Yeasts of the genusPityrosporumin the mammalian external auditory canal with special reference to the dog

Abstract

Extract The genus Pityrosporum (Lodder and Kreger van Rij, 1952 Lodder, J. and Kreger van Rij, N. J. W. 1952. The Yeasts, A Taxonomic Study Amsterdam 1952 [Google Scholar] ) includes yeasts which reproduce by budding on a broad base and do not produce mycelium or pseudomycelium. They .have no fermentative ability and grow very slowly on malt agar. Some species such as P. ovale, the type species of the genus, require oleic acid or some fatty substance for growth. Gustafson ( 1955 Gustafson, B. A. 1955. Otitis Externa in the Dog. Stockholm 1955 [Google Scholar] ) has suggested that the genus should include a non-lipophilic yeast isolated from the ears of dogs with otitis externa. This organism has been provisionally named Pityrosporum canis and can be briefly described as an ascosporogenous yeast reproducing by budding on a broad case. Most of the cells are oval, no mycelium or pseudomycelium is formed, and fermentative ability is absent. From a number of experiments involving the introduction of P. canis into the ears of normal dogs, Gustafson concludes that it can be a cause of otitis externa.