Multicenter Study of Epidemiological Cutoff Values and Detection of Resistance in Candida spp. to Anidulafungin, Caspofungin, and Micafungin Using the Sensititre YeastOne Colorimetric Method

Abstract

ABSTRACTNeither breakpoints (BPs) nor epidemiological cutoff values (ECVs) have been established forCandidaspp. with anidulafungin, caspofungin, and micafungin when using the Sensititre YeastOne (SYO) broth dilution colorimetric method. In addition, reference caspofungin MICs have so far proven to be unreliable.Candidaspecies wild-type (WT) MIC distributions (for microorganisms in a species/drug combination with no detectable phenotypic resistance) were established for 6,007Candida albicans, 186C. dubliniensis, 3,188C. glabratacomplex, 119C. guilliermondii, 493C. krusei, 205C. lusitaniae, 3,136C. parapsilosiscomplex, and 1,016C. tropicalisisolates. SYO MIC data gathered from 38 laboratories in Australia, Canada, Europe, Mexico, New Zealand, South Africa, and the United States were pooled to statistically define SYO ECVs. ECVs for anidulafungin, caspofungin, and micafungin encompassing ≥97.5% of the statistically modeled population were, respectively, 0.12, 0.25, and 0.06 μg/ml forC. albicans, 0.12, 0.25, and 0.03 μg/ml forC. glabratacomplex, 4, 2, and 4 μg/ml forC. parapsilosiscomplex, 0.5, 0.25, and 0.06 μg/ml forC. tropicalis, 0.25, 1, and 0.25 μg/ml forC. krusei, 0.25, 1, and 0.12 μg/ml forC. lusitaniae, 4, 2, and 2 μg/ml forC. guilliermondii, and 0.25, 0.25, and 0.12 μg/ml forC. dubliniensis. Species-specific SYO ECVs for anidulafungin, caspofungin, and micafungin correctly classified 72 (88.9%), 74 (91.4%), 76 (93.8%), respectively, of 81Candidaisolates with identifiedfksmutations. SYO ECVs may aid in detecting non-WT isolates with reduced susceptibility to anidulafungin, micafungin, and especially caspofungin, since testing the susceptibilities ofCandidaspp. to caspofungin by reference methodologies is not recommended.