Trichosporon: Introduction,pathogenecity, lab diagnosis and treatment

Introduction of Trichosporon

The fungus Trichosporon (genus) is characterized by the development of structures like hyaline, septate hyphae that fragment into oval or rectangular arthroconidia. The colony characteristics are suggestive for the usually raised colony and have a waxy appearance, which develops radial furrows and irregular folds.

Pathogenicity of Trichosporon

6 species of medical importance are listed below-

Trichosporon asahii
Trichosporon asteroides
Trichosporon cutaneum
Trichosporon inkin
T. mucoides and
T. ovoides.

They are a minor component of normal skin flora and are widely distributed in nature. They are regularly associated with the soft nodules of white piedra and have been involved in a variety of opportunistic infections in an immunosuppressed patients.

Disseminated infections are most frequently caused by T. asahii and have been associated with the following conditions like leukemia,

organ transplantation

multiple myeloma

aplastic anemia

lymphoma

solid tumors and

AIDS.

Disseminated infections are often fulminated and widespread, with lesions occurring in the liver, spleen, lung, and gastrointestinal tract.

Infections in non-immunosuppressed patients include endophthalmitis after surgical extraction of cataracts, endocarditis usually following insertions of prosthetic cardiac valves, peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD), and intravenous drug abuse.

Risk group

They come under risk group-2 organisms.

Laboratory diagnosis of Trichosporon

Potassium hydroxide (KOH) preparation
Culture of the specimen into Sabouraud dextrose agar (SDA) or Potato dextrose agar (PDA)
Lactophenol cotton blue (LPCB) tease mount
Assimilations tests using a variety of sugars like glucose, galactose, sucrose, maltose, cellobiose, trehalose, and so on

Key to medically important species

Arthroconidia barrel-shaped; thallus, not meristematic –T. asahii

Arthroconidia elongate, or thallus meristematic –T. asteroides

Not tolerant to cycloheximide – T. cutaneum

Growth with Myo-inositol, no growth with L-arabinose – T. inkin

Tolerant to cycloheximide –T. mucoides

Appressoria present in slide culture – T. ovoides

Treatment

Following anti-fungal drugs use for treatment these etiological agents and they are-

Fluconazole
Itraconazole
Posaconazole
Voriconazole
Amphotericin B
Flucytosine
Caspofungin
Anidulafungin

but anti-fungal susceptibility may vary between species and resistant strains have been reported. Therefore, antifungal susceptibility testing of individual strains is recommended.

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