Trichosporon
Encyclopedia
Trichosporon is a genus
of anamorphic fungi in the family
Trichosporonaceae. All species
of Trichosporon are yeasts 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
. Trichosporon species can also cause severe opportunistic infections (trichosporonosis
) in immunocompromised individuals.
in 1890, based on yeasts isolated from the hairs of a moustache where they were causing the condition known as "white piedra". Behrend called his new species T. ovoides, but subsequently Pleurococcus beigelii (later recombined as Trichosporon beigelii
) was considered to be an earlier name for the same species and was accepted as the type
of the genus Trichosporon.
Over 100 additional yeast species were referred to Trichosporon by later authors. With the advent of DNA sequencing
, however, it became clear that many of these additional species belonged in other genera. Based on cladistic analysis of DNA sequences, just under 40 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 strain that makes T. beigelii synonymous with Trichosporon 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.
, the hyphal compartments acting as arthroconidia (asexual propagules). No teleomorphic (sexual) states are known.
Species are widespread and have been isolated from a wide range of substrates, including human hair (Trichosporon ovoides), soil (T. guehoae), cabbages (T. brassicae), cheese (T. caseorum), scarab beetles (T. scarabaeorum), parrot droppings (T. coremiiforme), and sea water (T. dermatis).
. Occasionally, particularly in circumstances of high humidity, the fungus can proliferate, causing an unpleasant but harmless hair condition known as white piedra
. 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, T. mucoides, T. asteroides, and T. cutaneum. The obsolete name T. beigelii was formerly applied to all or any of these species.
Much more serious opportunistic infections, collectively called trichosporonosis
, have been reported in immunocompromised individuals. Species said to be agents of trichosporonosis are T. asahii, T. asteroides, T. cutaneum, T.dermatis, T. dohaense, T. inkin, T. loubieri, T. mucoides, and T. ovoides.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of anamorphic fungi in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Trichosporonaceae. All species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of Trichosporon are yeasts with no known teleomorphs (sexual states). Most are typically isolated from soil, but several species occur as a natural part of the skin microbiota
Skin flora
The skin flora are the microorganisms which reside on the skin. Most research has been upon those that reside upon the 2 square metres of human skin. Many of them are bacteria of which there are around 1000 species upon human skin from 19 phyla. The total number of bacteria on an average human has...
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
White piedra is a mycosis of the hair caused by several species of fungi in the genus Trichosporon. It is characterized by soft nodules composed of yeast cells and arthroconidia that encompass hair shafts.-Treatment:...
. Trichosporon species can also cause severe opportunistic infections (trichosporonosis
Trichosporonosis
Trichosporonosis is a systemic disease associated with fungi in the genus Trichosporon.It can appear in patients who are immunosuppressed....
) in immunocompromised individuals.
Taxonomy
The genus was first described by the German dermatologist Gustav BehrendGustav Behrend
Gustav Behrend was a German dermatologist who was a native of Neustettin .In 1870 he received his medical doctorate at the University of Berlin, and during the Franco-Prussian War he served as an assistant at the Reserve Lazareth in Berlin...
in 1890, based on yeasts isolated from the hairs of a moustache where they were causing the condition known as "white piedra". Behrend called his new species T. ovoides, but subsequently Pleurococcus beigelii (later recombined as Trichosporon beigelii
Trichosporon beigelii
Trichosporon beigelii is a species of fungus in the family Trichosporonaceae. It is a yeast that was formerly considered to be the cause of an unpleasant hair condition called white piedra and also the cause of a more serious severe opportunistic infection in immunocompromised individuals...
) was considered to be an earlier name for the same species and was accepted as the type
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Trichosporon.
Over 100 additional yeast species were referred to Trichosporon by later authors. With the advent of DNA sequencing
DNA sequencing
DNA sequencing includes several methods and technologies that are used for determining the order of the nucleotide bases—adenine, guanine, cytosine, and thymine—in a molecule of DNA....
, however, it became clear that many of these additional species belonged in other genera. Based on cladistic analysis of DNA sequences, just under 40 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 strain that makes T. beigelii synonymous with Trichosporon 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 hyphae that disarticulate at the septaSeptum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
, the hyphal compartments acting as arthroconidia (asexual propagules). No teleomorphic (sexual) states are known.
Species are widespread and have been isolated from a wide range of substrates, including human hair (Trichosporon ovoides), soil (T. guehoae), cabbages (T. brassicae), cheese (T. caseorum), scarab beetles (T. scarabaeorum), parrot droppings (T. coremiiforme), and sea water (T. dermatis).
Human pathogens
Several Trichosporon species occur naturally as part of the microbiota of human skinSkin flora
The skin flora are the microorganisms which reside on the skin. Most research has been upon those that reside upon the 2 square metres of human skin. Many of them are bacteria of which there are around 1000 species upon human skin from 19 phyla. The total number of bacteria on an average human has...
. Occasionally, particularly in circumstances of high humidity, the fungus can proliferate, causing an unpleasant but harmless hair condition known as white piedra
White piedra
White piedra is a mycosis of the hair caused by several species of fungi in the genus Trichosporon. It is characterized by soft nodules composed of yeast cells and arthroconidia that encompass hair shafts.-Treatment:...
. 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, T. mucoides, T. asteroides, and T. cutaneum. The obsolete name T. beigelii was formerly applied to all or any of these species.
Much more serious opportunistic infections, collectively called trichosporonosis
Trichosporonosis
Trichosporonosis is a systemic disease associated with fungi in the genus Trichosporon.It can appear in patients who are immunosuppressed....
, have been reported in immunocompromised individuals. Species said to be agents of trichosporonosis are T. asahii, T. asteroides, T. cutaneum, T.dermatis, T. dohaense, T. inkin, T. loubieri, T. mucoides, and T. ovoides.