Distribution and antifungal susceptibility of clinical Trichosporon spp. isolates: 10 years of single-center experience

Purpose: The genus Trichosporon, which is a yeast-like basidiomycete, is ubiquitous in nature and a part of human microbiota. It’s an oppurtunistic fungal pathogen, which was once rare, but increasing dramatically recently, leading to fatal infections. The aim of this study was to determine the prevalence, and antifungal susceptibility of clinical Trichosporon spp. isolates, and to determine whether there was a change in incidence during the COVID-19 Pandemic. Materials and Methods: This was a retrospective cross-sectional descriptive study, conducted between January 1, 2013 and February 5, 2023. Cultures which Trichosporon spp. isolated (n=125) were screened, and those met the eligibility criteria were included (n=77). Identification, antifungal susceptibility test results, age, gender records were identified from Microbiology Laboratory Information Management System. Results: 97.4% of the isolates were Trichosporon asahii, and 2.6% were Trichosporon mucoides. The most frequent isolation period was the 2016 and 2019 year group (71.4%), not during the COVID-19 Pandemics (19.5%). The most common sample type was urine (58.4%), of whom predominantly (58.4%) hospitalized in the Intensive Care Unit. Amphotericin B MICs were ≤1µg/ml in 68.9% of the isolates. Fluconazole and voriconazole MICs were ≤1µg/ml in 20.0% and 94.8%, respectively. 59.7% of the isolates had a MIC of ≥4µg/ml for flucytosine. Micafungin and caspofungin MICs were ≥4µg/ml in 88.3% and 92.2% of the isolates, respectively. Voriconazole had the strongest in vitro activity, and amphotericin B had lower MICs than expected. The combination therapy of voriconazole and amphotericin B could be a therapeutic option in this setting, as well as monotherapy of voriconazole. Conclusion: Trichosporon spp. isolated in clinical specimens and their antifungal susceptibility depend on the geographic region and the anatomic site. Identifying local data will contribute to both the management of these patients, and surveillance studies.