Lichtheimia corymbifera

Synonymy:
Mycocladus corymbifera, Absidia corymbifera, Mucor corymbifera.

Recent taxonomic revisions of the genus Absidia have placed the thermotolerant species into the genus Lichtheimia (Hoffmann et al. 2007, 2009).

The genus Lichtheimia currently contains five mostly saprophytic plant decaying and soil-borne species. Lichtheimia corymbifera is the principle pathogen causing human and animal infections, however L. ramosa and L. ornata have also been reported as human pathogens (often misidentified morphologically as L. corymbifera) (Alastruey-Izquierdo et al. 2010; Walther et al., 2019).

RG-2 organism.

Lichtheimia culture

Culture of Lichtheimia corymbifera.

Morphological description: 
Colonies are fast growing, floccose, white at first becoming pale grey with age, and up to 1.5 cm high. Sporangiophores are hyaline to faintly pigmented, simple or sometimes branched, arising solitarily or in groups. Sub-sporangial septa are absent or rare. Rhizoids are very sparingly produced and may be difficult to find without the aid of a dissecting microscope to examine the colony on the agar surface. Sporangia are small (10-40 µm in diameter) and are typically pyriform in shape with a characteristic conical-shaped columella and pronounced apophysis, often with a short projection at the top. Sporangiospores vary from subglobose to oblong-ellipsoidal (3-7 x 2.5-4.5 µm), hyaline to light grey and smooth-walled. Intercalary giant cells may also be present. Temperature: optimum 35-37C; maximum 46C.

Lichtheimia microscop[y

Typical pyriform-shaped sporangium with a conical-shaped columella and pronounced apophysis of Lichtheimia corymbifera. Grocott methenamine silver (GMS) stained tissue section from a lung biopsy showing a typical sporangium of L. corymbifera.

 

Key features: 
Mucorales, small pyriform-shaped sporangia with a characteristic conical-shaped columellae and pronounced apophyses, rapid growth at 40C.

Comment: 
Morphological characteristics alone are not sufficient to reliably differentiate between L. corymbifera, L. ramosa and L. ornata. While L. ornata develops large, densely branched giant cells and L. ramosa has more ellipsoidal to cylindrical sporangiospores and a faster growth rate, these characters are often difficult to interpret. Molecular methods are needed to accurately separate these species.

Molecular identification: 
Species recognition in Lichtheimia is based on ITS and/or D1/D2 sequencing (Garcia-Hermoso et al. 2009, Alastruey-Izquierdo et al. 2010).

MALDI-TOF MS:
Direct identification of Lichtheimia species was described by Schrödl et al. (2012).

Antifungal susceptibility: Lichtheimia corymbifera (Espinel-Ingroff et al., 2015a and Australian national data); MIC µg/mL.
Antifungal No ≤0.016 0.03 0.06 0.125 0.25 0.5 1 2 4 8 16 ≥32
AMB 179     9 31 49 61 23 4   2    
ISAV 9         2 2 4 1        
VORI 41             1 6 7 24 3  
POSA 151     6 14 43 63 22 1 2      
ITRA 136     8 16 44 34 23 6 4 1    

References:

  • Alatruey-Izquierdo, A., Hoffman, K., de Hoog, G.S., et al. (2010) Species recognition and clinical relevance of the Zygomycetous genus Lichtheimia (syn, Absidia pro parte, Mycocladus). Journal of Clinical Microbiology, 48, 2154-2170.
  • 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, D.H. (2005) Systemic Zygomycetes - Mucormycosis., in Merz, W.G. and Hay, R.J. (eds), Topley and Wilson’s Microbiology and Microbial Infections: Medical Mycology 10 edition. London: Hodder Arnold, 659-686.
  • Ellis, J.J. and Hesseltine, C.W. (1965) The genus Absidia: globose spored species. Mycologia, 57. 222-235.
  • Ellis, J.J. and Hesseltine, C.W. (1966) Species of Absidia with ovoid sporangiospores. II. Sabouraudia, 5, 59-77.
  • Espinel-Ingroff, A., Chakrabarti, A., Chowdhary, A., et al. (2015) Multicenter evaluation of MIC distributions for epidemiologic cutoff value definition to detect amphotericin B, posaconazole, and itraconazole resistance among the most clinically relevant species of Mucorales. Antimicrobial Agents and Chemotherapy, 59, 1745-1750.
  • Garcia-Hermoso, D., Hoinard, D., Gantier, J.C., et al. (2009) Molecular and phenotypic evaluation of Lichtheimia corymbifera (formerly Absidia corymbifera) complex isolates associated with human mucormycosis: rehabilitation of L. ramosa. Journal of Clinical Microbiology, 47, 3862-3870.
  • Hesseltine, C.W. and Ellis, J.J. (1964) The genus Absidia: Gongronella and cylindrical-spored species of Absidia. Mycologia, 56, 568-601.
  • Hesseltine, C.W. and Ellis, J.J. (1966) Species of Absidia with ovoid sporangiospores. I. Mycologia, 58, 173-194.
  • Hoffman, K., Discher, S. and Voigt, K. (2007) Revision of the genus Absidia (Mucorales, Zygomycetes) based on physiological, phylogenetic, and morphological characters, thermotolerant Absidia spp. form a coherent group, Mycocladiaceae fam. nov. Mycological Research, 111, 1169-1183.
  • Hoffmann, K., Walther, G. and Voigt, K. (2009) Mycocladus vs. Lichtheimia, a correction (Lichtheimiaceae fam. nov., Mucorales, Mucoromycotina). Mycological Research, 113, 277-278.
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  • O’Donnell, K.L. (1979) Zygomycetes in culture. Palfrey Contributions in Botany 2. University of Georgia. pp 257.
  • Samson, R.A., Hoekstra, E.S., Frisvad, J.C., et al. (1995) Introduction to food-borne fungi. Centraalbureau voor Schimmelcultures, P.O.Box 273, 3740 AG BAARN, The Netherlands.
  • Schroedl, W., Heydel, T., Schwartze, V.U., et al. (2012) Direct analysis and identification of pathogenic Lichtheimia species by matrix-assisted laser desorption ionization-time of flight analyzer-mediated mass spectrometry. Journal of Clinical Microbiology, 50, 419-427.
  • Walther, G., Wagner, L. and Kurzai, O. (2019) Updates on the taxonomy of Mucorales with an emphasis on clinically important taxa. Journal of Fungi, 5, 106.

 

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