activity of isavuconazole, ravuconazole, and comparison of the Sensititre YeastOne and CLSI broth microdilution methods against clinical isolates of species.

This study aimed to evaluate the activity of isavuconazole and ravuconazole against clinical isolates. Additionally, we assessed the performance of the Sensititre YeastOne (SYO) assay compared to the reference Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) method for antifungal susceptibility testing. A total of 267 clinical isolates were collected from multiple centers in Taiwan between 2008 and 2020. The MIC values for amphotericin B, fluconazole, itraconazole, posaconazole, and voriconazole obtained using the CLSI BMD were compared to those determined using SYO. Among the seven antifungal agents tested using the CLSI BMD method, isolates ( = 224) exhibited significantly higher MICs for fluconazole, voriconazole, isavuconazole, and ravuconazole compared to non-. isolates ( = 43) ( < 0.05). Across all isolates, voriconazole demonstrated the lowest geometric mean (GM) MIC (0.06 mg/L). For , the MIC₅₀, MIC₉₀, and GM MICs for posaconazole, isavuconazole, and ravuconazole were within ±1 twofold dilution, while mode MICs showed slightly greater variation (MIC₅₀, MIC₉₀, mode, and GM MICs were 0.25, 0.5, 0.5, and 0.28 mg/L; 0.12, 0.5, 0.12, and 0.17 mg/L; and 0.25, 0.5, 0.25, and 0.21 mg/L, respectively). The consistency of the MIC measurements between the SYO and CLSI BMD methods was assessed for amphotericin B, fluconazole, itraconazole, posaconazole, and voriconazole. The highest agreement within ±1 twofold dilution for isolates was observed for posaconazole (94.2%). The essential agreement within ±2 twofold dilutions between both methods for all drugs was >97%. In conclusion, isavuconazole and ravuconazole demonstrated favorable activity against clinical isolates, while the SYO assay showed good concordance with the CLSI BMD method.IMPORTANCEInvasive infections caused by species pose significant therapeutic challenges, primarily due to their intrinsic resistance to echinocandins and the limited availability of effective treatment options. This study provides essential data on the activity of newer azoles and comprehensively evaluates the performance and concordance of the Sensititre YeastOne (SYO) and CLSI broth microdilution (BMD) methods. The current study analyzed 267 clinical isolates collected from multicenter settings in Taiwan. Our results demonstrate that both isavuconazole and ravuconazole exhibit favorable activities against species. For , the essential agreement between the SYO and CLSI BMD methods exceeded 97% for all tested antifungal agents, indicating that the SYO method exhibits good concordance for most species. Further investigations are warranted to validate these findings and to assess their clinical implications.