Exophiala dermatitidis: Key issues of an opportunistic fungal pathogen

Abstract

The black yeast Exophiala dermatitidis is an opportunistic pathogen, causing phaeohyphomycosis in immunosuppressed patients, chromoblastomycosis and fatal infections of the central nervous system in otherwise healthy Asian patients. In addition, it is also regularly isolated from respiratory samples from cystic fibrosis patients, with rates varying between 1% and 19%.Melanin, as part of the cell wall of black yeasts, is one major factor known contributing to the pathogenicity of E. dermatitidis and increased resistance against host defense and anti-infective therapeutics. Further virulence factors, e.g. the capability to adhere to surfaces and to form biofilm were reported. A better understanding of the pathogenicity of E. dermatitidis is essential for the development of novel preventive and therapeutic strategies. In this review, the current knowledge of E. dermatitidis prevalence, clinical importance, diagnosis, microbiological characteristics, virulence attributes, susceptibility, and resistances as well as therapeutically strategies are discussed.

The Neurotropic Black Yeast Exophiala dermatitidis Induces Neurocytotoxicity in Neuroblastoma Cells and Progressive Cell Death

“…Exophiala dermatitidis is the most clinically important and thermotolerant species of the genus Exophiala. It can cause various medical conditions, from cutaneous and subcutaneous infections, to systemic, gastrointestinal, pulmonary, and neurotropic infections [9]. It has been isolated from the ears, sinuses, lungs, mucus of cystic fibrosis patients, blood and different catheters, and most importantly brain infections [3,[10][11][12][13][14][15][16][17][18][19][20][21].…”

“…Occasionally, it can cause mildly invasive systemic infections that are associated with significant morbidity and mortality. Typical infections are seen in immunocompromised hosts such as transplant recipients, oncology, and pediatric patients, where it manifests itself as a subcutaneous disease and rarely as deep mycoses [9,[22][23][24][25][26]. Particularly in East Asia, E. dermatitidis was detected in disseminated and neurotropic infections with high mortality [11,27].…”

“…Its pathogenicity is probably owing to various virulence factors, including melanin pigmentation, thermotolerance, and polymorphism [9]. Melanin accumulates in the cell wall of E. dermatitidis.…”

Phenotypical Characteristics of the Black Yeast Exophiala dermatitidis Are Affected by Pseudomonas aeruginosa in an Artificial Sputum Medium Mimicking Cystic Fibrosis–Like Conditions

“…The black yeast-like fungus Exophiala dermatitidis (Ed) frequently colonizes the respiratory tract of CF patients; isolation rates range from 1% to 19% (Haase et al, 1990;Bakare et al, 2003;Kondori et al, 2014;Kirchhoff et al, 2019). Ed can cause systemic infections (Kondori et al, 2014).…”

Fungal infection strategies

“…Another interesting feature of Cryptococcus is the formation of giant yeast cells, termed Titan cells that due to their size cannot be phagocytosed, and are more resistant to stressors [16]. Further examples presented in this Special Focus issue of opportunistic environmental fungal pathogens which produce pigments are Exophiala dermatitidis, reviewed by Kirchhoff et al [17], and Coccidioides. E. dermatitidis is a black yeast, a term originating from the dark pigmentation of this group of fungi.…”