''Fusobacterium nucleatum'' is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

bacterium Bacteria (; : 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 the ...

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit f ...

to the human

oral cavity A mouth also referred to as the oral is the body orifice through which many animals ingest food and vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also the first part of the alime ...

, 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 c ...

. 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 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 ...

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 (: placentas or placentae) 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 ...

, 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. 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 an infection 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 urina ...

. 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 (anatomy), colon or rectum (parts of the large intestine). Signs and symptoms may include Lower gastrointestinal ...

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

colitis Colitis is swelling or inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and ...

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. Acces ...

and inflammatory-associated intestinal carcinogenesis. This suggests direct and specific carcinogenesis. ''F. nucleatum'' can bind to host tissue

E-cadherin Cadherin-1 or Epithelial cadherin (E-cadherin), is a protein that in humans is encoded by the ''CDH1'' gene (not to be confused with the APC/C activator protein CDH1). Mutations are correlated with Hereditary diffuse gastric cancer, gastric, Here ...

s via a FadA, an outer membrane protein. Additionally, a surface expressed

lectin Lectins are carbohydrate-binding proteins that are highly specific for sugar Moiety (chemistry), groups that are part of other molecules, so cause agglutination (biology), agglutination of particular cells or precipitation of glycoconjugates an ...

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

cytokine Cytokines () are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes ...

s associated with higher rates of

metastasis Metastasis is a pathogenic agent's spreading 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, ...

Natural competence

Type IV pili facilitate

natural competence In microbiology, genetics, cell biology, and molecular biology, competence is the ability of a cell to alter its genetics by taking up extracellular DNA from its environment through a process called transformation. Competence can be differentiat ...

in ''F. nucleatum''. Natural competence involves three principal stages: (1) Uptake of exogenous

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

and transport to the cytoplasm, (2) homologous DNA that has been taken up can integrate into the recipient cell genome by

homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organi ...

, and (3) the integrated exogenous DNA can express

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

functions.

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 Pathogenic bacteria

Preterm births

Colon cancer

Natural competence

See also

References

External links