Trichosporon Cutaneum
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''Trichosporon'' is a
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of anamorphic
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
in the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Trichosporonaceae. All
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of ''Trichosporon'' are
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
s with no known teleomorphs (sexual states). Most are typically isolated from soil, but several species occur as a natural part of the skin microbiota of humans and other animals. Proliferation of ''Trichosporon'' yeasts in the hair can lead to an unpleasant but non-serious condition known as
white piedra White piedra (or tinea blanca) is a mycosis of the hair caused by several species of fungi in the genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant ...
. ''Trichosporon'' species can also cause severe
opportunistic infection An opportunistic infection is an infection that occurs most commonly in individuals with an immunodeficiency disorder and acts more severe on those with a weakened immune system. These types of infections are considered serious and can be caused b ...
s ( trichosporonosis) in
immunocompromised Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affe ...
individuals.


Taxonomy

The genus was first described by the German
dermatologist Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A dermatologist is a specialist medi ...
Gustav Behrend in 1890, based on yeasts isolated from the hairs of a
moustache A moustache (; mustache, ) is a growth of facial hair grown above the upper lip and under the human nose, nose. Moustaches have been worn in various styles throughout history. Etymology The word "moustache" is French language, French, and i ...
where they were causing the condition known as "
white piedra White piedra (or tinea blanca) is a mycosis of the hair caused by several species of fungi in the genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant ...
". Behrend called his new species '' Trichosporon ovoides''. Friedrich Küchenmeister and Rabenhorst had, however, previously described a species in 1867 from the hairs of a wig. They thought that the organism was an
alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...
and placed it in the genus '' Pleurococcus'' as ''Pleurococcus beigelii''. The French mycologist Vuillemin later realized it was a
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
and transferred it to the genus ''Trichosporon'', considering it to be an earlier name for ''Trichosporon ovoides''. Over 100 additional yeast species were referred to ''Trichosporon'' by later authors. With the advent of
DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The ...
, however, it became clear that many of these additional species belonged in other genera. Based on
cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analysis of DNA sequences, 12 species are now accepted in the genus. DNA sequencing has also shown that white piedra can be caused by more than one ''Trichoporon'' species. As a result, ''Trichosporon beigelii'' has become a name of uncertain application. McPartland & Goff selected a
neotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
strain that makes ''T. beigelii'' synonymous with '' Cutaneotrichosporon cutaneum''. Guého and others, however, have argued that ''T. beigelii'' should be discarded (as a dubious name) and Behrend's original ''T. ovoides'' (for which a neotype strain has also been selected) should become the type. As a result of this uncertainty, the name ''T. beigelii'' is now obsolete.


Description and habitat

''Trichosporon'' species are distinguished microscopically by having yeast cells that germinate to produce hyaline
hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...
e that disarticulate at the
septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...
, the hyphal compartments acting as arthroconidia (asexual propagules). No teleomorphic (sexual) states are known. Species of ''Trichosporon'' and related genera are widespread and have been isolated from a wide range of substrates, including human hair (''Trichosporon ovoides''), soil (''Cutaneotrichosporon guehoae''),
cabbage Cabbage, comprising several cultivars of '' Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.& ...
s (''Apiotrichum brassicae''),
cheese Cheese is a type of dairy product produced in a range of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk (usually the milk of cows, buffalo, goats or sheep). During prod ...
(''T. caseorum''), scarab beetles (''Apiotrichum scarabaeorum''),
parrot Parrots (Psittaciformes), also known as psittacines (), are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genus (biology), genera, found mostly in ...
droppings (''T. coremiiforme''), and
sea water Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximate ...
(''Cutaneotrichosporon dermatis'').


Human pathogens

Several ''Trichosporon'' species occur naturally as part of the microbiota of human skin. Occasionally, particularly in circumstances of high humidity, the fungus can proliferate, causing an unpleasant but harmless hair condition known as
white piedra White piedra (or tinea blanca) is a mycosis of the hair caused by several species of fungi in the genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant ...
. Soft, pale nodules containing yeast cells and arthroconidia form on hairs of the scalp and body. The species responsible include ''Trichosporon ovoides'', '' T. inkin'', '' T. asahii'', ''Cutaneotrichosporon mucoides'', ''T. asteroides'', and '' Cutaneotrichosporon cutaneum''. The obsolete name ''T. beigelii'' was formerly applied to all or any of these species. Much more serious
opportunistic infection An opportunistic infection is an infection that occurs most commonly in individuals with an immunodeficiency disorder and acts more severe on those with a weakened immune system. These types of infections are considered serious and can be caused b ...
s, collectively called trichosporonosis, have been reported in
immunocompromised Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affe ...
individuals. Species said to be agents of trichosporonosis are ''T. asahii'', ''T. asteroides'', '' Cutaneotrichosporon cutaneum'', ''Cutaneotrichosporon dermatis'', ''T. dohaense'', ''T. inkin'', ''Apiotrichum loubieri'', ''Cutaneotrichosporon mucoides'', and ''T. ovoides''.


Species

*'' Trichosporon aquatile'' *'' Trichosporon asahii'' *'' Trichosporon asteroides'' *'' Trichosporon caseorum'' *'' Trichosporon coremiiforme'' *'' Trichosporon dohaense'' *'' Trichosporon faecale'' *'' Trichosporon inkin'' *'' Trichosporon insectorum'' *'' Trichosporon japonicum'' *'' Trichosporon lactis'' *'' Trichosporon ovoides''


References


External links

* {{Taxonbar, from=Q3272399 Tremellomycetes Yeasts