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Volume 32, Number 9—September 2026
Research
Dual PCR–Sanger Sequencing Assay for Simultaneous sqle-Based Identification and Resistance Detection in Trichophyton Species
, Karin M. Jørgensen, Karen Marie Thyssen Astvad, and Maiken Cavling Arendrup
Table 2
Species identification and sqle alterations detected by direct PCR and sequencing of a partial 388-bp sqle gene fragment from clinical specimens positive for Trichophyton spp. in study of dual PCR–Sanger sequencing assay for simultaneous sqle-based identification and resistance detection in Trichophyton species*
| Initial ITS-based identification | Specimen types | No. clinical samples | Final species identification (sqle sequencing) |
SQLE variant(s) |
|---|---|---|---|---|
| T. rubrum |
Nail, skin scraping |
24 |
T. rubrum complex† |
Wild-type, n = 19 |
| L393, n = 1 |
||||
| F397L, n = 2 |
||||
| F415S, n = 1 |
||||
| L427M, n = 1 |
||||
| T. mentagrophytes complex‡ |
Nail, skin scraping |
28 |
T. interdigitale (n = 16) |
Wild-type, n = 16 |
| T. indotineae (n = 11) |
Wild-type, n = 1 |
|||
| T. mentagrophytes (n = 1) |
Q408L, n = 4 |
|||
| F397L, n = 3 |
||||
| A448T, n = 2 |
||||
| F397L/A448T, n = 1 |
||||
| Wild-type, n = 1 |
||||
| T. tonsurans/T. equinum |
Hair, skin scraping |
4 |
T. tonsurans |
Wild-type, n = 4 |
| T. violaceum |
Hair, scalp |
2 |
T. rubrum complex† |
Wild-type, n = 2 |
| Trichophyton spp.‡ |
Scalp |
4 |
T. rubrum complex† |
Wild-type, n = 4 |
| T. benhamiae complex | Hair, skin scraping | 4 | T. benhamiae sensu stricto clade | Wild-type, n = 4 |
*Initial species identification was based on ITS analysis, with final identification resolved by sqle sequencing. Detected sqle variants include both wild-type and amino acid substitutions within the terbinafine resistance hotspot region. ITS, internal transcribed spacer; SQLEe, squalene epoxidase. †Indicates assignment to species complexes where species-level resolution was not achieved. ‡Further identification not possible.