Fusobacterium nucleatum is a Gram-negative, anaerobic bacterium, commensal to the human oral cavity, that plays a role in periodontal disease.

In health and disease, it is a key component of periodontal plaque due to its abundance and its ability to coaggregate with other bacteria species in the oral cavity.

In many studies, F. nucleatum cells have been isolated from the amniotic fluid, placenta, and chorioamnionic membranes of women delivering prematurely.

Moreover, laboratory mice intravenously inoculated with F. nucleatum have been found to deliver prematurely, and the pathology of the infection seems to mirror observations in humans.

A distinguishing mechanism has been described by which F. nucleatum creates a pro-inflammatory environment which is conducive to tumor growth through the recruitment of tumor-infiltrating immune cells, which, unlike other bacteria linked to colorectal carcinoma, does not exacerbate other pathological processes such as colitis, enteritis and inflammatory-associated intestinal carcinogenesis.