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Infection caused by a cryptic fungal species, Blastomyces gilchristii, in a tiger

Summary

A tiger in Tennessee became ill with a serious fungal infection caused by a lesser-known fungus called Blastomyces gilchristii. While blastomycosis is typically caused by a different fungus species, this case represents the first detection of this particular cryptic fungal species in the southeastern United States. Scientists used advanced genetic sequencing to identify the fungus when standard laboratory methods failed. This discovery suggests that this dangerous fungus is spreading to areas where it was not previously thought to exist.

Background

Blastomycosis is typically caused by Blastomyces dermatitidis, but recent advances in sequencing have identified other Blastomyces species. B. gilchristii is a cryptic fungal species previously identified mainly in northern USA and Canada. This report describes the first case of B. gilchristii infection in a tiger in the southeastern USA.

Objective

To describe and characterize an infection caused by the cryptic fungal species Blastomyces gilchristii in an adult female tiger with acute neurological signs. To identify the causative agent through whole-genome sequencing when conventional diagnostic methods were inconclusive.

Results

Fungal isolate showed atypical characteristics with tan, glabrous colonies with prickly centers and lollipop-like conidia. Whole-genome sequencing identified the organism as B. gilchristii with 98% of reads mapping unambiguously to the B. gilchristii reference genome. Antifungal MICs showed susceptibility to itraconazole, posaconazole, and voriconazole.

Conclusion

This is the first documented case of B. gilchristii infection in a tiger and in the southeastern USA, suggesting the geographic range of this cryptic pathogen is wider than previously believed. Whole-genome sequencing is essential for identifying cryptic fungal pathogens and understanding epidemiological patterns. Continued surveillance and identification of these cryptic species is important for understanding disease prevalence and treatment options.
  • Published in:Access Microbiology,
  • Study Type:Case Report,
  • Source: PMID: 40843027, DOI: 10.1099/acmi.0.001011.v3
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