What’s the latest on treating cutaneous dermatophyte infections in the era of Trichophyton indotineae?
Clinical Applications
By Sylvia Hsu, MD, FAAD, March 1, 2025
In this month’s Clinical Applications column, DermWorld Editorial Advisory Workgroup member Sylvia Hsu, MD, FAAD, talks to Ananta Khurana, MD, Kabir Sardana, MD, and Anuradha Chowdhary, MD, about their JAAD paper, ‘Clinico-mycological and therapeutic updates on cutaneous dermatophyte infections in the era of Trichophyton indotineae.’
DermWorld: Could you please explain the relationship between Trichophyton mentagrophytes and Trichophyton indotineae?
DermWorld: What is your first-line antifungal medication for Trichophyton indotineae?
DermWorld: What dose would you start with and for how long would you use this drug before giving up and switching to another antifungal?
Dr. Khurana: I start itraconazole at a dose of 100 mg once daily (conventional pellet-based formulation). If a super bioavailable formulation is used, the dose is 50 mg/65 mg once daily. As it is amply evident that T. indotineae infections take a long time to clear, treatment must be prolonged. Roughly, 6-7 weeks are required for most cases. With itraconazole, patients should achieve around 50% clearance by around three weeks of treatment (although a complete cure would, of course, take much longer) and hence a decision as to the expected outcome with treatment can be made at that point. Although true failures to itraconazole are rare in actual clinical settings (and most studies reporting low cure rates with the drug are limited by a short treatment duration), if faced with a scenario of minimal response in 3-4 weeks, a hike in dose can be considered.
DermWorld: I recently treated a man from India for tinea faciei. I gave him terbinafine 250 mg po daily for one month without improvement. Fungal culture revealed Trichophyton mentagrophytes. I then switched him to itraconazole 200 mg po daily with food for one month. He failed that too. What do you recommend?
Dr. Khurana: One cause of failure to itraconazole in your patient could be the short duration of treatment. We conducted an RCT to compare different doses and found that mean durations of treatment required to achieve cure with 100 mg, 200 mg, and 400 mg of itraconazole are 7.7 weeks, 7.2 weeks, and 5.2 weeks respectively (doi: 10.1001/jamadermatol.2022.3745). Further, owing to high rate of minimum inhibitory concentrations to terbinafine in T. indotineae isolates, it is preferable to use a higher dose of 250 mg twice daily right away (doi: 10.1128/AAC.01038-18).
DermWorld: What is your second-line antifungal medication for Trichophyton indotineae?
Dr. Khurana: Terbinafine is my second-line antifungal for T. indotineae infections, although as I mentioned before, I do use terbinafine as a first-line agent also in many patients. Some examples of such scenarios include patients on drugs with significant pharmacokinetic interactions with itraconazole, intolerance to itraconazole (especially GI discomfort), those who have taken multiple courses of itraconazole before for recurrently relapsing infection, and when quality of itraconazole formulation cannot be ensured.
DermWorld: What dose would you use and for how long?
Dr. Khurana: I start terbinafine directly in a dose of 250 mg twice daily and give it until the patient achieves complete clearance of all lesions. This can take anywhere between 4-8 weeks.
DermWorld: Do you recommend combination treatment with two or more concomitant systemic antifungal medications?
Combination of anti-fungal drugs is not based on the mode of action, but on synergy studies, which can further be tested in clinical trials. An in vitro synergy study on trichophyton isolates with SQLE mutations found that itraconazole synergised with terbinafine, ciclopirox olamine, and luliconazole (doi: 10.1128/AAC.00321-21). Thus, if the clinician desires a combination, these are reasonable (systemic with topical) combinations.
DermWorld: What antifungal medications would you NOT recommend in the treatment of Trichophyton indotineae and why?
Dr. Sardana: Certain drugs like oral fluconazole and griseofulvin are largely ineffective. Also, the use of voriconazole and posaconazole goes against the tenets of antifungal stewardship. In fact, cure rates reported with voriconazole in recent publications are largely similar to those with itraconazole. Some papers published comparing it with itraconazole have not prescribed itraconazole for adequate durations, leading to a false impression of inferiority of itraconazole. Of the topical drugs, amorolfine and clotrimazole are not as effective as other drugs.
Ananta Khurana, MD, is professor in the dermatology, venereology, and leprosy department at Dr. Ram Manohar Lohia Hospital and Atal Bihari Vajpayee Institute of Medical Sciences in New Delhi, India.
Kabir Sardana, MD, is director, professor, and head of the dermatology, venereology, and leprosy department at Dr. Ram Manohar Lohia Hospital and Atal Bihari Vajpayee Institute of Medical Sciences in New Delhi, India.
Anuradha Chowdhary, MD, is professor in the Medical Mycology Unit in the Department of Microbiology at the National Reference Laboratory for Antimicrobial Resistance in Fungal Pathogens at the Vallabhbhai Patel Chest Institute at the University of Delhi in New Delhi, India.
The authors do not have any relevant financial and/or commercial conflicts of interest.
Disclaimer: The views and opinions expressed in this article do not necessarily reflect those of DermWorld.
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