Activity of cilofungin (LY121019) against Candida species in vitro

Cilofungin (LY121019) was compared with amphotericin B in vitro for its inhibitory and fungicidal activity against Candida species. In minimal inhibitory concentration (MIC) tests the two compounds showed comparable inhibitory activity against 31 isolates of C. albicans and C. tropicalis. However, cilofungin was by comparison only weakly active against 19 isolates representing the species C. glabrata, C. kefyr and C. krusei, and essentially inactive against 11 isolates representing C. guilliermondii and C. parapsilosis. The inhibitory activity of cilofungin, unlike that of amphotericin B, was reduced in medium containing serum. Relative inhibition factors (RIFs) for the two compounds confirmed the MIC data: RIFs of 85% and more were obtained in tests with species other than C. albicans and C. tropicalis: for the latter two species, RIFs were in the range 41-66%, indicating drug activity comparable to that of systematically active azole compounds. (RIFs for amphotericin B were less than 40% for all isolates.) Cilofungin was generally less fungicidal than amphotericin B, and it was only rarely fungicidal in tests done in medium containing serum. Because of its inhibitory action and its low toxicity, the compound may prove to be therapeutically useful in infections caused by the two most commonly encountered pathogenic Candida species.