Correct Answer

C. Trichosporon asahii

The fungus was identified as Trichosporon asahii (MALDI-TOF MS), a basidiomycetous yeast found in the environment and as part of the gastrointestinal flora of birds and animals. It can also be isolated from human skin, the gastrointestinal tract, oropharynx, and respiratory tract.

Trichosporon asahii is an opportunistic pathogen causing infections in immunocompromised patients, with a mortality rate of approximately 64%. Fungemia is the most common clinical presentation of invasive infection caused by Trichosporon, and is particularly associated with central venous catheters, which the fungus colonizes and forms biofilms on.

Morphology and Diagnosis

Colonies are white to creamy, brain-like in appearance, and microscopic examination shows blastoconidia, hyphae, pseudohyphae, and arthroconidia. It is urease-positive and does not form germ tubes. Identification can be achieved via: sugar assimilation tests (e.g., API 20 C AUX, API ID 32 C), automated biochemical systems (e.g., Vitek 2), MALDI-TOF MS.

Resistance Profile

Trichosporon asahii exhibits intrinsic resistance to echinocandins, which can lead to breakthrough infections in patients on these antifungal agents.

Treatment: Voriconazole (or posaconazole) is the treatment of choice. Amphotericin B is a second-line option.

References

  1. Commenges A, Coucheney F, Lessard MH, Drider D, Steve Labrie S. Trichosporon asahii: Taxonomy, health hazards, and biotechnological applications. Fungal Biology Reviews 2024; 100369, https://doi.org/10.1016/j.fbr.2024.100369
  2. Chen SC, Perfect J, Colombo AL, Cornely OA, Groll AH, Seidel D, Albus K, de Almedia JN Jr, Garcia-Effron G, Gilroy N, Lass-Flörl C, Ostrosky-Zeichner L, Pagano L, Papp T, Rautemaa-Richardson R, Salmanton-García J, Spec A, Steinmann J, Arikan-Akdagli S, Arenz DE, Sprute R, Duran-Graeff L, Freiberger T, Girmenia C, Harris M, Kanj SS, Roudbary M, Lortholary O, Meletiadis J, Segal E, Tuon FF, Wiederhold N, Bicanic T, Chander J, Chen YC, Hsueh PR, Ip M, Munoz P, Spriet I, Temfack E, Thompson L, Tortorano AM, Velegraki A, Govender NP. Global guideline for the diagnosis and management of rare yeast infections: an initiative of the ECMM in cooperation with ISHAM and ASM. Lancet Infect Dis. 2021;21(12):e375-e386. doi: 10.1016/S1473-3099(21)00203-6