Saccharomyces cerevisiae

Synonomy: 
Candida robusta

Saccharomyces cerevisiae, commonly known as Baker’s yeast, may be found as a harmless and transient digestive commensal and coloniser of mucosal surfaces of normal individuals.

The anamorphic state of S. cerevisiae is sometimes referred to as Candida robusta. This species is phylogenetically closely related to Candida glabrata and shares many clinical and microbiological characteristics to this species (Arendrup et al. 2014). S. cerevisiae may be involved in mucosal infections like vaginitis, and in bloodstream infections, particularly in fluconazole-exposed patients. 

Note: Saccharomyces boulardii, a genetically similar subtype that is used as a probiotic for prevention and treatment of various sorts of diarrhoea and recurrent Clostridium difficile-associated diarrhoea should be avoided in immunocompromised hosts (Enache-Angoulvant and Hennequin 2005, Arendrup et al. 2014).

RG-1 organism.

Morphological description: 
Colonies are white to cream, smooth, glabrous and yeast-like. Large globose to ellipsoidal budding yeast-like cells or blastoconidia, 3.0-10.0 x 4.5-21.0 µm. No capsules present on India Ink preparation.

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, nd No Data
Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -
Fermentation   Sucrose + D-Arabinose - 𝝰-M-D-Glucoside nd
Glucose + Maltose + D-Ribose - D-Gluconate -
Galactose v Cellobiose - L-Rhamnose - DL-Lactate v
Sucrose + Trehalose + D-Glucosamime - myo-Inositol -
Maltose v Lactose - N-A-D-glucosamine - 2-K-D-Gluconate nd
Lactose - Melibiose v Glycerol - D-Glucuronate nd
Trehalose - Raffinose + Erythritol - Nitrate -
Assimilation   Melezitose v Ribitol - Urease -
Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -
Galactose v D-Xylose - D-Mannitol - Growth at 37C -

Molecular identification: 
ITS and/or D1/D2 sequencing is recommended (McCullough et al. 1988).

Antifungal susceptibility: Saccharomyces cerevisiae ( (Australian national data); MIC µg/mL.
Antifungal No ≤0.03 0.06 0.125 0.25 0.5 1 2 4 8 16 32 ≥64
AMB 116 1 1 9 22 36 43 3 1        
FLU 117         4 10 27 18 11 24 13 4
ISAV 24 13 3 3 3 1 1            
VORI 112 28 23 16 29 12 3 1          
POSA 110   3 7 32 21 32 12   3      
ITRA 117   3 24 31 29 23 3 1   3    
ANID 107 7 14 58 22 6              
MICA 107 1 9 69 25 3              
CAS 36   2 3 11 14 5 1          
5FC 117 8 98 8         1 1 1    

References

  • Arendrup, M.C., Boekhout, T., Akova, M., et al. (2014) ESCMID and ECMM joint clinical guidelines for the diagnosis and management of rare invasive yeast infections. Clinical Microbiology and Infection, 20, Suppl 3, 76-98.
  • Barnett, J.A., Payne, R.W. and Yarrow, D. (1983) Yeasts: characteristics and identification. Cambridge University Press, Cambridge, UK.
  • 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.
  • Enache-Angoulvant, A. and Hennequin, C. (2005) Invasive Saccharomyces infection: a comprehensive review. Clinical Infectious Diseases, 41, 1559-1568.
  • McCullough, M.J., Clemons, K.V., McCusker, J.H., et al. (1998) Intergenic transcribed spacer PCR ribotyping for differentiation of Saccharomyces species and interspecific hybrids. Journal of Clinical Microbiology, 36, 1035-1038.
  • McGinnis, M.R. (1980) Laboratory handbook of medical mycology. Academic Press, New York.
  • Rippon, J.W. (1988) Medical mycology: the pathogenic fungi and the pathogenic actinomycetes, 3rd edition. W,B. Saunders Co, Philadelphia, USA.
  • Vaughan-Martini, A. and Martini, A. (2011) Chapter 61, Saccharomyces Meyen ex Reess (1870), in Kurtzman, C.P., Fell, J.W. and Boekhout, T. (eds), The Yeasts, a Taxonomic Study, 5th edition, Elsevier B.V., pp. 733-746.

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