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Mould Identification: A Virtual Self Assessment

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Unknown 39 = Alternaria alternata

Case History
Two years after lung transplantation, a 53-year-old patient presented with a tumor-like lesion on his thigh, with a history of a penetrating injury caused by a splinter acquired during hiking. The lesion was excised completely, and microscopic examination revealed a filamentous fungal infection. The culture shown below was isolated.
Clinical Presentation

Subcutaneous phaeohyphomycosis following a non-penetrating injury.

Colonies are fast growing, black to olivaceous-black or greyish, and are suede-like to floccose.

Microscopically, branched acropetal chains (blastocatenate) of multicelled conidia (dictyoconidia) are produced sympodially from simple, sometimes branched, short or elongate conidiophores. Conidia are obclavate, obpyriform, sometimes ovoid or ellipsoidal, often with a short conical or cylindrical beak, pale brown, smooth-walled or verrucose. Temperature: optimum 25-28C; maximum 31-32C. RG-1 organism.
Comment: Alternaria is a ubiquitous genus containing common saprophytes in soil and air, and plant pathogens. Although usually seen as saprophytic contaminants, Alternaria species in particular A. alternata and A. infectoria are recognised causative agents of subcutaneous phaeohyphomycosis and mycotic keratitis. They are a rare cause of onychomycosis, usually following trauma to the nail.

About Alternaria Back to Virtual Assessment

What is your identification?

Ulocladium chartarum
Exserohilum rostratum
Alternaria alternata

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School of Biological Sciences



Dr David Ellis