Serological differences among the dermatophytes.

Antigens were prepared from young mycelial growth of 20 species of dermatophytes, and tested by double diffusion against homologous and heterologous antisera raised in rabbits. 48 distinct antigens were recognised by the procedures used. Although there were a considerable number of common reactions, there were significant differences between species and groups. Species of Microsporum, with the exception of M. gypseum and M. persicolor, form a coherent group distinct from Epidermophyton and Trichophyton. All Trichophyton species investigated with the exception of T. ajelloi, were serologically closely related. M. gypseum, T. ajelloi and M. persicolor showed affinities with both Microsporum and Trichophyton, and possibly form an intermediate group. The system used does not permit differentiation of species by serological means, but gives a new dimension to the inter-relationships of these fungi.