Detection of Multiple Nosocomial Trichosporon asahii Transmission Events via Microsatellite Typing Assay, South America

The fungus Trichosporon asahii has emerged as a cause of nosocomial infections, particularly in immunocompromised patients. Given its rising prevalence, information on its genetic diversity and transmission dynamics is urgently needed. We developed a microsatellite typing tool to investigate the genetic relatedness of T. asahii isolates. We selected 6 microsatellite markers from nanopore long-read sequencing of the T. asahii type-strain CBS 2479. We applied those markers to 111 clinical and environmental isolates; microsatellite typing showed high variability among isolates (11-37 alleles per marker) and identified 71 genotypes with strong discriminatory power (Simpson index of 0.9793). We applied the microsatellite typing method to T. asahii isolates from South America and identified multiple nosocomial transmission events from hospitals in Brazil, including clusters spanning more than a decade. The panel we developed offers high reproducibility and specificity, making it an effective tool for tracking outbreaks and determining the public health effects of T. asahii infections.