Mycological Aspects of Action of Griseofulvin Against Dermatophytes

Introduction The discovery of griseofulvin, the first systemic substance active against the septate fungi causing dermatophytic conditions in man and animals, raises the question whether resistant forms of these fungi will appear as a result of its continued chemotherapeutic use. It is of prime interest to have some guidance on how readily, if at all, dermatophytes can develop tolerance to griseofulvin under natural conditions. While this answer must ultimately be derived from clinical experience, it seemed important to learn as much as possible about the development of resistance in vitro. While the majority of this work was carried out using Microsporum canis, Trichophyton rubrum strains were also examined. Material and Methods Six strains of Microsporum canis and three of Trichophyton rubrum were obtained from various sources. Details of their nomenclature and characteristics are given in Table 1. These strains were maintained on a Sabouraud-Malt agar medium having the following composition: