DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 159
Pleurostomophora richardsiae (Nannf.) Mostert et al.
Synonymy: Phialophora richardsiae (Nannf.) Conant.
Vijaykrishna et al. (2004) separated Pleurostomophora richardsiae from Phialophora
based on molecular data. P. richardsiae is a soft rot fungus of wood and is an
uncommon cause of human infection, usually through traumatic implantation causing
subcutaneous phaeohyphomycosis. RG-2 organism.
Morphological Description: Colonies grow rapidly, and are powdery to woolly or
tufted, greyish-brown with a grey-brown to olivaceous-black reverse. Two conidial
types are produced: (1) hyaline conidia which are allantoid or cylindrical, 3-6 x 1.5-2.5
μm in size, formed on inconspicuous, peg-like phialides on thin-walled hyphae; and
(2) brown, thick-walled conidia which are spherical to subspherical, 2.5-3.5 x 2-3 μm,
formed on dark brown, slender, tapering phialides with flaring collarettes.
Key Features: P. richardsiae is characterised microscopically by phialides with
prominent flaring collarettes bearing globose, brown conidia while phialides with
indistinct collarettes bear pale allantoid to cylindrical conidia.
Molecular Identification: ITS sequencing is recommended (Vijaykrishna et al. 2004).
References: Ellis (1971), McGinnis (1978a, 1980), Domsch et al. (1980), de Hoog et
al. (2000, 2015), Vijaykrishna et al. (2004), Revankar and Sutton (2010).
2
10 µm
1
10 µm
Pleurostomophora richardsiae phialides producing two types of conidia.
(1) hyaline conidia, and (2) brown, thick-walled conidia (arrows).
Antifungal Susceptibility: Pleurostomophora richardsiae limited data (Australian
National data); MIC µg/mL.
No. 64
AmB 7 1 1 4 1
VORI 7 3 4
POSA 5 1 2 2
ITRA 7 2 3 2 1
P. richardsiae data from 11 isolates (McGinnis and Pasarell 1998a); MIC µg/mL.
AmB Range 0.125-1; Geometric mean = 0.73
VORI Range 0.25-2; Geometric mean = 0.64
ITRA Range 0.03-2; Geometric mean = 0.44