Spectrum of Clinically RelevantExophialaSpecies in the United States

Abstract

Numerous members of the genus Exophiala are potential agents of human and animal mycoses. The majority of these infections are cutaneous and superficial, but also fatal systemic infections are known. We re-identified 188 clinical isolates from the United States, which had a preliminary morphological identification of Exophiala species, by sequencing internal transcribed spacer (ITS) region of the rRNA. Molecular identifications of the strains were as follows, in order of frequency: 55 E. dermatitidis (29.3%), 37 E. xenobiotica (19.7%), 35 E. oligosperma (18.6%), 13 E. lecanii-corni (6.9%), 12 E. phaeomuriformis (6.4%), 7 E. jeanselmei (3.7%), 7 E. bergeri (3.7%), 6 E. mesophila (3.2%), 5 E. spinifera (2.7%), 3 Exophiala sp. 1 (1.6%), 3 E. attenuata (1.6%), 3 Phialophora europaea (1.3%), 1 E. heteromorpha (0.5%), and 1 Exophiala sp. 2 (0.5%) strains. Exophiala strains were repeatedly isolated from deep infections (39.9%) involving lung, pleural fluid, sputum, digestive organs (stomach, intestines, bile), heart, brain, spleen, bone marrow, blood, dialysis fluid, lymph node, joint, breast, middle ear, throat, and intraocular tissues. About 38.3% of the Exophiala spp. strains were agents of cutaneous infections including skin, mucous membranes, nail, and corneal epithelium lesions. The other strains caused superficial infections (0.5%, including hair) or subcutaneous infection (12.0%, including paranasal sinusitis, mycetoma, and subcutaneous cyst). The systemic infections were preponderantly caused by E. dermatitidis, E. oligosperma, E. phaeomuriformis, E. xenobiotica, and E. lecanii-corni. Strains of E. bergeri, E. spinifera, E. jeanselmei, E. mesophila, and E. attenuata mainly induced cutaneous and subcutaneous infections. Since relatively few unknown ITS motifs were encountered, we suppose that the list of opportunistic Exophiala species in temperate climates is nearing completion, but a number of species still have to be described.

New and interesting chaetothyrialean fungi from Spain

“…For molecular species identification, percent identities of just the ITS locus were considered, because it offers a higher resolution than the relatively conserved LSU gene (Iwen et al 2002). If the identity of the ITS sequence of a studied strain to its closest match was ≥99 %, they were considered conspecific (Zeng et al 2007). In rare cases where more than one species yielded 99 % identity, but none of them reached 100 %, the studied strain was identified only to genus level.…”

Phaeohyphomycotic cyst in the Foot by Exophiala

“…Around 30 different species of this genus have been isolated from different environmental sources of tropical and subtropical regions [2]. These fungi are known to cause systemic as well as subcutaneous cystic lesions [3]. The genus Exophiala found in the environment is known to cause subcutaneous cystic infection in immunocompetent as well as the immunosuppressed individual [4].…”

A Case of Phaeohyphomycosis Caused by Exophiala oligosperma in a Renal Transplant Patient Successfully Treated with Posaconazole

“…E. jeanselmei is the most frequently cited of the Exophiala species as a human pathogen, however sequence data has subsequently shown that E. jeanselmei is a species complex and that many of these case reports would represent other species if characterized at the molecular level. The most common clinically relevant species in the United States is E. dermatitidis (Zeng et al, 2007). Other species such as E. moniliae, E. oligosperma and E. spinifera have been implicated as well (Zeng et al, 2007).…”