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School of Molecular & Biomedical Science |
Aureobasidium pullulansColonies are fast growing, smooth, covered with slimy masses of conidia, cream or pink to brown or black. Hyphae are hyaline and septate, frequently becoming dark-brown with age and undergoing holothallic transformation to form chains of 1- to 2-celled, thick-walled, darkly pigmented arthroconidia commonly called chlamydoconidia. These arthroconidia actually represent the Scytalidium anamorph of Aureobasidium and are only of secondary importance in recognizing members of this genus. Conidia are produced synchronously in dense groups from indistinct scars or from short denticles on undifferentiated, hyaline to sub-hyaline hyphae. Conidia are hyaline, smooth-walled, single-celled (ameroconidia), ellipsoidal but of variable shape and size (8-12 x 4-6 um), often with an indistinct hilum (a mark or scar at the point of attachment). Temperature range for growth 2-35C; optimum 25C; maximum 35C (higher in some human pathogenic isolates).
A. pullulans showing chains of 1- to 2-celled,
darkly pigmented This species has two varieties: A. pullulans var. pullulans, with a colony which remains pink, light brown, or yellow for at least three weeks, and A. pullulans var. melanogenum which soon becomes black or greenish-black due to dark hyphae which often fall apart into separate cells. RG-1 organism.
MIC data is limited. Antifungal susceptibility testing of individual strains is recommended.
Clinical significance:Aureobasidium pullulans has a world-wide distribution and it is usually isolated as a saprophyte, occasionally from skin and nails. However, it has also been reported as a rare causative agent of phaeohyphomycosis, mycotic keratitis and peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD). Mycosis: PhaeohyphomycosisFurther reading:De Hoog, G.S., and E.J. Hermanides-Nijhof. 1977. The black yeasts and allied hyphomycetes. Studies in Mycology No. 15. Centraalbureau voor Schimmelcultures, Baarn, The Netherlands. Kwon-Chung, K.J. and J.E. Bennett. 1992. Medical Mycology. Lea & Febiger, Philadelphia and London.
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