Malbranchea sp.

Colonies are white to sulphur-yellow to ocher-brown in colour, suede-like in texture, with a reddish-brown reverse, and often a reddish diffusible pigment. Microscopic morphology shows typical hyaline, one-celled, cylindrical, truncate, alternate arthroconidia produced in terminal fertile portions of the hyphae. Arthroconidia are released by lysis of the disjunctor cells. These arthroconidia may be perceived as a yellow dust when released at maturity.  RG-1 organism.

Arthroconidia of Malbranchea sp.

Clinical significance:

Malbranchea species are soil fungi of world-wide distribution which microscopically resemble Coccidioides immitis. Exoantigen tests are now the method of choice for culture identification of C. immitis.

Mycosis: Hyalohyphomycosis

Further reading:

McGinnis, M.R. 1980. Laboratory handbook of medical mycology. Academic Press, London, UK.

Rippon, J.W. 1988. Medical Mycology. 3rd Edition. W.B. Saunders Co., Philadelphia, USA.