DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 51
Chaetomium Kunze ex Fries
The genus Chaetomium contains between 160 and 180 species. All are saprophytic
being isolated from soil, straw, dung and plant debris. Several species are thermophilic
and can grow at temperatures above 37 O C. Chaetomium species are important agents
for the decomposition of cellulose waste and plant materials, and are only rarely
isolated in medical mycology laboratories. RG-1 organisms.
Morphological Description: Chaetomium is a common ascomycete characterised
by the formation of darkly-pigmented, globose, ovoid, barrel to flask-shaped, ostiolate
ascocarps (perithecia) beset with dark-coloured terminal hairs (setae) which are
straight, branched or curved. Asci are clavate to cylindrical, typically eight-spored and
evanescent. Ascospores are one-celled, darkly-pigmented, smooth-walled, of varying
shape, mostly ovoid, ellipsoidal or lemon-shaped. Chlamydospores and solitary conidia
may also be produced.
Molecular Identification: Lee and Hanlin (1999) established the phylogenetic
relationships of Chaetomium based on ribosomal DNA sequences. ITS sequencing
may be useful for identification of some clinical species.
Key Features: Ascomycete producing darkly-pigmented ostiolate perithecia beset
with long dark terminal setae.
References: Ames (1963), Seth (1970), Millner (1975), Domsch et al. (2007), Ellis and
Keane (1981), Ellis (1981), von Arx (1986), de Hoog et al. (2000, 2015).
a
100 μm 10 μm
b
Chaetomium spp. (a) ascocarps (perithecia) and (b) ascus with ascospores.
Antifungal Susceptibility: Chaetomium very limited data (McGinnis and Pasarell
1998a, Serena et al. 2003, Barron et al. 2003, Australian National Data); MIC µg/mL.
Antifungal Range MIC 90
Antifungal Range MIC 90
AmB 0.125-16 4 VORI 0.125-0.5 0.5
ITRA 0.03-0.25 0.125 POSA