FLUCONAZOLE AND AMPHOTERICIN-B ANTIFUNGAL SUSCEPTIBILITY TESTING BY NATIONAL COMMITTEE FOR CLINICAL LABORATORY STANDARDS BROTH MACRODILUTION METHOD COMPARED WITH E-TEST AND SEMIAUTOMATED BROTH MICRODILUTION TEST

A comparative study of fluconazole and amphotericin B susceptibility t esting was performed with 68 clinical Candida species isolates and thr ee test methods, The methods used were an agar diffusion method (E-tes t) and two broth dilution methods, the National Committee for Clinical Laboratory Standards (NCCLS) reference broth macrodilution method and an in-house-prepared semiautomated broth microdilution method based o n the Bioscreen turbidometer. In the microdilution method, growth of t he yeasts was measured continuously by the automatic turbidometer (Bio screen), which permitted precise and objective determination of endpoi nts, MIC endpoints were read after 24 h for the microdilution method a nd the E-test, Amphotericin B susceptibility testing with the NCCLS me thod and the E-test yielded comparable results in 89% of the tests, me aning that the endpoints obtained were identical or differed by no mor e than 2 twofold dilutions, The NCCLS and broth microdilution tests sc ored 97% comparable results, and the E-test and the broth microdilutio n test yielded 90% comparable results, Fluconazole susceptibility test ing produced 96% comparable results with the NCCLS test and the E-test , 100% comparable results with the NCCLS and the microdilution methods , and 98.5% comparable results with the microdilution method and the E -test, We conclude that the E-test and the Bioscreen microdilution met hod are valuable alternatives to the NCCLS reference method for routin e susceptibility testing of Candida species with fluconazole and ampho tericin B.