Fusobacteria are commensal organisms in the oral cavity.

Fusobacterium necrophorum, a Gram negative anaerobic bacillus.

F. necrophorum and Fusobacterium nucleatum are the most important among the non-spore forming anaerobic bacilli in causing human infections.

F. necroporum may occasionally cause septicaemia with metastatic abscesses (Lemierre's syndrome).