Preventing and treating Trichophyton indotineae
Prevention
Specific recommendations to prevent T. indotineae infection do not exist, but physicians can educate patients about strategies for preventing dermatophyte infections in general.
Health care professionals should use Standard Precautions when caring for patients with possible tinea.
Empiric treatment
Because confirmatory testing may take weeks, it is reasonable to empirically start treatment for T. indotineae based on patient epidemiologic and clinical features while awaiting confirmatory testing. Potassium hydroxide (KOH) preparation of skin scrapings should be performed in clinic, whenever possible, to confirm fungal infections.1
Treatment duration
Treatment may be anticipated to last 6–8 weeks and is given until complete clinical clearance from all infected sites and, ideally, a negative KOH preparation of skin scrapings.1 Longer durations of therapy have been reported (up to 20 weeks) in order to achieve cure.2 Relapses even with long durations of therapy have been reported.
Antifungal selection1
Itraconazole
While there are no current international standardized treatment guidelines, first-line treatment dose is generally considered to be 100 mg/d or 200 mg/d.3
Itraconazole has numerous drug-drug interactions due to CYP enzyme inhibition. Physicians can work with pharmacists to check for drug-drug interactions before prescribing or dispensing itraconazole.
Itraconazole has various formulations and different recommendations for administration. Patients taking itraconazole capsules should take this medication with food and an acidic beverage (e.g., orange juice, cola) to increase absorption. Patients taking itraconazole suspension should take this medication on an empty stomach.
Itraconazole has a black box warning for cardiac toxicity. There may be a greater risk of cardiac toxicity with higher doses of itraconazole.
Any signs of liver disease, including jaundice, pruritus, an unexplained increase in liver function tests, and nausea or vomiting, could indicate hepatotoxicity.4
Transient as well as permanent hearing loss has been reported in patients receiving treatment with itraconazole.5
Terbinafine
Given at higher than usual dose (250 mg twice daily) has been successfully used to treat T. indotineae in some patients, though close monitoring is recommended as this dose has not consistently shown efficacy. Clinicians may consider closer liver enzyme monitoring, though no established parameters for laboratory monitoring at higher terbinafine doses exist.
Griseofulvin and fluconazole
These are not considered first line. This is because studies from India have shown low efficacy and high minimum inhibitory concentrations for these drugs against T. indotineae. However, these medications have been used successfully in select cases and may be considered on a case-by-case basis (for example, if patients fail to improve on terbinafine, yet itraconazole is contraindicated).
Voriconazole
This drug that is normally used for invasive fungal infections, has been used in cases of itraconazole resistance, which is currently considered rare.6,7 Voriconazole has numerous drug-drug interactions due to CYP enzyme inhibition and side effects. Voriconazole is very photosensitizing and has been associated with accelerated photo-carcinogenesis. Use of this medication should generally occur under the guidance of an infectious diseases specialist and only after confirming the patient has either failed an appropriate course of itraconazole or cannot tolerate itraconazole and has failed other antifungals.
Combination oral therapy
Combining different oral antifungals is generally not recommended.
Combination oral/topical therapy
More data are needed to establish the role of combination topical and oral antifungal medications. Dermatologists may consider such combination therapy. It is unknown whether topical antifungals may limit spread of dermatophyte spores.
Itch
Patients with T. indotineae often report extreme pruritus. In addition to antifungal treatments, clinicians should ensure that patients are not using topical corticosteroid treatments. Instead, physicians can consider recommending or prescribing antihistamines for itch.
It is important to note that post-tinea xerosis, itch, and dermatographism are reported. Pruritus may also suggest active and ongoing dermatophytosis. Clinical evaluation is important; KOH preparation of skin scrapings can help confirm mycologic resolution.1
Patient counseling
Physicians can counsel patients on several points:1
The need for prolonged therapy.
The importance of adherence to the medication and follow-up.
The need to avoid sharing personal items and clothing.
Clothing, towels, bedding, and similar shared items should be laundered on high heat.8
The possibility of relapse or recurrence.
Potential side effects from antifungals.
Dermatophyte spores can be killed with common disinfectants like diluted chlorine bleach (1/4 cup per gallon water), benzalkonium chloride, or strong detergents.
If pets are present in the home and also develop skin lesions, the pet should be evaluated by a veterinarian.
Some U.S. physicians have reported challenges with getting itraconazole approved by insurance companies. Cost Plus pharmacy* is one option for obtaining affordable antifungals for people with insurance; it also offers affordable antifungals without insurance.
Antifungal susceptibility testing (AFST) and minimum inhibitory concentration (MIC) data
The goal of AFST is to produce MIC values to guide therapy, inform epidemiological studies, and track antifungal drug resistance9-11.
Definitions
Term | Definition11-13 |
---|---|
Minimal inhibitory concentration (MIC) |
|
Breakpoint |
|
Epidemiologic (ecologic) cutoff value (EVC or ECOFF) |
|
No established breakpoints exist for antifungals in dermatophytosis
This means you cannot look at a laboratory derived MIC value to determine whether a dermatophyte will be resistant to that antifungal.
