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The Rise of Antifungal-Resistant Dermatophyte Infections: What Dermatologists Need to Know
Worldwide, it is estimated that up to 1 in 5 individuals will experience a dermatophyte infection (commonly called ringworm or tinea infection) in their lifetime.1 Historically, dermatophyte infections have been considered relatively minor conditions usually treated with short courses of topical antifungals.2 Oral antifungals historically were needed only for patients with nail or hair shaft infections or extensive cutaneous fungal infections, which typically occurred in immunosuppressed patients.2 However, the landscape is changing rapidly due to the global emergence of severe dermatophyte infections that frequently are resistant to first-line antifungal medications.3-5 In this article, we aimed to review the epidemiology of emerging dermatophyte infections and provide dermatologists with information needed for effective diagnosis and management.
Emergence of Trichophyton indotineae
In recent decades, public health officials and dermatologists have noted with concern the spread of the recently emerged dermatophyte species Trichophyton indotineae in South Asia.3,6 This species (previously known as Trichophyton mentagrophytes genotype VIII) usually is transmitted from person to person, either through direct skin-to-skin contact or by fomites.4,6 Potential sexual transmission of T indotineae infections also has been reported,7 and it is possible that animals may serve as reservoirs for this pathogen, although there are no known reports of direct spread from animals to humans.8,9 Major outbreaks of T indotineae are ongoing in South Asia, and cases have been documented in 6 continents.10-12 In the United States, most but not all cases have occurred in immigrants from or recently returned travelers to South Asia.6,13 The emergence and spread of T indotineae is hypothesized to be promoted by the misuse and overuse of topical antifungal products, particularly those containing combinations of potent corticosteroids with other antimicrobial drugs.14,15
Cutaneous manifestations of T indotineae infections tend to cover large body surface areas, recur frequently, and pose substantial treatment challenges.6,13,16 Several clinical presentations have been documented, including erythematous, scaly concentric plaques; papulosquamous lesions; pustular forms; and corticosteroid-modified disease (Figure 1).6,16 Affected patients seldom are immunocompromised and often have a history of multiple failed courses of topical or oral antifungals, including oral terbinafine.13 Many also have been prescribed topical corticosteroids or have used over-the-counter topical corticosteroids, which worsen the rash.17
Direct microscopy with potassium hydroxide could be used to confirm the diagnosis of dermatophyte infection, but it does not distinguish T indotineae from other dermatophyte species.2,6 Importantly, culture-based testing usually will misidentify T indotineae as other Trichophyton species such as the more common T mentagrophytes or Trichophyton interdigitale. Definitive identification of T indotineae requires advanced molecular techniques that are available only at select laboratories.6 Unfortunately, availability of such testing is limited (Table), and results may take several weeks; therefore, it is suggested that dermatologists who suspect T indotineae infections based on the patient’s history and clinical presentation begin antifungal treatment after confirmation of dermatophyte infection but not wait for definitive confirmation of the causative organism.16
Itraconazole is considered the first-line therapy for T indotineae infection, as terbinafine usually is ineffective due to mutations in the squalene epoxidase gene.16 Dermatologists should be aware that itraconazole is available in different formulations that can affect absorption. The oral solution has greater bioavailability and should be taken on an empty stomach, whereas the capsules are required to be taken with food for effective absorption; the capsules also should be taken with an acidic beverage such as orange juice. Dermatologists should carefully assess for drug-drug interactions when prescribing itraconazole, given its extensive interaction profile with numerous other medications. Patients may require treatment with itraconazole (100 mg/d or 200 mg/d) for a minimum of 6 to 8 weeks until complete clearance has been achieved and ideally a negative potassium hydroxide preparation of skin scrapings has been obtained. A longer treatment period (eg, ≥3 months) frequently is needed, and relapses are common.6,16,18 Regular follow-up is needed to monitor for infection clearance and recurrences. It is important to note that cases of itraconazole resistance have been reported, although this currently appears to be uncommon.19,20
