Helicobacter /hel′ikōbak′tər/ [Gk, helix, coil + bakterion, small staff] , a genus of gram-negative, rod-shaped, microaerophilic bacteria of the family Spirillaceae, consisting of motile, spiral organisms with multiple sheathed flagella; formerly classified in the genus Campylobacter. The bacteria are found in the gastric mucosal layer; many people are infected without showing any symptoms. H. pylori is the causative agent of stomach ulcers, gastritis, and duodenitis. It causes 90% of duodenal ulcers and 80% of gastric ulcers. Infection significantly increases the risk of developing gastric cancer or mucosal-associated-lymphoid type lymphoma. Antibiotics can eliminate infection and ulcer.
