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