Other Emerging Dermatophytes to Watch
Trichophyton rubrum is the most common cause of dermatophyte infections among humans,21 and cases of terbinafine-resistant T rubrum infections have been reported increasingly in the United States and Canada.5,22-24 Onychomycosis caused by terbinafine-resistant T rubrum has been documented, and patients may have infections that do not respond to terbinafine given at the standard dose and duration.22,23 Case reports have indicated successful treatment using itraconazole 200 mg/d and posaconazole 300 mg/d.5,23
Trichophyton mentagrophytes genotype VII (TMVII) is an emerging dermatophyte that recently has been reported as a cause of sexually transmitted dermatophyte infections in Europe and the United States primarily affecting men who have sex with men.25-27 Patients may present with pruritic, annular, scaly patches and plaques involving the trunk, groin, genital region, or face (Figure 2). Although closely related to T indotineae, TMVII differs in that it more often affects the genital region, generally is susceptible to terbinafine, and in the United States and Europe usually is not related to travel or immigration involving South Asia.26 Although TMVII has not been associated with antifungal resistance, awareness among dermatologists is important because patients may experience inflamed, painful, and persistent rashes that can lead to secondary bacterial infection or scarring, and physicians might mistake it for mimics including eczema or psoriasis.25,26
Importance of Judicious Antifungal Use
Optimizing the use of antifungals is critical to improving patient outcomes and preserving available treatment options.28,29 A retrospective analysis of commercial health insurance data estimated that topical antifungal prescriptions were potentially unnecessary for more than half of the more than 560,000 patients who were prescribed these medications in 2023. In this study, it also was observed that only 16% of patients prescribed a topical antifungal had received diagnostic testing, with low rates across specialties.30 This is concerning because even among board-certified dermatologists, incorrect diagnosis of suspected fungal skin infections can occur; in one survey-based study of board-certified dermatologists who were presented with dermatomycosis images, respondents categorized cases with greater than 75% accuracy in only 31% (4/13) of instances.31 Clotrimazole-betamethasone is among the most commonly prescribed topical antifungals in the United States,14,32 and 2 recent retrospective analyses highlighted that the majority of patients prescribed this medication did not receive any fungal diagnostic testing.33,34
Final Thoughts
In an era of emerging antifungal-resistant dermatophyte infections, it is important for dermatologists to educate nondermatologists about the importance of using diagnostic testing for suspected dermatophyte infections.14,28 Dermatologists also can educate nondermatologist colleagues on the importance of avoiding the use of topical combination antifungal/corticosteroid medications and referring for dermatologic evaluation when diagnoses are uncertain.33,34 Strategies for education by dermatologists could include giving workshops, creating educational materials, and fostering open communication about optimal treatment practices and referral parameters for suspected dermatophyte infections.
- Noble SL, Forbes RC, Stamm PL. Diagnosis and management of common tinea infections. Am Fam Physician. 1998;58:163-174, 177-168.
- Ely JW, Rosenfeld S, Seabury Stone M. Diagnosis and management of tinea infections. Am Fam Physician. 2014;90:702-710.
- Uhrlaß S, Verma SB, Gräser Y, et al. Trichophyton indotineae—an emerging pathogen causing recalcitrant dermatophytoses in India and worldwide—a multidimensional perspective. J Fungi (Basel). 2022;8:757. doi:10.3390/jof8070757
- Verma SB, Panda S, Nenoff P, et al. The unprecedented epidemic-like scenario of dermatophytosis in India: I. epidemiology, risk factors and clinical features. Indian J Dermatol Venereol Leprol. 2021;87:154-175.
- Chen E, Ghannoum M, Elewski BE. Treatment]resistant tinea corporis, a potential public health issue. Br J Dermatol. 2021;184:164-165.
- Caplan AS. Notes from the field: first reported US cases of tinea caused by Trichophyton indotineae—New York City, December 2021–March 2023. MMWR Morbidity and Mortality Weekly Report. 2023;72:536-537. doi:10.15585/mmwr.mm7219a4
- Spivack S, Gold JA, Lockhart SR, et al. Potential sexual transmission of antifungal-resistant Trichophyton indotineae. Emerg Infect Dis. 2024;30:807.
- Jabet A, Brun S, Normand AC, et al. Extensive dermatophytosis caused by terbinafine-resistant Trichophyton indotineae, France. Emerg Infect Dis. 2022;28:229-233.
