Two different types of tandem sequences mediate the overexpression of TinCYP51B in azole-resistant Trichophyton indotineae

is an emerging dermatophyte that causes severe tinea corporis and tinea cruris. Numerous cases of terbinafine- and azole-recalcitrant -related dermatophytosis have been observed in India over the past decade, and cases are now being recorded worldwide. Whole genome sequencing of three azole-resistant strains revealed a variable number of repeats of a 2,404 base pair (bp) sequence encoding in tandem specifically at the locus position. However, many other resistant strains (itraconazole MIC ≥0.25 µg/mL; voriconazole MIC ≥0.25 µg/mL) did not contain such duplications. Whole-genome sequencing of three of these strains revealed a variable number of 7,374 bp tandem repeat blocks harboring . Consequently, two types of azole-resistant strains were found to host in tandem sequences (type I with 2,404 bp blocks and type II with 7,374 bp blocks). Using the CRISPR/Cas9 genome-editing tool, the copy number of within the genome of types I and II strains was brought back to a single copy. The azole susceptibility of these modified strains was similar to that of strains without duplication, showing that azole resistance in strains is mediated by one of two types of amplification. Type II strains were prevalent among 32 resistant strains analyzed using a rapid and reliable PCR test.