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.
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.
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.