This genus contains strictly anaerobic, Gram-non-sporing rods which are often large; some are spindle-shaped but many are not. They differ biochemically from the Bacteroides group, although they are considerable biochemical differences between reference strains of fusobacteria. Many of the fusobacteria produce irregular rhizoid colonies on blood agar; they do not produce black or brown pigment.
Fusobacteria are potential pathogens of man and animals. These organisms are well-recognized commensals of the human mouth and are associated with periodontal infections and pleura-pulmonary sepsis, but they can be involved in infection elsewhere in the body. For example, fusobacteria necrophorum has been encountered in a wide range of human infections including pelvic and abdominal sepsis and septicaemic conditions.