Acremonium sp.

Colonies are usually slow growing, often compact and moist at first, becoming powdery, suede-like or floccose with age, and may be white, grey, pink, rose or orange in color. Hyphae are fine and hyaline and produce mostly simple awl-shaped erect phialides. Conidia are usually one-celled (ameroconidia), hyaline or pigmented, globose to cylindrical, and mostly aggregated in slimy heads at the apex of each phialide. RG-2 organism.

Acremonium sp. showing long awl-shaped phialides producing cylindrical, one-celled conidia mostly aggregated in slimy heads at the apex of each phialide.

This genus is distinguished from hyaline isolates of Phialophora by the absence or very limited development of a collarette on the phialide and the predominant formation of well differentiated, awl-shaped phialides with a basal septum. Microconidial Fusarium isolates may be confused with Acremonium, but they usually grow faster and have colonies with a characteristic fluffy appearance.

For identification, potato dextrose agar and cornmeal agar are the most suitable media to use and exposure to daylight is recommended to maximize culture color characteristics.

MIC data is limited.  Antifungal susceptibility testing of individual strains is recommended.

Clinical significance:

The genus Acremonium currently contains 100 species, of which most are saprophytic, being isolated from dead plant material and soil. A number of species are recognized as opportunistic pathogens of man and animals, causing mycetoma, onychomycosis, and hyalohyphomycosis, these include A. falciforme, A. kiliense, A. recifei, A. alabamensis, A. potroni, A. roseo-griseum and A. strictum. However, many reports only identify Acremonium species to genus level. Clinical manifestations of hyalohyphomycosis caused by Acremonium; include arthritis, osteomyelitis, peritonitis, endocarditis, pneumonia, cerebritis and subcutaneous infection.

Mycosis: Hyalohyphomycosis

Further reading:

Domsch, K.H., W. Gams, and T.H. Anderson. 1980. Compendium of soil fungi. Volume 1. Academic Press, London, UK.

Kwon-Chung, K.J. and J.E. Bennett. 1992. Medical Mycology. Lea & Febiger, Philadelphia and London.