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Diutina

Two species previously classified in the genus Candida have now been transferred to the genus Diutina. Diutina catenulata (formerly Candida catenulata) and Diutina rugosa complex (formerly rugosa complex).

Species Descriptions

  • Diutina catenulata

    Synonymy: 
    Candida catenulata

    Although most isolates of Diutina catenulata originate from human sources, cases of candidaemia are uncommon.

    RG-1 organism. 

    Culture: 
    Colonies (SDA) white to cream-coloured smooth, soft and wrinkled, yeast-like.

    Microscopy: 
    Ovoid to cylindrical budding blastoconidia, 1.5-4.5 x 4-12 µm.

    India Ink Preparation: 
    Negative - no capsules present.

    Dalmau Plate Culture:
    Pseudohyphae consisting of chains of ovoid or cylindroid cells, and sometimes small verticils of ovoid blastoconidia.

    Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, nd No Data
    Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol v
    Fermentation Sucrose - D-Arabinose - 𝝰-M-D-glucoside -
    Glucose v Maltose v D-Ribose v D-Gluconate v
    Galactose -,s Cellobiose - L-Rhamnose - DL-Lactate -
    Sucrose - Trehalose v D-Glucosamine v myo-Inositol -
    Maltose -,s Lactose - NAD-glucosamine + 2KD-Gluconate v
    Lactose - Melibiose - Glycerol + D-Glucuronate -
    Trehalose - Raffinose - Erythritol - Nitrate -
    Assimilation Melezitose - Ribitol v Urease -
    Glucose + Soluble Starch v Galactitol - 0.1% Cyclohgeximide +,s
    Galactose + D-Xylose v D-Mannitol + Growth at 40C v

    Key Features: 
    Separation from most physiologically similar species can be accomplished based on positive growth responses on D-mannitol, D-glucitol and resistance to 0.1% cycloheximide, combined with negative responses for sorbose and erythritol utilisation or growth in vitamin-free medium.

    Antifungal Susceptibility: Diutina catenulata (Australian National data); MIC µg/mL.
    No <0.016 0.03 0.06 0.125 0.25 0.5 1 2 4 8 16 >32
    AmB 3 2 1
    FLU 3 1 1 1
    VORI 3 2 1
    POSA 3 2 1
    ITRA 3 1 1 1
    ANID 3 1 2
    MICA 3 1 2
    CAS 3 1 2
    5FC 3 3
  • Diutina rugosa complex

    Diutina rugosa has recently been recognised as a species complex of D. rugosa, D. pseudorugosa and another as yet undescribed species (Li et al. 2006, Paredes et al. 2012). These species are best identified by ITS sequencing.

    Diutina rugosa 

    RG-1 organism. 

    Culture: 
    Colonies (SDA) white to cream-coloured smooth, glabrous, yeast-like.

    Microscopy: 
    Ellipsoidal to elongate budding blastoconidia, 5-11 x 1.5-2.5 µm. Sometimes short pseudohyphae may be produced.

    India Ink Preparation: 
    Negative - no capsules present.

    Dalmau Plate Culture: 
    Densely branched pseudohyphae produced.

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

    Key Features: 
    Germ tube negative yeast and sugar assimilation pattern (D-Xylose and Glycerol +ve; Ribitol -ve.). C. rugosa has been associated with catheter related fungaemia and has been isolated from human and bovine faeces, sea water and soil.

    Antifungal Susceptibility:  Diutina rugosa limited data (Diekema et al. 2009, Espinal-Ingroff et al. 2014 and Australian National data); MIC µg/mL
    No <0.03 0.06 0.12 0.25 0.5 1 2 4 8 16 32 >64
    AmB 21 1 1 5 5 7 1 1
    FLU 97 1 3 15 24 29 8 8 6 1 2
    VORI 80 50 16 4 7 3
    POSA 66 17 27 9 8 5
    ITRA 5 1 1 1 1 1
    ANID 20 3 4 4 4 3 2
    MICA 20 2 3 5 6 2 2
    CAS 25 1 1 2 3 10 1 1 2

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