- Thakur S, Spruijtenburg B, Abhishek, et al. Whole genome sequence analysis of terbinafine resistant and susceptible Trichophyton isolates from human and animal origin. Mycopathologia. 2025;190:13.
- Lockhart SR, Chowdhary A, Gold JA. The rapid emergence of antifungal-resistant human-pathogenic fungi. Nat Rev Microbiol. 2023;21:818-832.
- Mosam A, Shuping L, Naicker S, et al. A case of antifungal-resistant ringworm infection in KwaZulu-Natal Province, South Africa, caused by Trichophyton indotineae. Public Health Bulletin South Africa. Accessed April 4, 2025. https://www.phbsa.ac.za/wp-content/uploads/2023/12PHBSA-Ringworm-Article-2023.pdf
- Cañete-Gibas CF, Mele J, Patterson HP, et al. Terbinafine-resistant dermatophytes and the presence of Trichophyton indotineae in North America. J Clin Microbiol. 2023;61:E0056223
- Caplan AS, Todd GC, Zhu Y, et al. Clinical course, antifungal susceptibility, and genomic sequencing of Trichophyton indotineae. JAMA Dermatol. 2024;160:701-709. doi:10.1001/jamadermatol.2024.1126
- Benedict K. Topical antifungal prescribing for Medicare Part D beneficiaries—United States, 2021. MMWR Morb Mortal Wkly Rep. 2024;73:1-5.
- Verma SB. Emergence of recalcitrant dermatophytosis in India. Lancet Infect Dis. 2018;18:718-719.
- Khurana A, Sharath S, Sardana K, et al. Clinico-mycological and therapeutic updates on cutaneous dermatophytic infections in the era of Trichophyton indotineae. J Am Acad Dermatol. 2024;91:315-323. doi:10.1016/j.jaad.2024.03.024
- Verma S. Steroid modified tinea. BMJ. 2017;356:j973.
- 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. 2022;158:1269-1278.
- Burmester A, Hipler UC, Uhrlaß S, et al. Indian Trichophyton mentagrophytes squalene epoxidase erg1 double mutants show high proportion of combined fluconazole and terbinafine resistance. Mycoses. 2020;63:1175-1180.
- Bhuiyan MSI, Verma SB, Illigner GM, et al. Trichophyton mentagrophytes ITS genotype VIII/Trichophyton indotineae infection and antifungal resistance in Bangladesh. J Fungi (Basel). 2024;10:768. doi:10.3390 /jof10110768
- Hay RJ. Chapter 82: superficial mycoses. In: Ryan ET, Hill DR, Solomon T, et al, eds. Hunter’s Tropical Medicine and Emerging Infectious Diseases. 10th ed. Elsevier; 2020:648-652.
- Gupta AK, Cooper EA, Wang T, et al. Detection of squalene epoxidase mutations in United States patients with onychomycosis: implications for management. J Invest Dermatol. 2023;143:2476-2483.E2477.
- Hwang JK, Bakotic WL, Gold JA, et al. Isolation of terbinafine-resistant Trichophyton rubrum from onychomycosis patients who failed treatment at an academic center in New York, United States. J Fungi. 2023;9:710.
- Gu D, Hatch M, Ghannoum M, et al. Treatment-resistant dermatophytosis: a representative case highlighting an emerging public health threat. JAAD Case Rep. 2020;6:1153-1155.
- Jabet A, Dellière S, Seang S, et al. Sexually transmitted Trichophyton mentagrophytes genotype VII infection among men who have sex with men. Emerg Infect Dis. 2023;29:1411-1414.
- Zucker J, Caplan AS, Gunaratne SH, et al. Notes from the field: Trichophyton mentagrophytes genotype VII—New York City, April-July 2024. MMWR Morb Mortal Wkly Rep. 2024;73:985-988.
- Jabet A, Bérot V, Chiarabini T, et al. Trichophyton mentagrophytes ITS genotype VII infections among men who have sex with men in France: an ongoing phenomenon. J Eur Acad Dermatol Venereol. 2025;39:407-415.
- Caplan AS, Gold JA, Smith DJ, et al. Improving antifungal stewardship in dermatology in an era of emerging dermatophyte resistance. JAAD International. 2024;15:168-169.
