Experimental dermatophyte infection. The extent of the fungal invasion

A spore suspension from a granular strain of Trichophyton mentagrophytes under occlusion for 4 days was used to produce two fungal lesions on the upper arm of the Trichophytin-negative author. The material for culture was obtained by stripping across the visible lesions and several centimetres into the surrounding skin. Already when the occlusion was removed, the whole stratum corneum was heavily invaded up to 20 mm into the surrounding, normal-looking skin. When the intensity and the size of the visible lesions topped after about 2 weeks, the culture positivity reached 45 mm into the perilesional skin. One week later the spontaneous involution had eliminated nearly all fungal organisms through the entire horny layer of both the visible lesions and their surroundings. After 42 days the lesions were culture-negative. It was concluded that the growth pattern of an experimental infection could be as observed in natural infections.