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Trichosporon isolation from human ungueal infections: is there a pathogenic role?* * Work performed at the Laboratório de Micologia Médica e Molecular - Departamento de Microbiologia e Parasitologia do Instituto Biomédico - Universidade Federal Fluminense (UFF) – Niterói (RJ), Brasil.

Abstract

BACKGROUND:

Although dermatophytes are considered the major cause of onychomycosis, many reports have incriminated non-dermatophyte moulds and yeasts in the disease’s etiology. Successive Trichosporon isolation from onychomycosis has led to the genus being suspected as a nail primary pathogen.

OBJECTIVE:

To determine the prevalence of Trichosporon isolation in onychomycosis patients who attended a mycology diagnostic service in Rio de Janeiro, Brazil, between January 2003 and December 2006. The study also includes a worldwide review on Trichosporon isolation prevalence in ungueal disease, emphasizing T. ovoides.

METHODS:

This retrospective study was conducted with the support of staff from the Mycology Laboratory at the Dermatological Service of Rio de Janeiro’s Santa Casa da Misericórdia (MLDS).

RESULTS:

Mycological analysis provided positive results equaling 47/5036 (0.93%) for Trichosporon spp.; obtained mainly as a single agent (72.35%), and from mixed cultures (27.65%; X2= 6.397; p= 0.018). The great majority belongs to the T. ovoides species (91.5%; n=43), obtained as a single isolate (74.41%; n= 32/43; X2 = 7.023; p= 0.014).

CONCLUSIONS:

Although T. ovoides is classically associated as an etiologic agent of white piedra, this study highlights its potential as a human nail disease pathogen. Our study opens doors for future epidemiologic and virulence factors aimed at determining whether T. ovoides is an important causative agent of onychomycosis in Brazil.

Keywords:
Diagnosis; Nail diseases; Trichosporon; Trichosporonosis

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