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The reduction of gastric acidity by antacids, 1-3 H2 receptor antagonists, 1 4 5 and omeprazole -a substituted benzimidazole that is a potent proton pump inhibitor 6-8 -has been reported to increase gastric bacterial colonisation. Decreased gastric acidity due to atrophic gastritis is a common cause of reduced gastric secretion, resulting in overgrowth of gastric flora. 9 10 Omeprazole potently inhibits gastric acid secretion by altering the activity of H + /K+ adenosine triphosphatase 7 and reduces intragastric acidity more effectively than H2 receptor antagonists. 11 This decrease in gastric acid secretion with omeprazole is long lasting. 12-14 Thus, omeprazole may also increase bacterial colonisation in the jejunum, by altering jejunal pH due to gastric hypochlorhydria. The clinical consequences of omeprazole induced bacterial overgrowth in the jejunum are not however clear.
We formulated the following hypothesis: increased bile acid deconjugation in the jejunum of patients receiving omeprazole occurs due to bacterial overgrowth in the jejunum, induced by gastric hypochlorhydria.
To test this hypothesis, we determined whether: (1) patients with gastric ulcer and healthy volunteers who have received omeprazole exhibit positive bile acid breath tests due to bacterial overgrowth in the jejunum; (2) the bacteria in the jejunum are capable of deconjugation; (3) the deconjugation of glycine-1- 14 C labelled glycocholate is related to the change in gastric pH induced by omeprazole; and (4) subjects with a positive bile acid breath test exhibit fat malabsorption.
Materials and methods
Breath tests and bacterial studies were performed in 21 patients with gastric ulcer and 19 healthy volunteers at the First Department of Internal Medicine, Yokohama City University School of Medicine. The study was approved by the Ethical Committee of Yokohama City University School of Medicine. Written informed consent was obtained from each subject.
STUDY SUBJECTS
The study involved 21 male patients with gastric ulcer (group 1) and 19 healthy male volunteers (group 2) who were treated with oral omeprazole 20 mg daily before breakfast for five weeks. The healthy volunteers (aged 24-75 years) were not taking other medication at the time of the study. The patients (aged 27-71 years) were allowed (but not encouraged) to take antacids in addition to omeprazole. Patients with benign gastric ulcer at the time of routine endoscopy were included;...