DESCRIPTIONS OF MEDICAL FUNGI

102
Descriptions of Medical Fungi
Geotrichum candidum Link.
Synonymy: Galactomyces candidus de Hoog & M.Th. Smith.
The genus Geotrichum and related species have undergone extensive taxonomic
revision (de Hoog and Smith 2004, 2011a, 2011b, 2011c). The three species of prime
interest to medical mycology are Geotrichum candidum (Galactomyces candidus),
Magnusiomyces capitatus (previously known as Geotrichum capitatum), and
Saprochaete clavata (previously known as Geotrichum clavatum).
Geotrichum candidum is an extremely common fungus with a worldwide distribution. It
is commonly isolated from soil, air, water, milk, silage, plant tissues, and the digestive
tract in humans and other mammals (Pottier et al. 2008). Pulmonary involvement is the
most frequently reported form of the disease in humans and animals, but bronchial,
oral, vaginal, cutaneous and alimentary infections have also been noted (Arendrup et
al. 2014).
RG-1 organism.
Morphological Description: Colonies are fast growing, flat, white to cream, dry and
finely suede-like with no reverse pigment. Hyphae are hyaline, septate, branched
and break up into chains of hyaline, smooth, one-celled, subglobose to cylindrical
arthroconidia. Arthroconidia are 6-12 x 3-6 µm in size and are released by the separation
of a double septum.
Note: True blastoconidia production is not found in this genus. This characteristic
distinguishes Geotrichum from Trichosporon, which usually does produce blastoconidia.
Molecular Identification: ITS sequencing recommended for accurate species
identification (de Hoog and Smith 2004).
Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, nd No Data
Germ Tube - L-Sorbose + L-Arabinose - D-Glucitol +
Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -
Glucose v Maltose - D-Ribose - D-Gluconate -
Galactose v Cellobiose - L-Rhamnose - DL-Lactate +
Sucrose - Trehalose - D-Glucosamine - myo-Inositol -
Maltose - Lactose - N-A-D-glucosamine nd 2-K-D-gluconate -
Lactose - Melibiose - Glycerol + D-Glucuronate nd
Trehalose - Raffinose - Erythritol - Nitrate -
Assimilation Melezitose - Ribitol v Urease -
Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide nd
Galactose + D-Xylose + D-Mannitol + Growth at 37 O C v
References: Gueho (1979), Domsch et al. (1980), McGinnis (1980), Barnett et al.
(1983), Buchta and Otcenasek (1988), Samson et al. (1995), de Hoog et al. (1986,
2015), de Hoog and Smith (2004, 2011a, 2011b, 2011c).