Helicobacter pylori and the pathogenesis of gastroduodenal inflammation.

Helicobacter pylori is a newly discovered gram-negative bacterium that lives in the human stomach and duodenum. Infection with this organism is strongly associated with type B antral gastritis and with peptic ulcer disease. Recent evidence from human volunteer studies, therapeutic trials with antimicrobial agents, and experiments with animal models indicates that H. pylori plays an etiologic role in the pathogenesis of type B gastritis. Gastric metaplasia is observed in virtually all patients with duodenal ulceration and may be the target tissue for these bacteria in the duodenum. Patients in whom H. pylori can no longer be identified after ulcer therapy remain in remission for significantly longer than do patients in whom the organism can be found. The data concerning an etiologic role of H. pylori in duodenal ulcer are suggestive but not yet conclusive. Present antimicrobial therapy can suppress but usually cannot eliminate H. pylori.