Campylobacter concisus is a Gram-negative, highly fastidious, mesophilic bacterium that grows under both anaerobic and microaerobic conditions with the presence of hydrogen significantly aiding growth. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Although the human oral cavity is the natural colonization site of the bacterium, C. concisus may also colonize the intestinal tract of some individuals. In particular, several studies have reported higher intestinal prevalence of C. concisus in patients with IBD compared to healthy controls, which has led to current speculation of the bacterium's implication in the induction of Crohn's disease.