<i>Trichophyton indotineae</i> – Facts and controversies – A review

Trichophyton indotineae is a new species of fungus named in 2020, which is the same as Trichophyton mentagrophytes internal transcribed spacer region (ITS) genotype 8. It was identified by sequencing the ITS region of ribosomal DNA. It is a clinically significant clonal offshoot of the different ITS types of T. mentagrophytes . This species is the main etiological agent for recalcitrant dermatophytosis in India and neighboring countries like Bangladesh, and is being reported in Europe and the UAE. The name is controversial as it imparts stigma. It is considered that the zoophilic mentagrophytes species underwent anthropization under favorable circumstances, like widespread topical steroid abuse, and it rose to an epidemic level in India. It is resistant to terbinafine and commonly used antifungals such as fluconazole and griseofulvin. It spreads easily from person to person and also causes extensive lesions with involvement of the genitals. Morphologically, this species is similar to T. mentagrophytes and Trichophyton interdigitale , and species identification is possible by DNA sequencing after polymerase chain reaction amplification of the ITS region and comparing it with sequences in the gene bank, which differ only at 2 and 3 nucleotide positions from the ITS sequences of T. mentagrophytes and T. interdigitale , respectively. Itraconazole is still an effective drug against this organism and but even with that, a longer duration of treatment is needed for a cure. Some isolates are sensitive to terbinafine at higher doses. This emerging pathogen is a warning to us to follow strict antifungal and antibiotic stewardship and to implement strict regulations to prevent the availability of over-the-counter medications.