The Fungistatic and Fungicidal Effects of the Fatty Acids on Species of Trichophyton *

During World War II, the number of infections caused by the dermatophytes reached alarming heights in the armed forces. This fact stimulated the search for agents that could not only inhibit the fungi but also kill them. Therefore, in investigating chemotherapeutic agents, both fungistatic and fungicidal activity must be examined, and to accomplish this, standard in vitro methods must be employed that eliminate as many variables as possible. Species and strains must be examined to ascertain if the difference in susceptibility to the agent precludes the use of a single species or strain of standard resistance for the test organism. The present studies represent an attempt to devise satisfactory methods for fungistatic and fungicidal tests, using the fatty acids as the anti-fungal agent, and to study the relative susceptibilities of several species and strains of fungi to these agents. Peck and Rosenfeld29 demonstrated the fungistatic action of various fatty acids against Trichophyton gypseum. Keeney and Brayles'8 investigated the fungistatic and fungicidal action of sodium propionate and pointed out that this salt was fungistatic for both Trichophyton gypseum and Trichophyton purpureum, although at different concentrations, but fungicidal for Trichophyton purpureum alone. In 1941, Cowles' had demonstrated that as the pH was lowered increased bactericidal action was exhibited by the fatty acids, and that at any fixed pH level the effective concentrations of the series varied according to Traube's rule. Kirby et al.23 concluded that the disinfecting property of acetic acid against molds was a function of pH. To see if the observations of Cowles held true for the dermatophytes a number of experiments were undertaken. The fungistatic and fungicidal action of the series of fatty acids from formic acid to caprylic acid in the saturated series was investigated originally, pelargonic acid