Abstract
ABSTRACT
Trichophyton mentagrophytes
genotype VII (
Tm
VII) is an emerging dermatophyte, primarily associated with sexual transmission, that causes persistent, painful, and inflammatory skin lesions.
Tm
VII is part of the
T. interdigitale/T. mentagrophytes
species complex, which comprises 28 genotypes. To facilitate rapid and specific identification of
Tm
VII
,
a real-time PCR (rt-PCR) assay was developed targeting three unique single-nucleotide polymorphisms in the internal transcribed spacer 1 (ITS1) region. Assay specificity was enhanced by introducing a mismatch at the 3′ ends of both primers. Using genomic DNA (gDNA) from cultured
Tm
VII isolates, the assay demonstrated high sensitivity, detecting as little as 0.0002 ng gDNA per rt-PCR. The assay was highly specific, with no cross-reactivity observed against other fungal pathogens when a cycle threshold cutoff of 37 was used. Among the 497 mold isolates tested, 47 were confirmed as
Tm
VII by rt-PCR, fully concordant with results from the standard ITS-PCR/Sanger sequencing method. The rt-PCR assay demonstrated high sensitivity, specificity, reproducibility, and speed, with a turnaround time of 1 day after DNA extraction compared with 2 to 7 days for Sanger sequencing. Future studies planned with primary skin samples in collaboration with healthcare providers are expected to further enhance the diagnostic utility of the
Tm
VII rt-PCR assay currently developed.
IMPORTANCE
We developed a TaqMan probe-based real-time PCR (rt-PCR) assay to accurately identify the emerging and rapidly spreading
Trichophyton mentagrophytes
genotype VII (
Tm
VII) isolate. Timely identification and appropriate treatment of
Tm
VII infections are essential to limit their spread and improve patient outcomes. Planned studies using primary skin samples, in collaboration with healthcare providers, are expected to further enhance the diagnostic utility of the
Tm
VII rt-PCR assay.