Papiliotrema laurentii

Synonymy: Cryptococcus laurentii

Papiliotrema laurentii is an emerging opportunistic pathogen, causing disease in patients with impaired cell-mediated immunity (eg, HIV-infected patients or those with haematologic malignancies), in those using steroids or chemotherapeutic agents, and in those with invasive devices.  

Human infections due to P. laurentii have been described as causing fungaemia, central nervous system infection, skin and soft-tissue infections, and pneumonia, among others.

RG-1 organism.

Culture: 
Colonies (SDA) are cream-coloured, often becoming a deeper orange-yellow with age, with a smooth mucoid texture.

Microscopy: 
Spherical and elongated budding yeast-like cells or blastoconidia, 2.0- 5.5 x 3.0-7.0 μm. No pseudohyphae present.

India ink preparation: 
Positive - narrow but distinct capsules are present.

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

Note: 
Some strains of Papiliotrema laurentii may develop brown pigment on bird seed agar and turn CGB media blue, similar to Cryptococcus gattii, however P. laurentii assimilates both lactose and melibiose while C. gattii does not. Impaired cellular immunity is the most common risk factor with HIV infection and low CD4 counts a common comorbidity. Invasive devices are an additional risk factor.

Antifungal susceptibility: Papiliotrema laurentii (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 7     1 2 3 1            
FLU 6             1 1   3   1
VORI 6   2     2 1     1      
POSA 5 1 1 2   1              
ITRA 7 1   2 2 1           1  
5FC 7                       7