Acremonium Link ex Fries
The genus Acremonium contains many species; most are saprophytic being isolated from dead plant material and soil. Several species including A. recifei and A. alabamense are recognised as opportunistic pathogens of man and animals, causing mycetoma, mycotic keratitis and onychomycosis. Recently, several Acremonium-like species recognised as opportunistic pathogens have been transferred to other genera; Fusarium falciforme (formerly A. falciforme), Sarocladium kiliense (formerly A. kiliense), Gliomastic roseogriseum (formerly A. roseogriseum) and Sarocladium strictum (formerly A. strictum) (Glenn et al. 1996, Summerbell et al. 2011).
RG-2 for species isolated from humans.
Morphological Description: 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 colour. Hyphae are fine and hyaline and produce mostly simple awl-shaped erect phialides with inconspicuous collarettes. Conidia are usually one-celled, hyaline or rarely pigmented, globose to cylindrical, and mostly aggregated in slimy heads at the apex of each phialide. Chlamydospores may be present.
Comments: Microconidial Fusarium isolates may be confused with Acremonium, but they usually grow faster and have colonies with a characteristic fluffy appearance. Phialemonium species differ by having short, tapering phialides, mostly lacking a basal septum. Coniochaeta is characterised by having sessile phialidic collarettes that are formed directly on the hyphae.
Molecular Identification: Summerbell et al. (2011) revised the genus on the basis of 18S and D1/D2 sequence phylogeny. Sequence based identification may be performed using the D1/D2 or the ITS region. Caution must be exercised though in the interpretation of database sequence comparisons due to the scarcity of database sequences from well-characterised strains, and some sequences may have been attributed to species that have been reclassified (Perdomo et al. 2011a).
Acremonium sp. showing long awl-shaped phialides producing cylindrical, one-celled conidia mostly aggregated in slimy heads at the apex of each phialide.
Antifungal Susceptibility: Acremonium species data from about 60 isolates (Perdomo et al. 2011 and Australian National data); MIC µg/mL.