Susceptibility testing of the echinocandins against Candida species in the daily routine: ETest(R) versus Sensititre YeastOne(R). Data from a single center in Austria [PublishAheadOfPrint]

Antifungal susceptibility testing of caspofungin, anidulafungin and micafungin against Candida species was performed to evaluate the role of ETest® and Sensititre YeastOne® for antifungal susceptibility testing for daily routine and to survey resistance. 104 Candida species isolates detected from blood cultures were investigated. Determining EUCAST broth microdilution as reference method essential agreement (EA), categorical agreement (CA), very major errors (VME), major (ME) and minor errors (MIN) were assessed reading MICs at 18, 24 and 48 hours. Applying EUCAST broth microdilution and species-specific clinical breakpoints (cbps) echinocandin resistance was not detected during the study period. Applying EUCAST cbps MIC reading at 24 hours for ETest® and Sensititre YeastOne® resulted in a CA of 99% and 93% for anidulafungin and 99% and 97% for micafungin. Applying revised CLSI cbps for caspofungin CA was 92% and 99% for the ETest® and Sensititre YeastOne®. The ETest® proved to serve as an excellent easy-to-handle alternative method for antifungal susceptibility testing of anidulafungin and micafungin. Due to misclassifications the ETest® is less suitable for susceptibility testing of caspofungin (8% falsely resistant). CA for the Sensititre YeastOne® was 93% and 97% for anidulafungin and micafungin (24 hours) applying EUCAST cbps and increased up to 100% each if CLSI cbps versus 100% and 99% if Sensititre YeastOne® epidemiological cutoff values (ECOFFs) applied. In vitro superiority of one or another echinocandin could not be demonstrated. As resistance was lacking among our Candida isolates, we cannot derive any recommendation from accurate resistance detection of ETest® and Sensititre YeastOne®.

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