Campylobacter and helicobacter in the etiology of gastrointestinal diseases

The order Campylobacterales comprises two genera: Campylobacter and Helicobacter, with a widespread distribution in both humans and animals. They are Gram-negative, spiral, helical and microaerophilic bacteria, with an optimal growth temperature of 37°C for H. pylori and 42°C for C. jejuni strains. While Helicobacter pylori are restricted to humans, other helicobacter species can be found in different mammals and occasionally in humans. Several Campylobacter species are recognized as human pathogens, while distinct species are pathogenic only occasionally, in children, the elderly and immunocompromised patients. Campylobacters and helicobacters are well adapted to the living conditions inside the gastrointestinal tract, where they can cause diseases as a consequence of inflammation. In addition, they are related to certain extraintestinal diseases, post-infectious sequels, malignancy and autoimmunity. Different clinical presentations of human disorders may be the consequences of the diversity in host immune response, bacterial genome, endotoxin activity as well as specific bacterial virulence factors