Distribution and Antifungal Susceptibility of<i> Candida</i><i> auris</i> Isolates from Clinical Samples in a Tertiary Care Hospital: A Four-Year Retrospective Study

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EVREN K., Oncel B., Komec S.

FLORA INFEKSIYON HASTALIKLARI VE KLINIK MIKROBIYOLOJI DERGISI, cilt.30, sa.4, ss.440-446, 2025 (ESCI, TRDizin)

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Introduction: Candida auris is a significant pathogen that needs to be considered, particularly in intensive care units, due to its ability to survive for extended periods on hospital surfaces, resistance to disinfectants, tendency to cause colonization in patients, the challenges in identification, and multidrug antifungal resistance. This study aimed to characterize the antifungal susceptibility profile of clinical C. auris isolates identified in our laboratory as causative agents of infection. Material and Methods: Between January 2021 and November 2024, data from patients with C. auris growth in clinical cultures were retrospectively analyzed. For patients with multiple isolates, only the first isolate was included. Presumptive colonies were identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems (Microflex LT, Bruker Daltonics, Germany, and EXS2600, Zybio Inc., China). Antifungal susceptibility testing was performed using the Sensititre YeastOne system (Trek Diagnostic Systems, United Kingdom) in accordance with the manufacturer's instructions. Minimum inhibitory concentrations (MICs) were determined for amphotericin B, fluconazole, voriconazole, posaconazole, itraconazole, caspofungin, anidulafungin, micafungin, and flucytosine. MIC distributions, MIC50, MIC90, and geometric mean (values were calculated. The susceptibility of isolates was interpreted based on the Centers for Disease Control and Prevention tentative clinical breakpoints. Results: Among the 414 patients with C. auris isolated from at least one clinical specimen, 226 were male and 188 were female. The age range was 0-100 and the median age was 67, interquartile range was 25 (Q1:53, Q3:78). Based on specimen type distribution, C. auris was most frequently isolated from groin/axillary surveillance cultures (n= 159), followed by blood cultures (n= 148), urine samples (n= 68), intravascular catheter tips (n= 21), tracheal aspirates (n= 12), wound samples (n= 5), and one tissue specimen. Antifungal susceptibility testing was performed on 150 isolates, and resistance rates were determined according to CDC tentative breakpoint criteria for fluconazole, amphotericin B, caspofungin, anidulafungin, and micafungin. Resistance rates for fluconazole, amphotericin B, caspofungin, micafungin, and anidulafungin were determined as 94.67%, 71.37%, 26.67%, 0.67% and 0.67%, respectively. One isolate also had resistance to echinocandin, amphotericin B, and fluconazole. Conclusion: The fluconazole resistance rate identified in this study (94.67%) was found to be consistent with the resistance rates reported in the literature. The high resistance rates observed for amphotericin B and caspofungin are thought to be potentially related to the testing method used. Therefore, careful interpretation of these results is essential, and epidemiological surveillance of antifungal resistance rates remains crucial.