Agar disk diffusion susceptibility tests with cilofungin (LY 121019)

Cilofungin (LY 121019) is a semi-biosynthetic lipopeptide agent which is active both in vitro and in vivo against isolates of Candida species. The purpose of this study was to demonstrate the usefulness of experimental 10- and 20-micrograms cilofungin disks in predicting probable in vitro susceptibility to this drug. Fifty-two isolates of pathogenic yeasts, which included 34 isolates of Candida albicans, 10 isolates of Candida tropicalis and eight isolates of Candida glabrata, were tested. Both agar dilution minimal inhibitory concentration (MIC) tests and matched agar disk diffusion tests were performed using 14-h-old broth cultures grown in single strength yeast nitrogen base (YNB) supplemented with asparagine and dextrose. Both tests were incubated at 35 degrees C and the results were read after 24 h. Regression analysis was used to measure the degree of correlation between MIC values and matched averaged zones of inhibition, and demonstrated that both the 10-micrograms (r = 0.9278) and 20-micrograms (r = 0.9082) disks can predict probable MIC values.