Biocide, antifungal susceptibility and virulence characteristics of Clade 1 Candidozyma auris strains

(1) Background: Candidozyma (Candida) auris is an emerging antifungal-resistant pathogen responsible for healthcare-associated infections. Beyond antifungal resistance, it can also resist hospital-use biocides. This study evaluated the virulence traits and antimicrobial susceptibility of C. auris isolates characterized both phenotypically and genotypically. (2) Methods: A total of 47 C. auris isolates, including the reference strain CDC B11903, were analyzed. ITS region sequencing was performed using Oxford Nanopore technology. Susceptibility to amphotericin B, fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, and isavuconazole was assessed using the CLSI microdilution method. Biocides tested were benzalkonium chloride (BZC), chlorhexidine (CHX), triclosan (TRC), and sodium hypochlorite (SHC). Virulence factors included biofilm, SAP, caseinase, phospholipase, esterase, and hemolytic activity. (3) Results: All isolates were identified as Clade 1. MIC50/90 values ranged from 0.12–32 µg/mL for antifungals and 0.01–16 mg/L for biocides. Fluconazole resistance was found in 31% of isolates, amphotericin B in 4%, and no echinocandin resistance. All strains showed biofilm and SAP activity; most were esterase positive, few expressed caseinase, and all exhibited alpha hemolysis. Notable correlations included amphotericin B with isavuconazole and TRC MICs, and with caseinase activity (ρ ≈ 0.31–0.35), suggesting potential cross-resistance and virulence links. (4) Conclusions: This is the first study from Türkiye comparing antifungal and biocide susceptibility with virulence profiles in Clade 1 C. auris . These findings support further research into resistance mechanisms and clinical impact.