Madurella grisea

Colonies are slow growing, dark, leathery, folded with radial grooves and with a light brown to greyish surface mycelium. With age colonies become dark brown to reddish-brown and have a brownish-black reverse. Microscopically cultures are sterile although hyphae of two widths have been described, thin at 1 to 3 um in width or broad at 3 to 5 um in width. The optimum temperature of growth for M. grisea is 30C, it does not grow at 37C.  RG-2 organism.

Grains of Madurella grisea (tissue microcolonies) are black, round to lobed, soft to firm, up to 1.0 mm, with two distinctive zones, a hyaline to weakly pigmented central zone and a deeply pigmented periphery.

M. grisea can be distinguished from Madurella mycetomatis by the inability to grow at 37C and to assimilate lactose.

MIC data is limited.  Antifungal susceptibility testing of individual strains is recommended.

Clinical significance:

The genus Madurella is based on tissue morphology (mycetoma with black grains) and the formation of sterile cultures on mycological media and is in need of revision. Both M. mycetomatis and M. grisea have been isolated from soil and are one of the major causative agents of mycetoma.

Mycosis: Mycetoma

Further reading:

Kwon-Chung, K.J. and J.E. Bennett. 1992. Medical Mycology. Lea & Febiger, Philadelphia and London.