Malbranchea pulchella
Malbranchea species are soil fungi of worldwide distribution which microscopically may resemble Coccidioides immitis/posadasii.
Note: Culture identification by exoantigen test or ITS sequencing is the method of choice for identification of C. immitis/posadasii.
Malbranchea pulchella arthroconidia produced in tightly coiled, terminal fertile branches of the hyphae.
RG-1 organism.
Morphological description:
Colonies are white to sulphur-yellow to ochre-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 tightly coiled, terminal fertile branches 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.
Key features:
Hyphomycete producing alternate arthroconidia with disjunctor cells.
References:
- Cooney, D.H. and Emerson, R. (1964) Thermophilic fungi; an account of their biology, activities, and classification. W.H. Freeman & Co, San Francisco and London.
- de Hoog, G.S., Guarro, J., Gene, J., et al. (2015) Atlas of Clinical Fungi (Version 4.1.2). Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands.
- Kidd, S., Halliday, C., Ellis, D. (2023) Descriptions of Medical Fungi (4th edition). CABI.
- McGinnis, M.R. (1980) Laboratory handbook of medical mycology. Academic Press, New York.
- Rippon, J.W. (1988) Medical mycology: the pathogenic fungi and the pathogenic actinomycetes, 3rd edition. W,B. Saunders Co, Philadelphia, USA.
- Sigler, L. and Carmichael, J.W. (1976) Taxonomy of Malbranchea and some other hyphomycetes with arthroconidia. Mycotaxon, 4, 349-488.