Definition: A genus of nonmotile, nonsporeforming, anaerobic bacteria (family Veillonellaceae) containing small (0.3–0.5 mcm in diameter), gram-negative cocci which occur as diplococci short chains and in masses. Carbon dioxide is required for growth, and carbohydrates are not fermented. These organisms are parasitic in the mouth and the intestinal and respiratory tracts of humans and other animals; they produce serologically specific endotoxins (lipopolysaccharides) that induce pyrogenicity and the Schwartzman phenomenon in rabbits; in humans, they have been associated with human bite infections and as a component of polymicrobial abscesses. The type species is Veillonella parvula.
[Adrien Veillon, French bacteriologist, 1864–1931]