Development and Validation of AurisC2-ID, a Fourier-Transform Infrared Spectroscopy Classifier for Differentiation of Clade II and Non-Clade II Candida auris Isolates.

Candida auris clade II isolates are generally more susceptible to antifungal agents and are less frequently associated with outbreaks than non-clade II isolates. We developed and validated a Fourier-transform infrared (FTIR) spectroscopy-based classifier (AurisC2-ID) to distinguish clade II from non-clade II C. auris isolates. In total, 106 C. auris isolates col-lected from 14 Korean hospitals, representing clades I and II, and 10 reference isolates from the Centers for Disease Control and Prevention and Food and Drug Administration Antimicrobial Resistance Isolate Bank, representing four clades (I-IV), were analyzed using FTIR spectroscopy (IR Biotyper; Bruker Daltonics, Bremen, Germany) as the training set for classifier development. The classifier was constructed using an artificial neural network al-gorithm following principal component analysis and was validated using 87 additional clini-cal isolates collected from nine Korean hospitals. The training set spectra showed clear separation between clade II and non-clade II isolates, with minor overlap between the two groups. During validation, all 31 clade II isolates were correctly classified as clade II, and the remaining 56 clade I isolates as non-clade II. These results demonstrate that AurisC2-ID can accurately distinguish clade II from non-clade II C. auris isolates and may serve as a useful tool for infection control in Korea.