Gastric bacteria other than Helicobacter pylori.

Since the culture of Helicobacter pylori from the human stomach in 1983 there has been renewed interest in other bacteria that had been observed in animal stomachs as early as late in the nineteenth century. Many of these bacteria have now been isolated and have been shown to belong to the same genus, Helicobacter, which currently contains nine species. Study of the gastric helicobacters is important because it provides relevant information about how bacteria can survive in the gastric environment and induce disease. Bacteria of special importance include "Gastrospirillum hominis," a distinctive tightly spiralled bacterium commonly found in cats and dogs, recently shown to be a helicobacter, and that infects a small proportion of human patients, causing a mild chronic gastritis; Helicobacter felis, a bacterium isolated from cats that has been found to be associated with gastritis in one human patient but easily colonizes small laboratory animals, causing gastritis and thus providing a useful model of the human infection; and Helicobacter mustelae, the natural inhabitant of the ferret gastric mucosa, where it also induces a form of chronic gastritis. The latter bacterium shares important properties with H. pylori, namely an ability to adhere firmly to gastric mucosae and an association with peptic ulceration. Investigation of these non-H. pylori gastric bacteria in natural or experimental hosts provides useful models of H. pylori-associated gastroduodenal disease, makes possible assessment of potential therapeutic regimens, and provides information that may result in the development of novel intervention strategies.