Candida orthopsilosis
Candida orthopsilosis is recognised as part of the Candida parapsilosis species complex (Tavanti et al., 2005).
It is phenotypically indistinguishable from C. parapsilosis, C. metapsilosis and Lodderomyces elongisporus and is best identified by ITS sequencing or MALDI-ToF MS.
RG-2 organism.
Culture:
Colonies (SDA) white to cream-coloured smooth, glabrous, yeast-like.
Microscopy:
Ellipsoid to subglobose budding blastoconidia, 2-5 x 3-7 µm, with some larger elongated forms present.
India ink preparation:
Negative - no capsules present.
Dalmau plate culture:
Abundant, much-branched pseudohyphae produced.
| 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 | + | |
| Glucose | + | Maltose | + | D-Ribose | - | D-Gluconate | + |
| Galactose | - | Cellobiose | - | L-Rhamnose | - | DL-Lactate | - |
| Sucrose | - | Trehalose | + | D-Glucosamime | - | myo-Inositol | - |
| Maltose | - | Lactose | - | N-A-D-glucosamine | + | 2-K-D-Gluconate | + |
| Lactose | - | Melibiose | - | Glycerol | + | D-Glucuronate | - |
| Trehalose | -,s | Raffinose | - | Erythritol | - | Nitrate | - |
| Assimilation | Melezitose | + | Ribitol | + | Urease | - | |
| Glucose | + | Soluble Starch | v | Galactitol | - | 0.1% Cycloheximide | - |
| Galactose | + | D-Xylose | + | D-Mannitol | + | Growth at 37C | + |
Key features:
Candida orthopsilosis cannot be distinguished morphologically from C. parapsilosis and C. metapsilosis, but can be identified by ITS sequencing (Asadzadeh et al. 2009, Borman et al. 2009, Tavanti et al. 2005) and MALDI-TOF MS analysis.
| Antifungal | No | ≤0.016 | 0.03 | 0.06 | 0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | ≥64 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMB | 224 | 3 | 3 | 30 | 46 | 61 | 49 | 23 | 9 | |||||
| FLU | 199 | 1 | 9 | 47 | 86 | 24 | 16 | 9 | 4 | 3 | ||||
| ISAV | 3 | 1 | 1 | 1 | ||||||||||
| VORI | 179 | 70 | 51 | 36 | 6 | 13 | 2 | 2 | ||||||
| POSA | 139 | 5 | 22 | 50 | 42 | 9 | 11 | |||||||
| ITRA | 97 | 3 | 14 | 32 | 32 | 16 | ||||||||
| ANID | 89 | 1 | 3 | 9 | 20 | 46 | 10 | |||||||
| MICA | 88 | 1 | 1 | 3 | 37 | 39 | 6 | 1 | ||||||
| 5FC | 95 | 58 | 22 | 9 | 3 | 1 | 1 | 1 |
References
- Asadzadeh, M., Ahmad, S., Al-Sweih, N., et al. (2009) Rapid molecular differentiation and genotypic heterogeneity among Candida parapsilosis and Candida orthopsilosis strains isolated from clinical specimens in Kuwait. Journal of Medical Microbiology, 58, 745-752.
- Borman, A.M., Linton, C.J. Oliver, D., et al. (2009) Pyrosequencing analysis of 20 nucleotides of internal transcribed spacer 2 discriminates Candida parapsilosis, Candida metapsilosis, and Candida orthopsilosis. Journal of Clinical Microbiology, 47, 2307-2310.
- Tavanti, A., Davidson, A.D., Gow, N.A., et al. (2005) Candida orthopsilosis and Candida metapsilosis spp. nov. to replace Candida parapsilosis groups II and III. Journal of Clinical Microbiology, 43, 284-292.
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