Trichophytin contact sensitivity in patients with dermatophytosis.

Trichophytin contact sensitivity was investigated in patients with dermatophytosis by patch testing with highly concentrated purified trichophytin on partially stripped skin. The lack of primary irritant reactions was confirmed on the skin of children. Positive patch tests were noted in 113 of 178 patients (63.5%). However, there was a great difference in the incidence of trichophytin contact sensitivity between cases with different clinical types. The highest frequency of positive patch tests was obtained in patients with the vesiculobullous type of tinea pedis (83.3%). In contrast, a very low incidence was noted in patients with tinea corporis (37%) and the squamous hyperkeratotic type of tinea pedis (36%). Causative organisms and the age and sex of the patients did not show a relationship with the reactivity. A diminished incidence of positive reactions was noted in atopic individuals and in patients seen in winter. Patients who had persistent or recurrent infections for a long period of time, especially those having inflammatory lesions, had a higher frequency of positive patch tests.