Currently, ECOFFs are not established for T. indotineae.
Predicting T. indotineae responsiveness
A large body of data, largely from isolates collected from patients in India, demonstrates that a terbinafine MIC cutoff of 0.5 ug/mL can predict terbinafine-responsive isolates, and may correlate to specific point mutations in the squalene epoxidase gene.
Mildly elevated terbinafine MIC values may indicate T. indotineae isolates with potential responsiveness to higher than standard doses of terbinafine (see above).
Similar data is more limited for other antifungal medications (see above).
* The Academy is able to share this resource on an informational basis only. This does not represent an endorsement by the Academy. Please compare, evaluate, and consider which resources best meet your needs.
References
Khurana A, Sharath S, Sardana K, Chowdhary A. Clinico-mycological and therapeutic updates on cutaneous dermatophytic infections in the era of Trichophyton indotineae. J Am Acad Dermatol. Apr 3 2024;doi:10.1016/j.jaad.2024.03.024.
Khurana A, Agarwal A, Agrawal D, et al. Effect of Different Itraconazole Dosing Regimens on Cure Rates, Treatment Duration, Safety, and Relapse Rates in Adult Patients With Tinea Corporis/Cruris: A Randomized Clinical Trial. JAMA Dermatol. Sep 14 2022;158(11):1269-78. doi:10.1001/jamadermatol.2022.3745.
Khurana A, Sharath S, Sardana K, Chowdhary A, Panesar S. Therapeutic Updates on the Management of Tinea Corporis or Cruris in the Era of Trichophyton Indotineae: Separating Evidence from Hype-A Narrative Review. Indian J Dermatol. Sep-Oct 2023;68(5):525-540. doi:10.4103/ijd.ijd_832_23.
Lo Re V, 3rd, Carbonari DM, Lewis JD, et al. Oral Azole Antifungal Medications and Risk of Acute Liver Injury, Overall and by Chronic Liver Disease Status. Am J Med. Mar 2016;129(3):283-91 e5. doi:10.1016/j.amjmed.2015.10.029.
Sporanox. Package insert. . Janssen Pharmaceuticals, Inc. . Updated 10/2023. Accessed 6/21/2024, https://www.janssenlabels.com/package-insert/product-monograph/prescribing-information/SPORANOX-Capsules-pi.pdf.
Singh SK, Subba N, Tilak R. Efficacy of Terbinafine and Itraconazole in Different Doses and in Combination in the Treatment of Tinea Infection: A Randomized Controlled Parallel Group Open Labeled Trial with Clinico-Mycological Correlation. Indian J Dermatol. Jul-Aug 2020;65(4):284-289. doi:10.4103/ijd.IJD_548_19.
Singh A, Masih A, Khurana A, et al. High terbinafine resistance in Trichophyton interdigitale isolates in Delhi, India harbouring mutations in the squalene epoxidase gene. Mycoses. Jul 2018;61(7):477-484. doi:10.1111/myc.12772.
Akhoundi M, Nasrallah J, Marteau A, Chebbah D, Izri A, Brun S. Effect of Household Laundering, Heat Drying, and Freezing on the Survival of Dermatophyte Conidia. J Fungi (Basel). May 23 2022;8(5)doi:10.3390/jof8050546.
Berkow EL, Lockhart SR, Ostrosky-Zeichner L. Antifungal Susceptibility Testing: Current Approaches. Clin Microbiol Rev. Jun 17 2020;33(3)doi:10.1128/CMR.00069-19.
Wiederhold NP. Antifungal Susceptibility Testing: A Primer for Clinicians. Open Forum Infect Dis. Nov 2021;8(11):ofab444. doi:10.1093/ofid/ofab444.
Lockhart SR, Ghannoum MA, Alexander BD. Establishment and Use of Epidemiological Cutoff Values for Molds and Yeasts by Use of the Clinical and Laboratory Standards Institute M57 Standard. J Clin Microbiol. May 2017;55(5):1262-1268. doi:10.1128/JCM.02416-16.
Shaw D, Singh S, Dogra S, et al. MIC and Upper Limit of Wild-Type Distribution for 13 Antifungal Agents against a Trichophyton mentagrophytes-Trichophyton interdigitale Complex of Indian Origin. Antimicrob Agents Chemother. Mar 24 2020;64(4)doi:10.1128/AAC.01964-19.
Bouchara J-P, Nenoff P, Gupta AK, Chaturvedi V. Dermatophytes and dermatophytoses. Springer; 2021.
Additional resources
Access Academy guidance on recognizing signs of infection by T. indotineae.
See Academy guidance on T. mentagrophytes type VII and other emerging dermatophytes.
See Academy information on T. rubrum resistant to terbinafine.
Report suspected cases of antifungal-resistant dermatophytosis, mpox, and COVID-19.