[Experimental dermatitis caused by Pityrosporum ovale and (or) Pityrosporum orbiculare in the guinea pig and the mouse].

An experimental dermatitis was established for the guinea pig and Swiss white mouse by topical application of cultures of Pityrosporum ovale, isolated from pityriasis capitis and from P. arbiculare isolated from pityriasis versicolor. Histology showed the development of the yeasts in the stratum corneum, with hyperkeratosis at the follicular ostium and in the pilous bulb: the clinical and histological appearances resembled human seborrheic dermatitis. The nude (nu/nu) mouse, the hair-less mouse and the nude rat were not susceptible to this experimental infection, probably because of the dystrophy of their pilous follicles and sebaceous glands. The experimental model permitted evaluation of antifungal agents. The Pityrosporum dermatitis disappeared rapidly after topical application of econazole or amphotericin B. No pathological differences were observed between the strains tested.