in the activity of antral gastritis. H pylori was not seen in antral biopsy specimens from 12 of 29 patients whose median excess delta 13CO2 excretion fell from 23.0 to 9.9 per mil. In the body mucosa, 26 of 29 specimens were still positive for H pylori and there was no significant change in the gastritis type. Two weeks after finishing treatment, the mean (SEM) excess delta 13CO2 excretion returned to levels before treatment. Omeprazole decreases antral H pylori colonisation but increases that in the fundus. The changes in the intragastric distribution of the organism are associated with concomitant changes in the activity of gastritis and are matched by a progressive fall in the excretion of delta 13CO2.