[Role of Helicobacter pylori infection in gastric metaplasia in the duodenum in the production of duodenal ulcer].

Helicobacter pylori (H. pylori) is frequently detected in not only the antrum but also the gastric juice and the duodenum with gastric metaplasia, which is believed to be a response of duodenal mucosa to injury by hyperacidity, in most of duodenal ulcer patients. Conversely, the normal duodenum is not infected with H. pylori in non-duodenal ulcer patients, even if H. pylori is present in the antrum and/or the gastric juice. All patients with H. pylori in the duodenum has the H. pylori infection in the gastric antrum. Patients with H. pylori in the gastric juice also has H. pylori infection in the antrum. These findings may support the following hypothesis in the formation of duodenal ulcer. A high duodenal acid load leads to the formation of gastric metaplasia in the duodenal bulb, where can be easily infected by gastric H. pylori through the gastric juice. As a result of the duodenal colonization of H. pylori, the duodenal mucosa impaired by ammonia of H. pylori could has the formation of duodenal ulcer.