Widespread tinea corporis caused by Trichophyton rubrum with non-typical cultural characteristics--diagnosis via PCR.

From the epidemiological point of view, Trichophyton rubrum is the most important dermatophyte in the Western world. Mostly, the lesions of fungal infections of the skin are restricted and circumscribed. Immunodeficiency, diabetes or treatment with steroids, however, favour widespread disease involving the entire integument. In the present study, we describe a patient without immunodeficiency or diabetes presenting with widespread tinea corporis caused by T. rubrum. The fungal isolate showed atypical morphological features. Moreover, the typical metabolic features (negative urease test, production of red pigment on potato dextrose agar) were expressed with delay after 6 weeks of cultivation. Thus, sequencing of the internal transcribed spacer of the ribosomal DNA was applied to identify the fungal isolate and led us to the correct diagnosis, before conventional mycological methods were successful.