Experimental dermatophytosis: the clinical and histopathologic features of a mouse model using Trichophyton quinckeanum (mouse favus)

We have established a reproducible mouse model of dermatophytosis using Trichophyton quinckeanum. There was considerable variation in the pathogenic potential among 10 different strains of T. mentagrophytes or T. quinckeanum; susceptibility to the infection varied with the inbred strain of mouse used, with BALB/c or BALB/K mice proving to be the most susceptible. The primary infection was characterized by the development of a scutulum or crust consisting of large quantities of dermatophyte mycelium, dense infiltration with neutrophils, but minimal epidermal proliferation. By contrast, a secondary infection initiated 30 days after the primary infection showed different features with early and almost total elimination of fungal elements, a predominantly mononuclear cell response, and epidermal proliferation. If the secondary infection was given at the peak of the primary illness (day 7), there was a mononuclear cell response with epidermal proliferation but fungal mycelium was prominent and not quickly eliminated. The value of this model in investigating the kinetics of the immune response to experimental dermatophytosis is discussed.