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Laboratory Methods

School of Molecular & Biomedical Science
THE UNIVERSITY OF ADELAIDE
AUSTRALIA 5005

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Dr David Ellis

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Trichosporon beigelii

Synonym: Trichosporon cutaneum

On Sabouraud's dextrose agar colonies are white or yellowish to deep cream colored, smooth, wrinkled, velvety and dull in appearance with a mycelial fringe. Microscopic morphology shows abundant pseudohyphae and some true hyphae segmenting into arthroconidia. Numerous spherical to oval budding blastoconidia 3.5-7.0 x 3.5-14.0 um in size are also present.

India Ink Preparation: Negative.

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: True mycelium is abundant; arthroconidia of variable size may be abundant or scarce. Pseudomycelium often occurs with blastoconidia in chains or clusters.

Physiological Tests:

Germ Tube test is Negative
Hydrolysis of Urea is Positive
Growth on Cycloheximide medium is Variable
Growth at 37C is Variable

Fermentation Reactions: Where fermentation means the production of gas and is independent of pH changes.

Negative: Glucose; Sucrose; Lactose; Galactose; Maltose; Trehalose.

Assimilation Tests:

Positive: Glucose; Galactose; Maltose; Sucrose; D-Xylose; Soluble Starch (delayed); Lactose; Cellobiose; D-Ribose {some negative); DL-Lactic acid; DL-Lactic acid (delayed); Salicin (delayed); DL-Lactic acid.
Variable: Trehalose; Melezitose; Glycerol; Succinic acid; Raffinose; Melibiose; Erythritol; Inositol; L-Rhamnose; D-Arabinose; L-Arabinose; Ribitol; L-Sorbose; D-Mannitol; Citric acid.
Negative: Potassium nitrate; Galactitol (some positive).

Clinical significance:

Trichosporon beigelii is a minor component of normal skin flora, and is widely distributed in nature. T. beigelii is regularly associated with the soft nodules of white piedra, and has been involved in a variety of opportunistic infections in the immunosuppressed patient.

Disseminated infections are most frequently associated with leukemia, organ transplantation, multiple myeloma, aplastic anemia, lymphoma, solid tumors and AIDS. Disseminated infections are often fulminate and widespread, with lesions occurring in the liver, spleen, lungs and gastrointestinal tract.

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

Trichosporon beigelii

Synonym: Trichosporon cutaneum

Clinical significance:

Mycosis: Miscellaneous Yeast Infections

Further reading: