Chlamydoconidium-producing Trichophyton tonsurans: Atypical morphological features of strains causing tinea capitis in Ceará, Brazil

Abstract

Objective: To report atypical morphological features of Trichophyton (T.) tonsurans strains associated with tinea capitis. Methods: Eighty-two T. tonsurans strains isolated in Ceará, Brazil, were analyzed regarding macro and micromorphological features and nutritional patterns. Results: Fifty-two samples presented abundant chlamydoconidia, which were produced in chains. Macroscopically, these strains developed small glabrous colonies that were firmly attached to the surface of the culture medium, with few or no aerial mycelia and intense rusty yellow pigmentation. Seven strains did not grow with stimulus from thiamine. Samples were heterogeneous regarding urease production and none presented in vitro hair perforation. Conclusions: The observation of T. tonsurans strains with distinct phenotypic features indicates the need to revise the taxonomic criteria for routine identification of this dermatophyte.

Keywords

• trichophyton tonsurans
• chlamydoconidia
• dermatophyte
• phenotyping