Pleurostoma

Synonymy: 
Phialophora richardsiae

Pleurostoma richardsiae is a soft rot fungus of wood and is an uncommon cause of human infection, usually through traumatic implantation causing subcutaneous phaeohyphomycosis.

Vijaykrishna et al. (2004) separated Pleurostoma richardsiae  from Phialophora based on molecular data.

P. richardsiae phillies

Phialides of Pleutostoma richardsiae producing 2 types of conidia. (1) hyaline conidia, formed on inconspicuous, peg-like phialides on thin-walled hyphae; and (2) brown, thick-walled conidia formed on dark brown, slender, tapering phialides with flaring collarettes.

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)

Antifungal susceptibility: Pleurostoma richardsiae (Australian national data); MIC µg/mL
  No ≤0.016 0.03 0.06 0.125 0.25 0.5 1 2 4 ≥8
AmB 7         1 1 4 1    
VORI 7       3 4          
POSA 7     1 2   2        
ITRA 7       2 3 2        

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