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Emerging antifungal resistance in Trichophyton mentagrophytes: insights from susceptibility profiling and genetic mutation analysis

Summary

This study examined how common skin fungal infections caused by Trichophyton species are becoming resistant to standard antifungal treatments. Researchers tested 131 fungal isolates from China and analyzed their resistance genes to understand why some strains no longer respond to terbinafine and other antifungal drugs. They found that certain genetic mutations, particularly in the SQLE gene, make these fungi resistant to treatment and that different species have different resistance patterns. These findings help doctors better choose treatments and guide the development of new antifungal medications.

Background

Trichophyton species are the leading cause of dermatophytosis globally and are increasingly resistant to antifungal treatments. Established resistance criteria for terbinafine and azoles are absent, and research on resistance mechanisms in Trichophyton is limited. This study addresses the need for comprehensive analysis of antifungal susceptibility and drug resistance mechanisms.

Objective

To analyze antifungal susceptibility and drug resistance gene diversity across T. mentagrophytes, T. interdigitale, and T. indotineae isolates collected in China between 1999 and 2024. The study aimed to identify resistance-associated mutations and establish wild-type upper limit values for antifungal drugs.

Results

T. indotineae showed significantly higher terbinafine resistance with 89.1% of strains containing SQLE substitutions, predominantly Phe397Leu. T. mentagrophytes presented higher terbinafine MICs than T. interdigitale but similar azole susceptibility. CYP51A alterations were associated with itraconazole sensitivity, with specific amino acid changes linked to drug resistance profiles.

Conclusion

The study identified significant genetic diversity in SQLE and CYP51A/B genes correlating with antifungal susceptibility. These findings highlight growing prevalence of antibiotic resistance among Trichophyton species and identify potential target genes for new therapies, emphasizing the need for ongoing monitoring and novel therapeutic development.
  • Published in:Emerging Microbes & Infections,
  • Study Type:Laboratory Research Study,
  • Source: PMID: 39749731, DOI: 10.1080/22221751.2025.2450026
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