Head-to-head comparison of CLSI, EUCAST, Etest and VITEK®2 results for Candida auris susceptibility testing

The susceptibility of 31 Candida auris clinical isolates was evaluated by four methods, namely the microdilution reference method according to Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines as well as Etest and VITEK (R) 2. Essential agreement between the two reference methods was 90%. Etest showed a better overall agreement with the reference methods (94% and 81% for CLSI and EUCAST, respectively) than VITEK (R) 2 (70% and 72%, respectively). Discrepancies were found for fluconazole (FLC) and amphotericin B. Considering categorical agreement (CDC tentative breakpoints), the majority of isolates were considered FLC-resistant (93.6% and 80.6% by CLSI and EUCAST, respectively). Furthermore, all isolates were considered susceptible to echinocandins by all methods. Susceptibility results should be interpreted with care if the VITEK (R) 2 system is used to guide therapeutic decisions for C. auris infections. (c) 2022 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.

Automated summary

The susceptibility of 31 Candida auris clinical isolates was evaluated using four different methods. The results showed that Etest had a higher agreement with the reference methods compared to VITEK (R) 2. Discrepancies were observed for fluconazole and amphotericin B. Most isolates were considered resistant to fluconazole based on categorical agreement. All isolates were susceptible to echinocandins. Caution should be exercised when interpreting susceptibility results using the VITEK (R) 2 system for C. auris infections.