General Information: Normal oral and gastrointestinal bacterium. This genus contains mostly obligately anaerobic bacilli. Many of the isolates are spindle-shaped, or fusiform. This organism belongs to the normal microflora of the human oral and gastrointestinal tracts. It is a very long and slender spindle-shaped bacillus with sharply pointed ends that is characterized by the ability to invade soft tissues. It acts as a bridge between early and late colonizers of the tooth surface, and exerts synergism with other bacteria in mixed infections. It is most frequently associated with periodontal diseases, as well as with some invasive human infections of the head and neck, chest, lung, liver and abdomen, and some anginas. One of the major amino acid and sugar fermentation pathways in Fusobacterium nucleatum produces butyric and acetic acids.