Trichophyton indotineae causes refractory and inflammatory dermatophytosis and is increasing in prevalence1
Dermatophytic fungi, including the commonly isolated Trichophyton spp., cause superficial hair, nail, and skin infections with subsequent hair and nail loss, rash, and pruritis. Trichophyton indotineae (formerly named Trichophyton mentagrophytes type VIII) is a newly described hypervirulent species that causes extensive, severe pruritic infections, often associated with extreme physical discomfort (Figure 1).2
Figure 1:
Tinea corporis infection caused by Trichophyton indotineae.
Image courtesy of Lakeridge Health Infectious Diseases Clinic
Tinea corporis and cruris are typically treated with topical azoles or terbinafine, to which T. indotineae is often resistant2,3
Oral fluconazole or terbinafine are also commonly ineffective.3 Resistant dermatophytes, including T. indotineae infections, have been successfully treated with oral itraconazole, although longer courses or higher doses may be needed than for nonresistant dermatophytes.3,4
Infection by T. indotineae should be suspected in patients with travel history to South Asia or treatment-resistant tinea
An ongoing epidemic of recalcitrant T. indotineae dermatophytosis in India is spreading globally; travel-associated cases have been identified in Canada.2,5 However, not all patients have a history of travel, and documented transmission within North America has also been described.1
Trichophyton indotineae spreads directly through contact with affected humans or indirectly via contaminated items (e.g., towels, linens)3,5
Assessment of travel and exposure history, including sexual exposure, may help facilitate early diagnosis.5
Clinicians should send skin scrapings (and hair or nail samples, if indicated) for fungal culture5
Molecular methods are required for definitive, species-level identification; samples may need to be sent to a specialized reference laboratory.1 Suspicion for T. indotineae should be indicated on requisitions to ensure laboratories are alerted and Trichophyton spp. are identified to the species level. Antifungal susceptibility testing is not routinely performed on filamentous fungi; consultation with a microbiologist may be necessary.
Footnotes
Competing interests: Julianne Kus is chair of the mycology scientific committee with the Institute for Quality Management in Healthcare. None declared.
This article has been peer reviewed.
References
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