Schizophyllum (Basidiomycota)

Schizophyllum commune 

Schizophyllum commune is a common basidiomycete bracket fungus found on rotten wood, and is an occasional human pathogen, principally associated with sinusitis, allergic bronchopulmonary mycosis and as a contaminant from respiratory specimens.

However the introduction of DNA sequencing and/or MALDI-TOF MS identification in the clinical laboratory has seen many more cases of S. commune fungal rhinosinusitis identified (Michel et al. 2012, Chowdhary et al. 2013a, 2014a,b).

RG-1 organism.

Schizophyllum1

Basidiocarps of Schizophyllum commune on malt extract agar.

Morphological description: 
Colonies on 2% malt extract agar are spreading, woolly, whitish to pale greyish-brown, soon forming macroscopically visible fruiting bodies. Some isolates may take up to 12 weeks to form fruiting bodies. Fruit bodies are sessile, kidney-shaped, lobed with split gills on the lower side. Hyphae are hyaline, wide and have clamp connections. Basidia bear four basidiospores on erect sterigmata. Basidiospores hyaline, smooth-walled, elongate with lateral scar at lower end, 6-7 x 2-3 µm.

Schizophyllum2

Basidiocarps of Schizophyllum commune on malt extract agar.

Note: 
Many clinical isolates of S. commune are monokaryotic and do not show clamp connections, therefore any white, rapidly growing, sterile isolate showing good growth at 37C with tolerance to benomyl, susceptibility to cycloheximide, and a pronounced odour should be suspected of being S. commune (Sigler et al. 1995).

Molecular identification: 
Sequencing of the ITS and D1/D2 regions is recommended (Buzina et al. 2001, Won et al. 2012, Chowdhary et al. 2013b, Michel et al. 2012), however the number of well identified nucleotide sequences of these fungi in the GenBank database remains limited.

MALDI-TOF MS: 
Michel et al. (2012), Chowdhary et al. (2014b), Huguenin et al. (2015) provide identification procedures, however the number of mass spectral profiles to be found in MALDI-TOF libraries remains limited.

Antifungal Susceptibility: Schizophyllum commune (Chowdhary et al. 2013b); MIC µg/mL.
Antifungal Range MIC90 Antifungal Range MIC90
AMB 0.03-2 1 FLU 2-64 64
ITRA 0.03-8 1 VORI 0.06-2 0.5

References

  • Chowdhary, A., Randhawa, H.S., Gaur, S.N., et al. (2013a) Schizophyllum commune as an emerging fungal pathogen: a review and report of two cases. Mycoses, 56, 1-10.
  • Chowdhary, A., Kathuria, S., Singh, P.K., et al. (2013b) Molecular characterization and in vitro antifungal susceptibility profile of Schizophyllum commune, an emerging Basidiomycete in bronchopulmonary mycoses. Antimicrobial Agents and Chemotherapy, 57, 2845-2848.
  • Chowdhary, A., Khaturia, S., Agarwal, K., et al. (2014a) Recognizing filamentous basidiomycetes as agents of human disease: A review. Medical Mycology, 52, 782-797.
  • Chowdhary, A., Agarwal, K., Kathuria, S., et al. (2014b) Allergic bronchopulmonary mycosis due to fungi other than Aspergillus: a global overview. Critical Reviews in Microbiology, 40, 30-48.
  • Buzina, W., Lang-Loidolt, D., Braun, H., et al. (2001) Development of molecular methods for identification of Schizophyllum commune from clinical samples. Journal of Clinical Microbiology, 39, 2391-2396.
  • 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.
  • Huguenin, A., Lorot, A. and D. Zachar. (2015) Matrix-assisted laser desorption ionization-time of flight identification of Schizophyllum commune: perspectives on the review by Chowdhary et al. Medical Mycology, 53, 896-897.
  • McGinnis, M.R. (1980) Laboratory handbook of medical mycology. Academic Press, New York.
  • Michel, J., Maubon, D., Varoquaux, D.A., et al. (2015) Schizophyllum commune: an emergent or misdiagnosed fungal pathogen in rhinology? Medical Mycology, 54, 301-309.
  • Morton, F.J. and Smith, G. (1963) The genera Scopulariopsis Bainier, Microascus Zukal, and Doratomyces Corda. Mycological Papers, No, 86. Commonwealth Mycological Institute, Kew, London.
  • Rippon, J.W. (1988) Medical mycology: the pathogenic fungi and the pathogenic actinomycetes, 3rd edition. W,B. Saunders Co, Philadelphia, USA.
  • Sigler, L., de la Maza, L.M., Tan, G., et. al. (1995) Diagnostic difficulties caused by a nonclamped Schizophyllum commune isolate in a case of fungus ball of the lung. Journal of Clinical Microbiology, 33, 1979-1983.
  • Won, E.J., Shin, J.H., Lim, S.C., et al. (2012) Molecular identification of Schizophyllum commune as a cause of allergic fungal sinusitis. Annals of Laboratory Medicine, 32, 375-379.