Research Progress on Trichophyton indotineae Infection：An Updated Review

Trichophyton indotineae is a recently identified dermatophyte species that has emerged as a causative agent of chronic, treatment-refractory dermatophytosis, predominantly manifesting as tinea cruris or generalised tinea corporis. As of 2025, infections have been reported in more than 40 countries worldwide. Morphologically indistinguishable from the T. mentagrophytes complex, T. indotineae requires identification through mass spectrometry or molecular sequencing. Its genomic structure and virulence profile are highly similar to those of the T. mentagrophytes complex, with limited single nucleotide polymorphism diversity among global isolates. A hallmark of T. indotineae is its frequent resistance to terbinafine, primarily mediated by amino acid substitutions—Phe397Leu, Leu393Phe, or Leu393Ser—in the squalene epoxidase enzyme. Multidrug resistance, including reduced susceptibility to fluconazole, itraconazole, posaconazole, and griseofulvin, has also been observed, particularly among Chinese isolates. Although the mechanisms underlying azole resistance are not fully elucidated, increased copy number of the CYP51B gene has been implicated. Oral itraconazole, administered at high doses or over extended courses, currently represents a preferred therapeutic option. The global spread and antifungal resistance profile of T. indotineae present a growing threat to public health, underscoring the urgent need for enhanced surveillance, resistance monitoring, and effective clinical management strategies.