DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
Three species are recognised, two of which are well known pathogens of insects.
Beauvaria bassiana is the most common species and is best known as the causal agent
of muscardine disease in silkworms. Beauveria species are occasionally isolated in the
clinical laboratory as saprophytic contaminants. Infections in humans are extremely
rare.
RG-1 organism.
Beauveria Vuillemin
Morphological Description: Colonies are usually slow growing, usually not exceeding
2 cm in ten days at 20 O C, downy, at first white, but later often becoming yellow to
pinkish. The genus Beauveria is characterised by the sympodial development of singlecelled
conidia (ameroconidia) on a geniculate or zig-zag rachis. Conidiogenous cells
are flask-shaped, rachiform, proliferating sympodially and are often aggregated into
sporodochia or synnemata. Conidia are hyaline and globose or ovoid in shape.
Key Features: Hyphomycete showing sympodial development of single-celled conidia
on a geniculate or zig-zag rachis emanating from a flask-shaped conidiophore.
Molecular Identification: Specific primers were developed by Hegedus and
Khachatourians (1996). Full phylogeny of the genus was provided by Rehner and
Buckley (2005). Biogeography of molecular types was characterised by Ghikas et al.
(2010).
MALDI-TOF MS: Cassagne et al. (2011) published a standardised procedure for mould
identification in the clinical laboratory.
References: de Hoog (1972), Domsch et al. (2007), McGinnis (1980), de Hoog et al.
(2000, 2015).
20 μm
Beauveria bassiana showing sympodial development of conidia on a geniculate or zigzag
rachis. Conidiogenous cells are flask-shaped, rachiform, proliferating sympodially
and are often aggregated into sporodochia or synnemata. Conidia are hyaline and
globose or ovoid in shape, 2-3 µm diameter (phase contrast image).