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Emergence of resistant dermatophytosis caused by Trichophyton indotineae: First case series in Thailand

Summary

Doctors in Thailand have identified a new drug-resistant fungal infection caused by Trichophyton indotineae, a fungus that doesn’t respond to common antifungal medication terbinafine. Five patients were diagnosed with this resistant skin infection that caused rashes on various body parts and failed to improve with standard treatments. The research shows that a simple urease test can help doctors quickly identify this resistant fungus, and a different drug called itraconazole appears to work better for treatment. This is the first time this resistant fungus has been confirmed in Thailand, suggesting it is spreading globally.

Background

Trichophyton indotineae is a terbinafine-resistant dermatophyte first reported in India in 2018 and subsequently identified in Japan and several other countries. This fungus has spread globally across Asia, USA, Latin America, and Europe, but had not been previously reported in Thailand. The emergence of this resistant species represents a significant clinical challenge in dermatological treatment.

Objective

To identify and characterize Trichophyton indotineae infections in Thai patients through screening of culture-positive specimens with Trichophyton mentagrophytes complex morphology. The study aimed to confirm cases through molecular analysis and assess the prevalence of antimicrobial resistance genes in these isolates.

Results

Five Thai patients were diagnosed with Trichophyton indotineae infection, all with negative urease test results confirmed by ITS sequencing. Two of five isolates (40%) harbored SQLE gene mutations at position Phe397Leu (1191C>A and 1189T>C). Two isolates showed high MIC values >1 mg/L for terbinafine, confirming drug resistance. Most patients responded well to itraconazole treatment.

Conclusion

This is the first confirmed case series of Trichophyton indotineae in Thailand, indicating the spread of terbinafine-resistant dermatophytosis to the country. The urease test was effective as a simple screening tool, and itraconazole emerged as the preferred treatment option. Larger studies are needed to determine the true prevalence and establish optimal diagnostic and therapeutic protocols.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Series,
  • Source: PMID: 40547227
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