- Elewski B. A call for antifungal stewardship. Br J Dermatol. 2020; 183:798-799.
- Gold JAW, Benedict K, Caplan AS, et al. High rates of potentially unnecessary topical antifungal prescribing in a large commercial health insurance claims database, United States. J Am Acad Dermatol. 2025:S0190-9622(25)00098-2. doi:10.1016/j.jaad.2025.01.022
- Yadgar RJ, Bhatia N, Friedman A. Cutaneous fungal infections are commonly misdiagnosed: a survey-based study. J Am Acad Dermatol. 2017;76:562-563.
- Flint ND, Rhoads JLW, Carlisle R, et al. The continued inappropriate use and overuse of combination topical clotrimazole-betamethasone. Dermatol Online J. 2021;27. doi:10.5070/D327854686
- Currie DW, Caplan AS, Benedict K, et al. Prescribing of clotrimazolebetamethasone dipropionate, a topical combination corticosteroidantifungal product, for Medicare part D beneficiaries, United States, 2016–2022. Antimicrob Steward Healthc Epidemiol. 2024;4:E174.
- Gold JA, Caplan AS, Benedict K, et al. Clotrimazole-betamethasone dipropionate prescribing for nonfungal skin conditions. JAMA Network Open. 2024;7:E2411721-E2411721.
Worldwide, it is estimated that up to 1 in 5 individuals will experience a dermatophyte infection (commonly called ringworm or tinea infection) in their lifetime.1 Historically, dermatophyte infections have been considered relatively minor conditions usually treated with short courses of topical antifungals.2 Oral antifungals historically were needed only for patients with nail or hair shaft infections or extensive cutaneous fungal infections, which typically occurred in immunosuppressed patients.2 However, the landscape is changing rapidly due to the global emergence of severe dermatophyte infections that frequently are resistant to first-line antifungal medications.3-5 In this article, we aimed to review the epidemiology of emerging dermatophyte infections and provide dermatologists with information needed for effective diagnosis and management.
Emergence of Trichophyton indotineae
In recent decades, public health officials and dermatologists have noted with concern the spread of the recently emerged dermatophyte species Trichophyton indotineae in South Asia.3,6 This species (previously known as Trichophyton mentagrophytes genotype VIII) usually is transmitted from person to person, either through direct skin-to-skin contact or by fomites.4,6 Potential sexual transmission of T indotineae infections also has been reported,7 and it is possible that animals may serve as reservoirs for this pathogen, although there are no known reports of direct spread from animals to humans.8,9 Major outbreaks of T indotineae are ongoing in South Asia, and cases have been documented in 6 continents.10-12 In the United States, most but not all cases have occurred in immigrants from or recently returned travelers to South Asia.6,13 The emergence and spread of T indotineae is hypothesized to be promoted by the misuse and overuse of topical antifungal products, particularly those containing combinations of potent corticosteroids with other antimicrobial drugs.14,15
Cutaneous manifestations of T indotineae infections tend to cover large body surface areas, recur frequently, and pose substantial treatment challenges.6,13,16 Several clinical presentations have been documented, including erythematous, scaly concentric plaques; papulosquamous lesions; pustular forms; and corticosteroid-modified disease (Figure 1).6,16 Affected patients seldom are immunocompromised and often have a history of multiple failed courses of topical or oral antifungals, including oral terbinafine.13 Many also have been prescribed topical corticosteroids or have used over-the-counter topical corticosteroids, which worsen the rash.17
Direct microscopy with potassium hydroxide could be used to confirm the diagnosis of dermatophyte infection, but it does not distinguish T indotineae from other dermatophyte species.2,6 Importantly, culture-based testing usually will misidentify T indotineae as other Trichophyton species such as the more common T mentagrophytes or Trichophyton interdigitale. Definitive identification of T indotineae requires advanced molecular techniques that are available only at select laboratories.6 Unfortunately, availability of such testing is limited (Table), and results may take several weeks; therefore, it is suggested that dermatologists who suspect T indotineae infections based on the patient’s history and clinical presentation begin antifungal treatment after confirmation of dermatophyte infection but not wait for definitive confirmation of the causative organism.16
