DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
Madurella complex
The genus Madurella was originally based on tissue morphology (mycetoma with black
grains) and the formation of sterile cultures on mycological media. Initially two species
were described, M. mycetomatis and M. grisea. However recent molecular studies have
recognised five species: Madurella mycetomatis, Trematosphaeria grisea (formerly
M. grisea), M. fahalii, M. pseudomycetomatis and M. tropicana (Desnos-Ollivier et al.
2006, de Hoog et al. 2004a, 2012). All species have been isolated from soil and are
major causative agents of mycetoma. RG-2 organism.
Madurella mycetomatis (Laveran) Brumpt
Morphological Description: Colonies are slow growing, flat and leathery at first,
white to yellow to yellowish-brown, becoming brownish, folded and heaped with age,
and with the formation of aerial mycelia. A brown diffusible pigment is characteristically
produced in primary cultures. Although most cultures are sterile, two types of conidiation
have been observed, the first being flask-shaped phialides that bear rounded conidia,
the second being simple or branched conidiophores bearing pyriform conidia (3-5 µm)
with truncated bases. The optimum temperature for growth of this mould is 37 O C.
Grains of Madurella mycetomatis (tissue microcolonies) are brown or black, 0.5-1.0
mm in size, round or lobed, hard and brittle, composed of hyphae which are 2-5 µm in
diameter, with terminal cells expanded to 12-15 (30) µm in diameter.
M. mycetomatis can be distinguished from Trematosphaeria grisea by growth at 37 O C
and its inability to assimilate sucrose.
Key Features: Black grain mycetoma, growth at 37 O C, diffusible brown pigment
produced on culture and the occasional presence of phialides.
References: McGinnis (1980), Chandler et al. (1980), Rippon (1988), de Hoog et al.
(2000, 2004a, 2012, 2015), Desnos-Ollivier et al. (2006).
a
b
20 µm
Madurella mycetomatis (a) culture showing brown diffusible
pigment, and (b) phialides and conidia.