Phialophora verrucosa
The genus Phialophora contains more than 40 species, most are saprophytes commonly found in soil or on decaying wood.
Some human pathogens with phialidic conidiogenesis previously assigned to Phialophora have been moved to other genera, namely, Phaeoacremonium and Pleurostomophora. P. verrucosa, P. americana, P. bubakii, P. europaea and P. reptans remain of medical interest (Revankar and Sutton 2010). Both P. verrucosa and P. americana produce their conidia from phialides with conspicuous darkened collarettes, however sequencing has demonstrated a close relatedness, suggesting that these species may be synonymous (de Hoog et al. 1999). P. verrucosa is primarily an agent of chromoblastomycosis although other reported infections include endocarditis, keratitis, and osteomyelitis (Li et al., 2017).
Phialides and conidia of P. verrucosa.
RG-2 organism.
Morphological description:
Colonies (SDA) are slow growing, initially dome-shaped, later becoming flat, suede-like and olivaceous to black in colour. Phialides are flask-shaped or elliptical with distinctive funnel-shaped, darkly pigmented collarettes. Conidia are ellipsoidal, smooth-walled, hyaline, mostly 3.0-5.0 x 1.5-3.0 μm, and aggregate in slimy heads at the apices of the phialide.
Key features:
Characteristic flask-shaped phialides with distinctive funnel-shaped, darkly pigmented collarettes.
Molecular identification:
ITS sequencing recommended (de Hoog et al. 1999).
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Antifungal susceptibility: Phialophora verrucosa limited data (Australian national data); MIC µg/mL. |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No | ≤0.03 | 0.06 | 0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | ≥32 | |
| AmB | 7 | 1 | 4 | 2 | ||||||||
| VORI | 7 | 1 | 3 | 3 | ||||||||
| POSA | 5 | 2 | 4 | 1 | ||||||||
| ITRA | 7 | 1 | 4 | 2 | ||||||||
References:
- de Hoog, G.S., Weenink, X.O. and Gerrits van den Ende, A.H.G. (1999) Taxonomy of the Phialophora verrucosa complex with the description of two new species. Studies in Mycology, 43, 107-122.
- de Hoog, G.S., Guarro, J., Gene, J., et al. (2015) Atlas of Clinical Fungi (Version 4.1.2). Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands.
- Domsch, K.H., Gams, W. and Anderson, T.H. (2007) Compendium of soil fungi. Second Edition, IHW-Verlag, Germany.
- Ellis, M.B. (1971) Dematiaceous hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England.
- Kidd, S., Halliday, C., Ellis, D. (2023) Descriptions of Medical Fungi (4th edition). CABI.
- Li, Y., Xiao, J., de Hoog, G.S., et al. (2017) Biodiversity and human-pathogenicity of Phialophora verrucoseand relatives in Chaetothyriales. Persoonia, 38, 1-19.
- McGinnis, M.R. (1978b) Human pathogenic species of Exophiala, Phialophora, and Wangiella. In the black and white yeasts. Proceedings of the fourth international conference on the mycoses. Scientific Publication No. 356. Pan American Health Organization. Washington, DC, USA. pp.37-59.
- McGinnis, M.R. (1980) Laboratory handbook of medical mycology. Academic Press, New York.
- Revankar, S.G. and Sutton, D.A. (2010) Melanized fungi in human disease. Clinical Microbiology Reviews, 23, 884-928.