Itraconazole is considered the first-line therapy for T indotineae infection, as terbinafine usually is ineffective due to mutations in the squalene epoxidase gene.16 Dermatologists should be aware that itraconazole is available in different formulations that can affect absorption. The oral solution has greater bioavailability and should be taken on an empty stomach, whereas the capsules are required to be taken with food for effective absorption; the capsules also should be taken with an acidic beverage such as orange juice. Dermatologists should carefully assess for drug-drug interactions when prescribing itraconazole, given its extensive interaction profile with numerous other medications. Patients may require treatment with itraconazole (100 mg/d or 200 mg/d) for a minimum of 6 to 8 weeks until complete clearance has been achieved and ideally a negative potassium hydroxide preparation of skin scrapings has been obtained. A longer treatment period (eg, ≥3 months) frequently is needed, and relapses are common.6,16,18 Regular follow-up is needed to monitor for infection clearance and recurrences. It is important to note that cases of itraconazole resistance have been reported, although this currently appears to be uncommon.19,20
Other Emerging Dermatophytes to Watch
Trichophyton rubrum is the most common cause of dermatophyte infections among humans,21 and cases of terbinafine-resistant T rubrum infections have been reported increasingly in the United States and Canada.5,22-24 Onychomycosis caused by terbinafine-resistant T rubrum has been documented, and patients may have infections that do not respond to terbinafine given at the standard dose and duration.22,23 Case reports have indicated successful treatment using itraconazole 200 mg/d and posaconazole 300 mg/d.5,23
Trichophyton mentagrophytes genotype VII (TMVII) is an emerging dermatophyte that recently has been reported as a cause of sexually transmitted dermatophyte infections in Europe and the United States primarily affecting men who have sex with men.25-27 Patients may present with pruritic, annular, scaly patches and plaques involving the trunk, groin, genital region, or face (Figure 2). Although closely related to T indotineae, TMVII differs in that it more often affects the genital region, generally is susceptible to terbinafine, and in the United States and Europe usually is not related to travel or immigration involving South Asia.26 Although TMVII has not been associated with antifungal resistance, awareness among dermatologists is important because patients may experience inflamed, painful, and persistent rashes that can lead to secondary bacterial infection or scarring, and physicians might mistake it for mimics including eczema or psoriasis.25,26
Importance of Judicious Antifungal Use
Optimizing the use of antifungals is critical to improving patient outcomes and preserving available treatment options.28,29 A retrospective analysis of commercial health insurance data estimated that topical antifungal prescriptions were potentially unnecessary for more than half of the more than 560,000 patients who were prescribed these medications in 2023. In this study, it also was observed that only 16% of patients prescribed a topical antifungal had received diagnostic testing, with low rates across specialties.30 This is concerning because even among board-certified dermatologists, incorrect diagnosis of suspected fungal skin infections can occur; in one survey-based study of board-certified dermatologists who were presented with dermatomycosis images, respondents categorized cases with greater than 75% accuracy in only 31% (4/13) of instances.31 Clotrimazole-betamethasone is among the most commonly prescribed topical antifungals in the United States,14,32 and 2 recent retrospective analyses highlighted that the majority of patients prescribed this medication did not receive any fungal diagnostic testing.33,34
Final Thoughts
In an era of emerging antifungal-resistant dermatophyte infections, it is important for dermatologists to educate nondermatologists about the importance of using diagnostic testing for suspected dermatophyte infections.14,28 Dermatologists also can educate nondermatologist colleagues on the importance of avoiding the use of topical combination antifungal/corticosteroid medications and referring for dermatologic evaluation when diagnoses are uncertain.33,34 Strategies for education by dermatologists could include giving workshops, creating educational materials, and fostering open communication about optimal treatment practices and referral parameters for suspected dermatophyte infections.
