''Fusobacterium nucleatum'' is a

Gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure wate ...

negative, anaerobic oral

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, commensal to the human

oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

, that plays a role in

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main caus ...

. This organism is commonly recovered from different monocultured microbial and mixed infections in humans and animals. In health and disease, it is a key component of periodontal

plaque Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate or tablet fixed to a wall to mark an event, person, etc. * Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I * Pla ...

due to its abundance and its ability to coaggregate with other bacteria species in the oral cavity.

Preterm births

Research implicates periodontal disease caused by ''F. nucleatum'' with

preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 we ...

s in humans. In many studies, ''F. nucleatum'' cells have been isolated from the

amniotic fluid The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products betwee ...

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mater ...

, and chorioamnionic membranes of women delivering prematurely. Moreover, laboratory mice inoculated (directly into the blood) with ''F. nucleatum'' have been found to deliver prematurely, and the pathology of the infection seems to mirror observations in humans. Together, this research provides evidence for a possible causal connection between ''F. nucleatum''-caused periodontal disease and at least some cases of preterm delivery. ''F. nucleatum'' can also be isolated from the vaginal microbiome, especially in women with a condition known as

bacterial vaginosis Bacterial vaginosis (BV) is a disease of the vagina caused by excessive growth of bacteria. Common symptoms include increased vaginal discharge that often smells like fish. The discharge is usually white or gray in color. Burning with urination ...

. Both ''F. nucleatum'' vaginal colonization and bacterial vaginosis also have been linked with preterm birth and infections within the uterus. Thus, preterm birth arising by infections caused by ''F. nucleatum'' could also arise from invasive infection into the uterine tissue originating from the colonized vagina.

Colon cancer

''F. nucleatum'' has a demonstrated association with

colorectal cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel m ...

. ''Fusobacterium'' species have been found at higher quantities in certain types of colon tumors than in surrounding colon tissue or the colons of healthy individuals, but whether this is an indirect correlation or a causal link is unclear. A distinguishing mechanism has been described by which ''F. nucleatum'' creates a pro-inflammatory environment which is conducive to

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

growth through the recruitment of tumor-infiltrating

immune cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

, which, unlike other bacteria linked to colorectal carcinoma, does not exacerbate other pathological processes such as

colitis Colitis is swelling or inflammation of the large intestine ( colon). Colitis may be acute and self-limited or long-term. It broadly fits into the category of digestive diseases. In a medical context, the label ''colitis'' (without qualification) ...

enteritis Enteritis is inflammation of the small intestine. It is most commonly caused by food or drink contaminated with pathogenic microbes,Dugdale, David C., IIII, and George F Longretc"Enteritis" MedlinePlus Medical Encyclopedia, 18 October 2008. Access ...

and inflammatory-associated intestinal carcinogenesis. This suggests direct and specific carcinogenesis. ''F. nucleatum'' can bind to host tissue E-cadherins via a FadA, an outer membrane protein. Additionally, a surface expressed

lectin Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in rec ...

called Fap2 mediates ''F. nucleatum'' adherence to colorectal cancer cells that express Gal/GalNAc moieties on their surface. Binding via Fap2 has also been shown to up-regulate production of

cytokines Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

associated with higher rates of

metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...

References

External links

Type strain of ''Fusobacterium nucleatum'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q5510311 Gram-negative bacteria Bacterial vaginosis Bacteria described in 1922 Fusobacteriota

Preterm births

Colon cancer

See also

References

External links