Dermatophyte

Dermatophyte (from Greek δέρμα derma "skin" (GEN δέρματος dermatos) and φυτόν phyton "plant")[1] is a common label for a group of fungus of Arthrodermataceae that commonly causes skin disease in animals and humans.[2] Traditionally, these anamorphic (asexual or imperfect fungi) mold genera are: Microsporum, Epidermophyton and Trichophyton.[3] There are about 40 species in these three genera. Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the Ascomycota (see Teleomorph, anamorph and holomorph for more information on this type of fungal life cycle). As of 2019 a total of nine genera are identified and new phylogenetic taxonomy has been proposed.[4]

Dermatophytes cause infections of the skin, hair, and nails, obtaining nutrients from keratinized material.[5] The organisms colonize the keratin tissues causing inflammation as the host responds to metabolic byproducts. Colonies of dermatophytes are usually restricted to the nonliving cornified layer of the epidermis because of their inability to penetrate the viable tissue of an immunocompetent host. Invasion does elicit a host response ranging from mild to severe. Acid proteinases (proteases),[6] elastase, keratinases, and other proteinases reportedly act as virulence factors. Additionally, the products of these degradative enzymes serve as nutrients for the fungi.[6] The development of cell-mediated immunity correlated with delayed hypersensitivity and an inflammatory response is associated with clinical cure, whereas the lack of or defective cell-mediated immunity predisposes the host to chronic or recurrent dermatophyte infection.

Some of these skin infections are known as ringworm or tinea (which is the Latin word for "worm"), though infections are not caused by worms.[3][7] It is thought that the word tinea (worm) is used to describe the snake-like appearance of the dermatophyte on the skin.[7] Toenail and fingernail infections are referred to as onychomycosis. Dermatophytes usually do not invade living tissues, but colonize the outer layer of the skin. Occasionally the organisms do invade subcutaneous tissues, resulting in kerion development.

  1. ^ δέρμα, φυτόν. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  2. ^ "dermatophyte" at Dorland's Medical Dictionary
  3. ^ a b Cite error: The named reference :0 was invoked but never defined (see the help page).
  4. ^ de Hoog GS, Dukik K, Monod M (2016). "Toward a Novel Multilocus Phylogenetic Taxonomy for the Dermatophytes. Mycopathologia. 2017;182(1-2):5-31. doi:10.1007/s11046-016-0073-9". Mycopathologia. 182 (1): 5–31. doi:10.1007/s11046-016-0073-9. PMC 5283515. PMID 27783317.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ Midgley, G; Moore, M. K.; Cook, J. C.; Phan, Q. G. (1994). "Mycology of nail disorders". Journal of the American Academy of Dermatology. 31 (3 Pt 2): S68-74. doi:10.1016/s0190-9622(08)81272-8. PMID 8077512.
  6. ^ a b Goldsmith, Lowell A.; Fitzpatrick, Thomas B. (2012). Fitzpatrick's dermatology in general medicine (8th ed.). New York: McGraw-Hill Medical. ISBN 9780071669047. OCLC 743275888.
  7. ^ a b Jameson, J. Larry; Kasper, Dennis L.; Fauci, Anthony S.; Hauser, Stephen L.; Longo, Dan L.; Loscalzo, Joseph (2018-02-06). Harrison's principles of internal medicine (Twentieth ed.). New York. ISBN 9781259644047. OCLC 990065894.{{cite book}}: CS1 maint: location missing publisher (link)