Worldwide, it is estimated that up to 1 in 5 individuals will experience a dermatophyte infection (commonly called ringworm or tinea infection) in their lifetime.1 Historically, dermatophyte infections have been considered relatively minor conditions usually treated with short courses of topical antifungals.2 Oral antifungals historically were needed only for patients with nail or hair shaft infections or extensive cutaneous fungal infections, which typically occurred in immunosuppressed patients.2 However, the landscape is changing rapidly due to the global emergence of severe dermatophyte infections that frequently are resistant to first-line antifungal medications.3-5 In this article, we aimed to review the epidemiology of emerging dermatophyte infections and provide dermatologists with information needed for effective diagnosis and management.
Emergence of Trichophyton indotineae
In recent decades, public health officials and dermatologists have noted with concern the spread of the recently emerged dermatophyte species Trichophyton indotineae in South Asia.3,6 This species (previously known as Trichophyton mentagrophytes genotype VIII) usually is transmitted from person to person, either through direct skin-to-skin contact or by fomites.4,6 Potential sexual transmission of T indotineae infections also has been reported,7 and it is possible that animals may serve as reservoirs for this pathogen, although there are no known reports of direct spread from animals to humans.8,9 Major outbreaks of T indotineae are ongoing in South Asia, and cases have been documented in 6 continents.10-12 In the United States, most but not all cases have occurred in immigrants from or recently returned travelers to South Asia.6,13 The emergence and spread of T indotineae is hypothesized to be promoted by the misuse and overuse of topical antifungal products, particularly those containing combinations of potent corticosteroids with other antimicrobial drugs.14,15
Cutaneous manifestations of T indotineae infections tend to cover large body surface areas, recur frequently, and pose substantial treatment challenges.6,13,16 Several clinical presentations have been documented, including erythematous, scaly concentric plaques; papulosquamous lesions; pustular forms; and corticosteroid-modified disease (Figure 1).6,16 Affected patients seldom are immunocompromised and often have a history of multiple failed courses of topical or oral antifungals, including oral terbinafine.13 Many also have been prescribed topical corticosteroids or have used over-the-counter topical corticosteroids, which worsen the rash.17
Direct microscopy with potassium hydroxide could be used to confirm the diagnosis of dermatophyte infection, but it does not distinguish T indotineae from other dermatophyte species.2,6 Importantly, culture-based testing usually will misidentify T indotineae as other Trichophyton species such as the more common T mentagrophytes or Trichophyton interdigitale. Definitive identification of T indotineae requires advanced molecular techniques that are available only at select laboratories.6 Unfortunately, availability of such testing is limited (Table), and results may take several weeks; therefore, it is suggested that dermatologists who suspect T indotineae infections based on the patient’s history and clinical presentation begin antifungal treatment after confirmation of dermatophyte infection but not wait for definitive confirmation of the causative organism.16
Itraconazole is considered the first-line therapy for T indotineae infection, as terbinafine usually is ineffective due to mutations in the squalene epoxidase gene.16 Dermatologists should be aware that itraconazole is available in different formulations that can affect absorption. The oral solution has greater bioavailability and should be taken on an empty stomach, whereas the capsules are required to be taken with food for effective absorption; the capsules also should be taken with an acidic beverage such as orange juice. Dermatologists should carefully assess for drug-drug interactions when prescribing itraconazole, given its extensive interaction profile with numerous other medications. Patients may require treatment with itraconazole (100 mg/d or 200 mg/d) for a minimum of 6 to 8 weeks until complete clearance has been achieved and ideally a negative potassium hydroxide preparation of skin scrapings has been obtained. A longer treatment period (eg, ≥3 months) frequently is needed, and relapses are common.6,16,18 Regular follow-up is needed to monitor for infection clearance and recurrences. It is important to note that cases of itraconazole resistance have been reported, although this currently appears to be uncommon.19,20
Other Emerging Dermatophytes to Watch
