Trematosphaeria grisea

Trematosphaeria grisea (formerly Madurella grisea) is a soil fungus and is a known causative agent of mycetoma (de Hoog et al., 2004, 2012; Desnos-Ollivier et al., 2006).

RG-2 organism.

Trematosphaeria grisea

Trematosphaeria grisea showing a typical “black grain” in a haematoxylin and eosin-stained tissue section.

Morphological description: 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 1-3 µm in width or broad at 3-5 µm in width. The optimum temperature for growth of T. griseais 30oC; this fungus does not grow at 37oC.

Histopathology: Grains of Trematosphaeria 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.

Trematosphaeria grisea can be distinguished from Madurella mycetomatis by its inability to grow at 37oC, and its ability to assimilate sucrose but not lactose.

Key features: Black grain mycetoma, no growth at 37oC, no diffusible brown pigment produced on culture and absence of conidia.

References:

  • Ahmed, S.A., van de Sande, W.W.J., Stevens, D.A., et al. (2014) Revision of agents of black-grain eumycetoma in the order Pleosporales. Persoonia, 33, 141-154.
  • Chandler, F.W., Kaplan, W.and Ajello, L. (1980) A colour atlas and textbook of the histopathology of mycotic diseases. Wolfe Medical, London.
  • de Hoog, G.S., Adelmann, D., Ahmed, A.O.A., et al. (2004) Phylogeny and typification of Madurella mycetomatis, with a comparison of other agents of eumycetoma. Mycoses, 47, 121-130.
  • de Hoog, G.S., van Diepeningen, A.D., Mahgoub, el-S., et al. (2012) New species of Madurella, causative agents of black-grain mycetoma. Journal of Clinical Microbiology, 50, 988-994.
  • Desnos-Ollivier, M., Bretagne, S., Dromer, F., et al. (2006) Molecular identification of black-grain mycetoma agents. Journal of Clinical Microbiology, 44, 3517-3523.
  • Kwon-Chung, K.J. and Bennett, J.W. (1992) Medical Mycology. Lea & Febiger, Philadelphia, 861pp.
  • Tanaka, K., Hirayama, K., Yonezawa, H., et al. (2015) Revision of the Massarineae (Pleosporales, Dothideomycetes). Studies in Mycology, 82, 75-136.
  • Suetrong, S., Hyde, K.D., Zhang, Y., et al. (2011) Trematosphaeriaceae fam. nov. (Dothideomycetes, Ascomycota). Cryptogamie Mycologie, 32, 343-358.