Key words: yeast, Etest(R), microdilution method, MIC

Table 1 MICs of quality control strains The data shown are the range of MIC performed in triplicate

Table 2 Renge of MICs, MIC50s and MIC90s for 81 species of yeast

Table 3 Comparison of E test MICs with FP panel MICs

Table 4 Test of significance to MICs by FP panel and E test *: <0.05 significant **: <0.01 significant

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Evaluation of a New Method for Antifungal Drugs Susceptibility Testing to Yeasts Shinobu ISHIGAKI1), Sayoko KAWAKAMI1), Yasuo ONO1)2)&Yukihisa MIYAZAWA1) Department of Central Laboratory, 2)Department of Microbiology and Immunology, Teikyo School of Medicine We compared the Etest(R) with a broth microdilution method (FP panel(r)), performed according to the National Committee for modified Clinical Laboratory Standards (NCCLS) document M27-P guidelines, for determining the MICs of 81 clinical isolates of yeasts (7 Candida albicans, 8 Candida glabrata, 10 Candida parapsilosis, 6 Pichia anomala, 10 Candida tropicalis, 4 Candida guilliermondii, 4 Candida krusei, 6 Trichosporon cutaneum, 5 Candida ciferrii, 3 Candida famata, 4 Candida norvegensis, 2 Rhodotorula rubra, 3 Candida lusitaniae, 2 Candida curvata, 1 Candida inconspicua, 1 Candida intermedia, 1 Candida colliculosa, 1 Cryptococcus spp, 1 Tricosporon capitatum, 1 Pichia ohmeri, 1 Saccharomyces cerevisiae). The Etest(R) results for 6 ATCC standard strains correlated well with reference MICs except those of flucytosine (5-FC) for C. krusei, which tended to be 1 to 2 log2 dilution higher than the MIC range determined by NCCLS guidelines. However, the best agreement between the results for clinical isolates was seen with 5-FC (100% agreement [Within }2 log2 dilutions] between the results of the two methods). There was a 91.4% agreement between the results of the two methods with amphotericin B (Etest(R) MICs tended to be 1 to 2 log2 dilution lower than those of the FP panel). The Etest(R) results with litraconazole for clinical isolates except C. tropicalis were similar to MICs of the FP panel(r) (Etest(R) for C. tropicalis showed 1 to 2 log2 dilution lower than FP panel(r)). Also, the Etest(R) results with fluconazole for clinical isolates except C. tropicalis were similar of 1 log2 dilution higher than MICs of the FP panel(r) (Etest(R) for C. tropicalis showed more than 2 log2 dilution lower thas FP panel(r)). These results showed a good level of overall agreement between the Etest(R) method and the broth microdilution test (FP panel(r)). Since the Etest(R) is a less laborintensive and much simpler method, it appears to be a useful procedure for testing the susceptibility of yeasts to antifungal agents.