Clinical and Molecular Epidemiological Characteristics of 26 Bloodstream Infection Cases Caused by Candida tropicalis.

Purpose: This study aims to investigate the clinical and molecular epidemiological characteristics of bloodstream infections caused by Candida tropicalis.

Methods: This retrospective study analyzed the clinical data of patients diagnosed with C. tropicalis bloodstream infections from January 2020 to December 2022. Antifungal susceptibility testing was performed. Multilocus sequence typing (MLST) was used to analyze strain homology, and mutation analysis of the ERG11 (azole resistance-associated) and FKS1 (echinocandin resistance-associated) genes was conducted.

Results: Among the 26 cases of C. tropicalis bloodstream infections, hematologic malignancies were the most common underlying condition, with an overall mortality rate of 38.5%. Resistance rates to voriconazole and fluconazole were 30.8%, while the isolates exhibited high susceptibility to echinocandin drugs and amphotericin B. All fluconazole-resistant strains contained mutations in the ERG11 gene, with Y132F and S154F being the most frequent mutation sites. The mortality rate in fluconazole-resistant patients (37.5%) was similar to that of susceptible or dose-dependently susceptible patients (38.8%). A total of 20 distinct sequence types (DSTs) were identified among the 26 strains, all of which were previously known, indicating significant genetic diversity. The most abundant type was DST376.

Conclusion: Hematologic malignancies are the most common underlying disease of C. tropicalis bloodstream infections. The isolated strains demonstrate significant genetic diversity and a high level resistance to fluconazole.