Physiology and biochemistry of Helicobacter pylori.

Since Helicobacter pylori was first isolated in 1982, a tremendous amount of work has been carried out on the pathogenic effects of the organism and latterly on its physiology, nutrition and biochemistry. It is a microaerophilic Gram-negative bacillus that is catalase- and oxidase-positive and expresses superoxide dismutase. High levels of urease are produced, the activity of which can be used in the identification of the organism and the infected state. Other noted features include the production of a cytotoxin and an associated protein (CagA). The bacterium is the major aetiological agent in the development of chronic active gastritis, gastric and duodenal ulcers, gastric adenocarcinomas and mucosa-associated lymphoid tissue lymphoma of the stomach. To gain a more complete understanding of how H. pylori causes disease a detailed knowledge of its biochemistry, physiology and nutrition is required.