Objective:

To characterize a large Candida auris candidemia outbreak at a tertiary care hospital in Adana, Türkiye, from April 2023 through September 2025 and to investigate its clinical features, antifungal resistance, transmission dynamics, and genetic relatedness.

Approach:

• Patient Inclusion and Isolate Collection: All patients with C. auris candidemia identified at Adana City Hospital between April 23, 2023, and September 26, 2025, were included. Blood cultures were processed using an automated system, and isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
• Antifungal Resistance Assessment: Antifungal susceptibility testing was performed by CLSI broth microdilution against 8 antifungal agents. Minimum inhibitory concentrations were determined, and hotspot region 1 of FKS1 was sequenced in isolates with elevated echinocandin MICs.
• Genotyping: Short tandem repeat genotyping was performed on all isolates using 12 microsatellite markers to assess genetic relatedness and compare outbreak isolates with previously genotyped C. auris strains.

Key Findings:

• A total of 119 patients developed C. auris candidemia during the study period, with a 30-day mortality rate of 53.8%.
• Cases initially occurred in burn center-associated wards and the medical oncology service, then increased and spread across multiple wards, particularly the medical ICU and anesthesia and reanimation ICU.
• All 119 isolates showed high fluconazole MICs and were classified as resistant; 2 isolates had elevated echinocandin MICs and harbored the FKS1 S639P substitution.
• Genotyping assigned all isolates to clade I and identified 3 closely related genotypes, supporting clonal spread across multiple wards.
• Epidemiological and genotyping data suggested that the outbreak originated from a single index patient and subsequently spread within the hospital without evidence of additional introductions.

Interpretation:

The findings indicate that C. auris became established within this tertiary care hospital through sustained nosocomial transmission of a closely related clade I strain. Universal fluconazole resistance and the emergence of echinocandin-resistant isolates further complicated management and highlighted the importance of antifungal stewardship, screening, surveillance, and infection prevention.

Limitations:

• The retrospective design limited the investigation, and screening of patients at nonsterile body sites and environmental sampling were not performed, leaving the full extent of C. auris dissemination within the hospital unknown.
• Whole-genome sequencing was not performed, preventing determination of whether the 2 echinocandin-resistant isolates developed resistance independently during therapy or whether a resistant strain emerged once and was subsequently transmitted.
• Because environmental sampling was not conducted, the precise mode of transmission within the healthcare center remained speculative.

Conclusion:

This outbreak involved 119 cases of C. auris candidemia with an overall mortality rate of approximately 54% and clonal spread from a likely index patient to multiple wards. All isolates were resistant to fluconazole, and the study reported the first echinocandin-resistant C. auris isolates in Türkiye. The authors concluded that C. auris represents an increasing public health threat requiring strengthened infection prevention, surveillance, and attention from healthcare professionals and researchers.