Clonal Candida auris candidemia outbreak in a tertiary care center with the first echinocandin-resistant isolates...

Candida auris has emerged as a global public health threat because of its antifungal resistance and propensity for nosocomial transmission. This study characterized a C. auris outbreak at a tertiary care center in Türkiye and investigated its transmission dynamics and antifungal resistance.

C. auris candidemia cases identified between April 2023 and September 2025 were included, and clinical data were retrospectively collected. Antifungal susceptibility testing was performed by CLSI broth microdilution against eight antifungal agents. For echinocandin-resistant isolates, hotspot region 1 of FKS1, was sequenced. Short tandem repeat genotyping was used to assess genetic relatedness.

A total of 119 patients developed C. auris bloodstream infection, with an overall 30-day mortality rate of 54%. Cases were identified across 21 wards, most commonly in the internal medicine ICU and the anesthesia and reanimation ICU. All isolates were resistant to fluconazole. Two patients with prior echinocandin exposure were infected with echinocandin-resistant isolates harboring FKS1^S639P. Genotyping assigned all isolates to clade I and identified three closely related genotypes. Epidemiological tracing, integrated with genotyping data indicated that the first identified patient was the single source of the outbreak, which subsequently spread to multiple wards without additional introductions.

C. auris has established a presence in Türkiye, as demonstrated by this first large outbreak of invasive cases at a tertiary care center. Although fluconazole resistance was universal, the detection of echinocandin-resistant isolates underscored the need for strengthened infection prevention measures. Epidemiological and molecular typing data indicated the spread of a single strain across multiple wards.