Marquandomyces marquandii

In a review of the molecular phylogeny and classification of the genus Metarhizium, Mongkolsamrit et al.(2020), have transferred Paecilomyces marquandii into a new genus as Marquandomyces marquandii.

M. marquandii is a soil fungus of worldwide distribution from temperate to tropical regions and is seldom associated with human infection.

Culture of Paecilomyces marquandii

Culture of Marquandomyces marquandii.

RG-1 organism.

Morphological description:
Colonies are fast growing, suede-like to floccose, pale vinaceous to violet coloured, with a yellow to orange yellow reverse. Conidiophores are erect, arising from submerged hyphae, 50-300 µm in length, bearing loose whorls of branches and phialides. Conidiophore stipes are 2.5-3.0 µm wide, hyaline and smooth-walled. Phialides are swollen at their bases, tapering into a thin, distinct neck. Conidia are ellipsoidal to fusiform, smooth-walled to slightly roughened, hyaline to purple in mass, 2.5-3.0 x 2-2.2 µm. Spherical to ellipsoidal chlamydospores, 3-5 µm diameter are present. No growth at 37C.

Paecilomyces marquandii conidiophores, phialides and conidia

Marquandomyces marquandii conidiophores, phialides and conidia.

Key features: Colony pigmentation with yellow reverse pigment, phialides with swollen bases, smooth conidiophore stipes, presence of chlamydospores, and no growth at 37C. Note: Purpureocillium lilacinum has no yellow reverse pigment, rough-walled conidiophore stipes, absence of chlamydospores and growth at 37C.

Antifungal susceptibility: M. marquandii very limited data (Australian national data); MIC µg/mL.

  No ≤0.03 0.06 0.125 0.25 0.5 1 2 4 8 ≥16
AmB 8       1     1 1 1 4
VORI 5   1 3     1        
POSA 3 1   1 1            
ITRA 8 1     2 3   1     1

References: 

  • Domsch, K.H., Gams, W. and Anderson, T.H. (2007) Compendium of soil fungi. Second Edition, IHW-Verlag, Germany.
  • 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.
  • Kidd, S., Halliday, C., Ellis, D. (2023) Descriptions of Medical Fungi (4th edition). CABI.
  • Mongkolsamrit, S., Khonsanit, A., Thanakitpipattana, D., et al. (2020) Revisiting Metarhizium and the description of new species from Thailand. Studies in Mycology, 95, 171-251.
  • Samson, R.A. (1974) Paecilomyces and some allied hyphomycetes. Studies in Mycology, 6, 1-120.

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