Background: Although the role of inhaled fungi in inducing asthma has been repeatedly confirmed, there are few reports about the association of asthma with dermatophyte sensitivity and the causal role of Trichophyton allergy in asthma. The objective was to investigate the presence of Trichophyton sensitivity among patients with allergic and nonallergic asthma in combination with tinea, and to compare the situation with several control groups in order to evaluate the factors determining Trichophyton sensitivity.
Methods: A total of 86 subjects (55 female, 31 male) with a mean age of 38.6 +/- 11.1 years were included in the study. The patients were divided into five groups: 1) nonallergic asthma plus tinea (n = 19) 2) allergic asthma plus tinea (n = 15) 3) asthma without tinea (n = 22) 4) tinea without asthma (n = 17) 5) healthy controls (n = 13). Skin tests with standardized extracts of T. rubrum and specific IgE measurements were performed in all subjects. All patients were also subjected to microscopic evaluation and fungal culture for dermatophyte infection.
Results: The skin test positivity rate to Trichophyton extract of groups 1 (63.1%), 2 (46.7%), and 4 (47.1%) was higher than that in groups 3 (4.4%) and 5 (7.7%) (P < 0.05). Although not significant, the rates of sensitivity to T. rubrum (63.1%) and of severe asthma (31.6%) were higher in the group with nonallergic asthma with tinea (group 1) than in other groups. Among 51 patients in whom direct microscopic evaluation revealed dermatophyte infection, 60.8% had positive fungal cultures for T. rubrum (58.1%), T. mentagrophytes (35.5%), and Candida (6.4%).
Conclusion: According to our data, the presence of fungal infection seems to be an important determinant in hypersensitivity to Trichophyton whether or not the subject is asthmatic and/or allergic. Since a greater proportion of patients with nonallergic asthma--in whom the rate of severe asthma was also higher - showed positive skin tests to Trichophyton extracts in this study, we believe that patients with severe, intrinsic asthma should be examined for signs of fungal infection and tested to determine immediate hypersensitivity to dermatophyte antigens.