DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 69
Cryptococcus gattii (Vanbreus. & Takashio) Kwon-Chung & Boekhout
Culture: Colonies (SDA) cream-coloured smooth, mucoid, yeast-like colonies.
Microscopy: Globose to ovoid budding yeast-like cells 3.0-7.0 x 3.3- 7.9 µm.
India Ink Preparation: Positive - distinct, wide gelatinous capsules are present. Some
strains may not produce apparent capsules from culture.
Dalmau Plate Culture: Budding yeast cells only. No pseudohyphae present.
Bird Seed Agar: Colonies turn dark brown in colour as colonies selectively absorb a
brown pigment from this media. Colonies are often more mucoid when compared with
C. neoformans (Staib, 1987).
Canavanine Glycine Bromothymol Blue (CGB) Agar: Turns blue within 2-5 days.
Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, nd No Data
Germ Tube - L-Sorbose - L-Arabinose +,w D-Glucitol +
Fermentation Sucrose + D-Arabinose + M-D-glucoside +
Glucose - Maltose + D-Ribose v D-Gluconate +
Galactose - Cellobiose +,w L-Rhamnose + DL-Lactate -
Sucrose - Trehalose + D-Glucosamine v myo-Inositol +
Maltose - Lactose - N-A-D-glucosamine v 2-K-D-gluconate nd
Lactose - Melibiose - Glycerol - D-Glucuronate nd
Trehalose - Raffinose +,w Erythritol - Nitrate -
Assimilation Melezitose + Ribitol v Urease +
Glucose + Soluble Starch + Galactitol + 0.1% Cycloheximide -
Galactose + D-Xylose + D-Mannitol + Growth at 37 O C +
Key Features: Encapsulated yeast; absence of pseudohyphae; growth at 37 O C;
positive hydrolysis of urea; negative fermentation of sugars and positive assimilation
of glucose, maltose, sucrose, galactose, trehalose, raffinose, inositol, cellobiose,
rhamnose, arabinose, melezitose and xylose, and negative assimilation of nitrate,
lactose, melibiose, erythritol and soluble starch; growth on bird seed (Guizotia
abyssinica seed) or caffeic acid agar - colonies turn a dark brown colour; growth on
CGB agar turning it blue within 2-5 days.
Antifungal Susceptibility: C. gattii (Australian National data); MIC µg/mL.
Note: All Cryptococcus species are intrinsically resistant to echinocandins.
No. 64
AmB 152 1 3 18 52 55 12 10 1
FLU 152 2 13 29 48 38 19 2 1
VORI 130 5 12 32 44 20 13 4
POSA 90 2 9 12 23 26 16 1 1
ITRA 152 7 22 38 61 23 1
5FC 152 2 10 38 52 39 7 4