DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
RG-1 organism.
Cryptococcus laurentii (Kufferath) Skinner
Culture: Colonies (SDA) are cream-coloured, often becoming a deeper orange-yellow
with age, with a smooth mucoid texture.
Microscopy: Spherical and elongated budding yeast-like cells or blastoconidia, 2.0-
5.5 x 3.0-7.0 μm. No pseudohyphae present.
India Ink Preparation: Positive - narrow but distinct capsules are present.
Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow
Germ Tube - L-Sorbose v L-Arabinose + D-Glucitol +
Fermentation Sucrose + D-Arabinose + α-M-D-glucoside +
Glucose - Maltose + D-Ribose + D-Gluconate +
Galactose - Cellobiose + L-Rhamnose + DL-Lactate v
Sucrose - Trehalose + D-Glucosamine - myo-Inositol +
Maltose - Lactose + N-A-D-glucosamine - 2-K-D-gluconate +
Lactose - Melibiose + Glycerol v D-Glucuronate +
Trehalose - Raffinose + Erythritol v Nitrate -
Assimilation Melezitose + Ribitol + Urease +
Glucose + Soluble Starch v Galactitol + 0.1% Cycloheximide -
Galactose v D-Xylose + D-Mannitol + Growth at 37 O C -,w
Note: Some strains of C. laurentii may develop brown pigment on bird seed agar and
turn CGB media blue, similar to C. gattii, however C. laurentii assimilates both lactose
and melibiose while C. gattii does not. Along with C. albidus, C. laurentii accounts for
80% of the non-neoformans/gattii infections. Impaired cellular immunity is the most
common risk factor with HIV infection and low CD4 counts a common comorbidity.
Invasive devices are an additional risk factor.
Antifungal Susceptibility: C. laurentii (Australian National data); MIC µg/mL.
Note: All Cryptococcus species are intrinsically resistant to echinocandins.
No. 64
AmB 7 1 2 3 1
FLU 6 1 1 3 1
VORI 6 2 2 1 1
POSA 5 1 1 2 1
ITRA 7 1 2 2 1 1
5FC 7 7