Evaluation of a custom Sensititre YeastOne plate for susceptibility testing of isavuconazole and other antifungals against clinically relevant yeast and mould species in three Australian diagnostic mycology laboratories

Abstract

This study aimed to validate the performance of the custom formulated Sensititre YeastOne One (SYO) microdilution plate which includes isavuconazole (AUSNMRC1) to perform susceptibility testing on clinically relevant yeast and mould species across three Australian reference laboratories. The minimum inhibitory concentration (MIC) results were compared with the IVD approved SYO YO10 microdilution plate and isavuconazole gradient strips. A total of 127 isolates were tested on both the YO10 and AUSNMRC1 plates. The overall essential agreement (EA) and categorical agreement (CA) for the eight common drugs was 99.9% and 98.8%, respectively. The EA was 96.9% for the isavuconazole MICs obtained using the AUSNMRC1 plate and gradient strip. The MIC results for all nine antifungals on the AUSNMRC1 panel were highly reproducible for all quality control and reference strains and the overall EA and CA for 45 clinical strains tested across all three participating laboratories were >93% and 94.1%, respectively. These findings demonstrate the SYO AUSNMRC1 plate provides a commercial means to determine isavuconazole MICs by broth microdilution testing.

Keywords: Sensititre YeastOne microdilution; antifungal susceptibility testing; isavuconazole.