Comparative evaluation of National Committee for Clinical Laboratory Standards broth macrodilution and agar dilution screening methods for testing fluconazole susceptibility of Cryptococcus neoformans

William R. Kirkpatrick, Robert K. Mcatee, Sanjay G. Revankar, Annette W. Fothergill, Dora I. Mccarthy, Michael G. Rinaldi, Thomas F. Patterson

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Abstract

A simple screening method for fluconazole susceptibility of Cryptococcus neoformans using 2% dextrose Sabouraud dextrose agar (SabDex) with fluconazole was compared to the National Committee for Clinical Laboratory Standards (NCCLS) broth macrodilution method. By this method, a fluconazole-susceptible C. neoformans isolates are significantly smaller on medium with fluconazole than on fluconazole-free medium. Isolates with decreased susceptibility have normal-size colonies on medium containing fluconazole. The 48-h NCCLS broth macrodilution MICs (NCCLS MICs) for isolates with normal-size colonies on 8- or 16-μg/ml fluconazole plates were predicted to be ≤16 μg/ml, respectively. On medium with 16 μg of fluconazole per ml, all strains (84 of 84) for which the NCCLS MICs were <16 μg/ml were correctly predicted, as were all isolates (7 of 7) for which the MICs were ≤16 μg/ml. Agar dilution appears to be an effective screening method for fluconazole resistance in C. neoformans.

Original languageEnglish (US)
Pages (from-to)1330-1332
Number of pages3
JournalJournal of clinical microbiology
Volume36
Issue number5
StatePublished - May 1 1998

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ASJC Scopus subject areas

  • Microbiology (medical)

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