Clinical characteristics, healthcare-associated exposures, and antifungal susceptibility patterns of Candida auris colonization and invasive infections: a retrospective observational study at a single center in Turkey

BACKGROUND: Candida auris (Candidozyma auris) differs from other yeast species by its ability to persist for prolonged periods on environmental surfaces and human skin. This feature facilitates person-to-person transmission and contributes to healthcare-associated infections and outbreaks. In this study, both invasive C. auris infections and colonization were evaluated together. We aimed to compare clinical characteristics and healthcare-associated exposures between invasive and colonized cases and to assess antifungal susceptibility patterns in invasive infections. METHODS: A total of 79 patients with C. auris isolation between December 2022 and April 2025 were retrospectively analyzed. Species identification was confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Patients with C. auris isolated from invasive specimens, such as blood or tissue, were classified as having invasive infection, whereas those with isolation from non-invasive specimens such as axilla/groin swabs, nasal swabs, urine, catheters, and sputum, without concurrent invasive positivity, were classified as colonized. Patients with both screening and invasive positivity were included in the invasive infection group for comparative analyses. Antifungal susceptibility to amphotericin B, fluconazole, micafungin, and anidulafungin was determined on invasive isolates using the Sensititre YeastOne colorimetric microdilution method. Interpretation of results was based on the tentative breakpoints defined by the United States Centers for Disease Control and Prevention and the epidemiological cutoff values established by the European Committee on Antimicrobial Susceptibility Testing. Demographic characteristics, clinical variables, and healthcare-associated exposures were compared between the invasive infection and colonization groups. RESULTS: A total of 91 C. auris isolates from 79 patients were evaluated. Invasive infection was detected in 41 patients (52%) and colonization in 38 patients (48%). Most cases were observed in intensive care and palliative care units. Among screening sites, axilla/groin swabs showed the highest positivity rate. Central venous catheter use, intubation, surgical history, and decubitus ulcer were numerically more frequent among invasive cases; however, none of these differences reached statistical significance. Echinocandin resistance developed in two patients during follow-up. The median age was significantly higher in the invasive group than in the colonized group (74 vs. 64.5 years; p = 0.002). CONCLUSION: Accurate identification of C. auris and continuous antifungal susceptibility surveillance are essential for infection control. Older age was the only variable significantly associated with invasive infection, while other clinical and healthcare-associated exposures were common in both groups but did not differ significantly. All isolates were resistant to fluconazole, and echinocandin resistance emerged in two isolates. Amphotericin B susceptibility findings should be interpreted cautiously, as the use of Sensititre YeastOne without confirmatory reference testing may have overestimated resistance. Larger multicenter studies are needed to better define factors independently associated with invasive infection.