Experimental Infections in Rabbits and Humans with Pityrosporum orbiculare and P. ovale

Abstract

The purpose of this investigation was to produce experimental tinea versicolor in rabbits and humans with Pityrosporum orbiculare and P. ovale. P. orbiculare and P. ovale were inoculated, with and without occlusion, on the inside of the ear in 10 male rabbits and on the upper arm in 10 patients with a history of tinea versicolor, and in 3 healthy volunteers. After 1 week tinea versicolor-like lesions were produced with both P. orbiculare and P. ovale in 8 of 10 rabbits. Likewise experimental infections, similar to those found clinically in tinea versicolor, were seen, after 1 week, in 5 patients with a history of tinea versicolor and in the 3 healthy volunteers. Two of 5 patients inoculated for only 4 days showed identical but less pronounced lesions. Experimental infections could only be produced with occlusion. Microscopically short hyphae and transformation between round and oval forms were seen in both P. orbiculare and P. ovale. This investigation adds to the identity of P. orbiculare and P. ovale and also to the identity of these 2 fungi and the fungus seen in tinea versicolor. Spontaneous healing and the fact that experimental infections were produced only under occlusion illustrates the importance of predisposing factors in tinea versicolor.

Atopic Dermatitis and Fungi

“…The name he gave the organism, P. orbicualre, is based primarily on the micromorphology. However, later studies have shown that the round and oval forms of the organism are not stable (12) and that the two forms can change from one to the other on special culture media or under special culture condi-tions (128) and when experimental infections are induced in rabbits (34).…”

In vitro and in vivo activities of ketoconazole and itraconazole against Pityrosporum orbiculare

“…Experimental pityriasis (tinea) versicolor-like lesions have been produced with Pityrosporum orbiculare (P. ovale) under plastic occlusion in both rabbits and humans (1,5). A method for the in vitro estimation of the MICs of potential therapeutic agents against P. orbiculare (P. ovale) has also been described (2,4).…”

“…The details of the experimental infections have been described previously (1,5). P. orbiculare ATCC 44031 was used.…”

Tinea Versicolor in the Eastern Province of Saudi Arabia

“…4 In the past, all were thought to be distinct fungi, but recent evidence suggests the three are variants of each other. 5,6 Tinea versicolor has a higher incidence in tropical climates and during warmer months in temperate climates than is seen in cooler environments.…”