Retrospective Multicenter Study on Invasive Candidiasis in Türkiye Demonstrates High Genetic Variety of Candida tropicalis.

Candida tropicalis frequently causes invasive infections in immunocompromised hosts. Mortality rates are high compared to other yeasts, while antifungal resistance varies between countries. To date, multicenter studies regarding C. tropicalis infections in Türkiye are limited. The current study therefore characterized C. tropicalis infections in Türkiye. In this retrospective study, 120 invasive C. tropicalis isolates were collected from four hospitals in Türkiye, mostly from blood. In vitro antifungal susceptibility testing (AFST) was performed for eight common antifungals, and short tandem repeat (STR) genotyping was applied to investigate genetic relatedness within the current population and previously genotyped isolates. Patients with invasive C. tropicalis candidiasis were mostly elderly, with a central venous line (CVL) and cancer or diabetes as underlying disease, and an overall mortality rate of 37%. Except for a single isolate from blood being resistant to fluconazole and voriconazole, no resistance to common antifungals was found. Finally, nosocomial transmission within hospitals was limited as nearly all isolates displayed unique genotypes. When compared to 605 previously investigated isolates from 12 diverse countries, only few clusters were present, indicating an overall high genetic diversity for C. tropicalis. While isolates from the current study did not form a single monophyletic branch, there were 27 isolates that formed a distinct pan-susceptible clade together with isolates of other Middle Eastern countries. To conclude, we described a retrospective multicenter study on invasive C. tropicalis infections in Türkiye characterized by a high mortality rate for untreated patients, while isolates showed little antifungal resistance and high genetic diversity.