Nattrassia mangiferae

Pycnidial synanamorph: Hendersonula toruloidea
Arthroconidial synanamorphs: Scytalidium dimidiatum; Scytalidium hyalinum.

This coelomycete is characterised by the presence of black, ostiolate pycnidia containing numerous hyaline, flask-shaped phialides. Phialoconidia are at first one-celled and hyaline, later becoming three-celled and brown, with the centre cell darker than the end cells. Conidia are ovoid to ellipsoidal in shape. Pycnidia are only occasionally formed in older cultures. In culture the Scytalidium dimidiatum anamorph is typically present showing chains of one- to two-celled, darkly pigmented arthroconidia, 3.5-5 x 6.5-12 µm, produced by the holothallic fragmentation of undifferentiated hyphae. Cultures are effuse, hairy, dark grey to blackish-brown, or white to greyish, with a cream-coloured to deep ochraceous-yellow colony reverse. Colourless (hyaline) mutants (=Scytalidium hyalinum) often occur.

Microscopic morphology of the Scytalidium dimidiatum synanamorph of Nattrassia mangiferae showing chains of one- to two-celled, darkly pigmented arthroconidia.

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

Clinical significance:

Nattrassia mangiferae (arthric synanamorph = Scytalidium dimidiatum) is a recognised agent of onychomycosis and superficial skin infections, especially in tropical regions. However, isolates are sensitive to cycloheximide (actidione) which is commonly added to primary isolation media used for culturing skin scrapings. RG-2 organism.

Mycosis: Dermatomycosis

Further reading:

Frankel,D.H. and J.W. Rippon. 1989. Hendersonula toruloidea infection in man. Mycopathologia 105:175-186.

Sutton, B.C. and B.J. Dyko. 1989. Revision of Hendersonula. Mycol. Res. 93:466-488.