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

Summary

Researchers developed a genetic fingerprinting tool called microsatellite typing to track and identify outbreaks of a dangerous fungus called Trichosporon asahii in hospitals. This fungus causes life-threatening infections, especially in sick patients with weakened immune systems, and is resistant to many antifungal medications. By analyzing samples from hospitals across South America, scientists discovered multiple instances where the same strain of this fungus infected patients in different hospitals over many years. This new testing method is much cheaper and faster than other genetic tests, making it practical for hospitals worldwide to monitor and control infections caused by this emerging pathogen.

Background

Trichosporon asahii is an emerging yeast-like fungal pathogen causing life-threatening nosocomial infections, particularly in immunocompromised patients. The pathogen exhibits intrinsic resistance to echinocandins and shows rising prevalence globally. Current epidemiologic typing tools are lacking for investigating clonal spread of T. asahii in clinical settings.

Objective

To develop a microsatellite typing tool for investigating the genetic relatedness and transmission dynamics of T. asahii isolates. The study aimed to identify nosocomial transmission events and assess the discriminatory power of this typing method compared to existing genotyping approaches.

Results

The microsatellite panel identified 71 genotypes with a Simpson index of diversity of 0.9793, showing superior discriminatory power compared to IGS1 sequencing which identified only 5 genotypes. Multiple nosocomial transmission clusters were identified in Brazilian hospitals, including one spanning 13 years. The panel successfully differentiated isolates by origin, anatomic sites, and isolation year.

Conclusion

The developed microsatellite typing panel offers high reproducibility and specificity as an effective epidemiologic tool for tracking T. asahii outbreaks. This method provides a cost-effective, accessible alternative to whole-genome sequencing for resource-limited settings and can complement IGS1-based genotyping for surveillance of this emerging fungal pathogen.
  • Published in:Emerging Infectious Diseases,
  • Study Type:Molecular Epidemiology Study,
  • Source: 10.3201/eid3109.241929, PMID: 40867019
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