Multilaboratory Study of Epidemiological Cutoff Values for Detection of Resistance in Eight Candida Species to Fluconazole, Posaconazole, and Voriconazole

Abstract

ABSTRACTAlthough epidemiological cutoff values (ECVs) have been established forCandidaspp. and the triazoles, they are based on MIC data from a single laboratory. We have established ECVs for eightCandidaspecies and fluconazole, posaconazole, and voriconazole based on wild-type (WT) MIC distributions for isolates ofC. albicans(n= 11,241 isolates),C. glabrata(7,538),C. parapsilosis(6,023),C. tropicalis(3,748),C. krusei(1,073),C. lusitaniae(574),C. guilliermondii(373), andC. dubliniensis(162). The 24-h CLSI broth microdilution MICs were collated from multiple laboratories (in Canada, Brazil, Europe, Mexico, Peru, and the United States). The ECVs for distributions originating from ≥6 laboratories, which included ≥95% of the modeled WT population, for fluconazole, posaconazole, and voriconazole were, respectively, 0.5, 0.06 and 0.03 μg/ml forC. albicans, 0.5, 0.25, and 0.03 μg/ml forC. dubliniensis, 8, 1, and 0.25 μg/ml forC. glabrata, 8, 0.5, and 0.12 μg/ml forC. guilliermondii, 32, 0.5, and 0.25 μg/ml forC. krusei, 1, 0.06, and 0.06 μg/ml forC. lusitaniae, 1, 0.25, and 0.03 μg/ml forC. parapsilosis, and 1, 0.12, and 0.06 μg/ml forC. tropicalis. The low number of MICs (<100) for other less prevalent species (C. famata,C. kefyr,C. orthopsilosis,C. rugosa) precluded ECV definition, but their MIC distributions are documented. Evaluation of our ECVs for some species/agent combinations using published individual MICs for 136 isolates (harboring mutations in or upregulation ofERG11,MDR1,CDR1, orCDR2) and 64 WT isolates indicated that our ECVs may be useful in distinguishing WT from non-WT isolates.