Update on clinical antifungal susceptibility testing for Candida species

With the emergence of fungi as important nosocomial pathogens, increasing reports of antifungal resistance, and expanding drug therapy options, the need for clinically relevant antifungal susceptibility testing is evident. Over the last decade, the National Committee for Clinical Laboratory Standards (NCCLS) worked to standardize procedures for in vitro susceptibility testing of Candida species against fluconazole, itraconazole, 5-fluorocytosine, and amphotericin B. With the establishment of a reproducible methodology, correlation of antifungal susceptibility in vitro with clinical outcome is a priority. The NCCLS proposed susceptibility breakpoints for the three agents against Candida species, with breakpoints for amphotericin B forthcoming. These breakpoints could provide useful guidance in some clinical situations involving azole or 5-fluorocytosine therapy; however, routine susceptibility testing of fungal isolates should be discouraged.