Susceptibility of Cryptococcus neoformans by the NCCLS microdilution and Etest methods using five defined media.

The susceptibility of 12 isolates of Cryptococcus neoformans to amphotericin B, 5-fluorocytosine, fluconazole, itraconazole and ketoconazole was tested using the NCCLS and Etest methods with yeast nitrogen base (YNB) pH 5.6 and pH 7.0, RPMI MOPS pH 7.0 with and without added glucose (2%) and RPMI buffered with phosphate buffer to pH 7.0. Some isolates yielded poor growth in RPMI MOPS after 72 h. Tests indicated that YNB pH 5.6 was the best medium for 5-fluorocytosine but was unsuitable for ketoconazole. In conclusion, YNB pH 7.0 or RPMI MOPS with 2% glucose can be used with either method.