Helicobacter pylori and Gastroduodenal Disease.

Abstract

Helicobacter pylori is a gram negative spiral bacterium, which is colonized in human gastric mucosa. This organism was first reported in Australia, 1983. Now H. pylori has been recognized to cause chronic active gastritis, and is a major factor in the pathogenesis of duodenal ulcer and gastric ulcer. It was also reported that its infection is a risk factor for both MALT (mucosa associated lymphoid tissue) lymphoma and gastric adenocarcinoma. H. pylori has many virulence factors. Urease is one of the most important colonization and virulence factors studied. Ammonia made by urease protects the organisms from gastric low pH, and is toxigenic to gastric epithelial cells. Vacuolating toxin and CagA proteins are thought to be pathogenic agents especially for causing gastric and duodenal ulcers. Neutrophil reactions against the bacteria, and the abnormal immunological reactions are also considered to cause the damage of gastric epithelial cells, although the detailed pathogenic mechanisms are still not clear. In developing countries, infection by H. pylori is established in childhood, and the organisms can be identified in the mouth and feces, indicating its infection through water. The infected organisms can be eradicated by administration with proton pump inhibitor and one or two antibiotics. This may provide an useful therapeutic means to the patients especially with recurrent ulceration and MALT lymphoma.