To establish an efficient, sensitive and accurate method for the detection of dermatophytosis by using the real-time fluorescence technique based on loop-mediated isothermal amplification, so as to realize the rapid laboratory diagnosis of dermatophytosis.

By searching and downloading the rRNA sequences of the strains with high clinical isolation rates of Trichophyton, Microsporum and Epidermophyfon from the NCBI website, DNASTAR Lasergene software was used for analysis and comparison to find the highly conserved target sequences of Trichophyton, which were different from those of other genera. LAMP primers that included a pair of internal primers, external primers and ring primers were designed using Primer Explorer V5. The NBRC6202 genomic DNA of Trichophyton mentagrophytes was extracted as a template for screening primers and a LAMP reaction system was established for the detection of Trichophyton. The sensitivity and stability of this reaction system were tested by using the ATCC28188 genomic DNA of T. rubrum. The specificity of LAMP reaction system was verified by the genomic DNA of other fungi and bacteria other than Trichophyton.

Among the 4 sets of primers screened, primer2 had a good amplification effect and was able to detect T. mentagrophytes within 22 min. Moreover, T. rubrum, T. interdigitale, T. verrucosum, T. schoenleinii and T. violaceum could be specifically detected. The minimum detection limit of LAMP detection system established in this study was 1 pg/μL. The average CT value and CV% were 9.24±0.30, 3.29%, 10.57±0.54, 5.12%, 15.95±0.52, 3.24% at 10 000 pg/μL, 100 pg/μL, and 1 pg/μL, respectively. The peaking time was stable.

The LAMP method of Trichophyton showed superior performance in specificity, sensitivity and stability, which can quickly and accurately detect common strains of Trichophyton, and had a good clinical application prospect.