Field Evaluation of the ClaID PCR System Reveals Predominance of Clade I-Associated Molecular Profiles Among Clinical Candida auris Isolates Recovered in İstanbul, Türkiye

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Background: Candida auris has emerged globally as a multidrug-resistant fungal pathogen responsible for healthcare-associated outbreaks and invasive infections. Whole-genome sequencing studies have demonstrated the existence of genetically distinct clades that differ in geographical distribution, antifungal resistance patterns, virulence traits, and outbreak potential. Objectives: This study aimed to evaluate the performance of the ClaID clade identification PCR system among clinical Candida auris isolates collected in İstanbul, Türkiye, and to investigate the clade-associated molecular profiles of circulating isolates. Methods: Forty-four clinical C. auris isolates were analysed using the auris universal sequence (AUS) assay and clade-specific sequence assays (CSS1–CSS5). PCR amplification results were interpreted according to the ClaID framework. Results: AUS amplification was detected in 41/44 isolates (93.2%). CSS1 amplification was observed in 39/44 isolates (88.6%), indicating a predominance of Clade I-associated molecular profiles within this regional İstanbul isolate collection. No amplification was detected using CSS2, CSS3, CSS4, or CSS5 assays. Three isolates were AUS-negative and five isolates did not yield CSS1 amplification despite repeated testing. Conclusions: The findings suggest that the majority of analyzed clinical isolates from İstanbul exhibited Clade I-associated molecular profiles rather than definitive WGS-confirmed clade assignments. This study provides one of the first field evaluations of the ClaID system in a Turkish clinical isolate collection and contributes regional molecular epidemiological data regarding PCR-based clade-associated profiles of C. auris in Türkiye.