The protective effect of an interferon inducer with a low molecular weight, 9-methylstreptimidone (9-MS), against
Candida albicans
infection in mice was investigated. The antibiotic was effective only when given prophylactically. When administered in such a manner, the growth of
C. albicans
in the kidneys and brain was inhibited at the initial stage of infection. The growth of
C. albicans
was not inhibited by the antibiotic in vitro, and no antifungal effect was obtained in a preparation containing induced interferon. These results suggest that the antifungal action of 9-methylstreptimidone in mice might be manifested not by direct antifungal activity but rather by a host-mediated activity that excludes interferon-inducing capability.