Helicobacter pylori and the evolution of gastritis.

Following the isolation of Helicobacter pylori from the stomachs of patients with peptic ulcer in 1982, intensive research has examined the relationship between this organism and gastritis. H. pylori affects the grade and activity of gastritis, the quality of surface epithelial cells, and the nature of mucus production. Gastritis results from a direct action, involving bacterial cytotoxins and enzymes, and also in an indirect way through the effect of monocyte and granulocyte infiltration. Eradication of H. pylori leads to the long-term healing of gastritis. H. pylori is also associated with intestinal metaplasia and the development of mucosa-associated lymphoid tissue (MALT). Regression of MALT lymphomas has been reported after H. pylori eradication treatment.