Other helicobacters involved in human diseases

Spiral, motile bacteria have evolved to inhabit the mucus of the intestinal crypts. The best known of these spiral, microaerobic organisms is Campylobacter jejuni. We now recognize that the intestinal crypts of a variety of animals, as well as humans are also the natural reser- voir of many members of the genus Helicobacter. Indeed, H. cinaedi and H. fennelliae, previously classi- fied as camyplobacters, were first isolated from inflamed tissues of homosexual males suffering from procitits and colitis (1). Other recently named helicobacters, H. pul- lorum, H. canis, H. canadensis and 'H. rappini' have been isolated from the diarrheic feces of humans (2,3,4, 5). With the exception of H. canadensis, these helico- bacters also have been isolated from the feces of animals with and without diarrhea (3). Rodent helicobacters, H. hepaticus and H. bilis have been linked to both chronic hepatic and intestinal disease and are increas- ingly being used in mouse models to understand the pathogenesis of helicobacter induced gastrointestinal disease (6,7,8). Of the gastric helicobacters, H. pylori, is the best known and the most important in terms of global impact on human disease. However, two other gastric helicobacters, H. heilmannii and H. felis are associated with gastric disease in humans and are wor- thy of discussion (9,10). Today at least 23 formally named helicobacters have been identified and an addi- tional 35 or more novel helicobacters are awaiting for- mal naming. The purpose of this review will be to high- light the expanding role that other helicobacters, though not as well known as H. pylori, play in gastrointestinal disease in humans.