Overview: Bacteria of genus Campylobacter make up approximately 1 to 3% of the microbiota at most sites within the mouth. There are seven named and one unnamed species recognized in the HOMD.

Ecological role/importance in health and disease: Unlike many members of the oral microbiome, Campylobacter species are motile by means of flagella. C. gracilis is detected primarily in dental plaque, while C. concisus and C. rectus are more broadly distributed in the mouth. Three species, C. gracilis, C. rectus, and C. showae, are considered part of the "orange complex" in subgingival plaque marking part of the ecological succession from health toward periodontitis (Socransky et al. 1998). Some species of Campylobacter cause infections known as campylobacterosis, but these species are not members of the oral microbiome.