Widespread tinea corporis and tinea cruris resistant to multiple antifungals in India in recent years has been attributed to a hypervirulent, terbinafine-resistant strain. Which organism and mechanism is responsible?

• A Trichophyton violaceum — azole efflux pumps
• B Trichophyton indotineae — squalene epoxidase point mutation (SQLE gene) ✓
• C Trichophyton rubrum — lanosterol demethylase mutation
• D Microsporum canis — biofilm formation

Explanation

The epidemic of recalcitrant tinea in India is caused by Trichophyton indotineae (formerly misidentified as T. mentagrophytes ITS type VIII). It carries mutations in the squalene epoxidase (SQLE) gene that render it resistant to terbinafine. The SQLE mutation F397L is the most common. Treatment requires azoles (itraconazole 200mg/day for 4–8 weeks) or voriconazole for refractory cases; combination regimens are often needed. This is a major recent development in Indian dermatology.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.