Trichophyton rubrum is the most common cause of dermatophyte infections among humans,21 and cases of terbinafine-resistant T rubrum infections have been reported increasingly in the United States and Canada.5,22-24 Onychomycosis caused by terbinafine-resistant T rubrum has been documented, and patients may have infections that do not respond to terbinafine given at the standard dose and duration.22,23 Case reports have indicated successful treatment using itraconazole 200 mg/d and posaconazole 300 mg/d.5,23
Trichophyton mentagrophytes genotype VII (TMVII) is an emerging dermatophyte that recently has been reported as a cause of sexually transmitted dermatophyte infections in Europe and the United States primarily affecting men who have sex with men.25-27 Patients may present with pruritic, annular, scaly patches and plaques involving the trunk, groin, genital region, or face (Figure 2). Although closely related to T indotineae, TMVII differs in that it more often affects the genital region, generally is susceptible to terbinafine, and in the United States and Europe usually is not related to travel or immigration involving South Asia.26 Although TMVII has not been associated with antifungal resistance, awareness among dermatologists is important because patients may experience inflamed, painful, and persistent rashes that can lead to secondary bacterial infection or scarring, and physicians might mistake it for mimics including eczema or psoriasis.25,26
Importance of Judicious Antifungal Use
Optimizing the use of antifungals is critical to improving patient outcomes and preserving available treatment options.28,29 A retrospective analysis of commercial health insurance data estimated that topical antifungal prescriptions were potentially unnecessary for more than half of the more than 560,000 patients who were prescribed these medications in 2023. In this study, it also was observed that only 16% of patients prescribed a topical antifungal had received diagnostic testing, with low rates across specialties.30 This is concerning because even among board-certified dermatologists, incorrect diagnosis of suspected fungal skin infections can occur; in one survey-based study of board-certified dermatologists who were presented with dermatomycosis images, respondents categorized cases with greater than 75% accuracy in only 31% (4/13) of instances.31 Clotrimazole-betamethasone is among the most commonly prescribed topical antifungals in the United States,14,32 and 2 recent retrospective analyses highlighted that the majority of patients prescribed this medication did not receive any fungal diagnostic testing.33,34
Final Thoughts
In an era of emerging antifungal-resistant dermatophyte infections, it is important for dermatologists to educate nondermatologists about the importance of using diagnostic testing for suspected dermatophyte infections.14,28 Dermatologists also can educate nondermatologist colleagues on the importance of avoiding the use of topical combination antifungal/corticosteroid medications and referring for dermatologic evaluation when diagnoses are uncertain.33,34 Strategies for education by dermatologists could include giving workshops, creating educational materials, and fostering open communication about optimal treatment practices and referral parameters for suspected dermatophyte infections.
- Noble SL, Forbes RC, Stamm PL. Diagnosis and management of common tinea infections. Am Fam Physician. 1998;58:163-174, 177-168.
- Ely JW, Rosenfeld S, Seabury Stone M. Diagnosis and management of tinea infections. Am Fam Physician. 2014;90:702-710.
- Uhrlaß S, Verma SB, Gräser Y, et al. Trichophyton indotineae—an emerging pathogen causing recalcitrant dermatophytoses in India and worldwide—a multidimensional perspective. J Fungi (Basel). 2022;8:757. doi:10.3390/jof8070757
- Verma SB, Panda S, Nenoff P, et al. The unprecedented epidemic-like scenario of dermatophytosis in India: I. epidemiology, risk factors and clinical features. Indian J Dermatol Venereol Leprol. 2021;87:154-175.
- Chen E, Ghannoum M, Elewski BE. Treatment]resistant tinea corporis, a potential public health issue. Br J Dermatol. 2021;184:164-165.
- Caplan AS. Notes from the field: first reported US cases of tinea caused by Trichophyton indotineae—New York City, December 2021–March 2023. MMWR Morbidity and Mortality Weekly Report. 2023;72:536-537. doi:10.15585/mmwr.mm7219a4
- Spivack S, Gold JA, Lockhart SR, et al. Potential sexual transmission of antifungal-resistant Trichophyton indotineae. Emerg Infect Dis. 2024;30:807.
- Jabet A, Brun S, Normand AC, et al. Extensive dermatophytosis caused by terbinafine-resistant Trichophyton indotineae, France. Emerg Infect Dis. 2022;28:229-233.
- Thakur S, Spruijtenburg B, Abhishek, et al. Whole genome sequence analysis of terbinafine resistant and susceptible Trichophyton isolates from human and animal origin. Mycopathologia. 2025;190:13.
- Lockhart SR, Chowdhary A, Gold JA. The rapid emergence of antifungal-resistant human-pathogenic fungi. Nat Rev Microbiol. 2023;21:818-832.
- Mosam A, Shuping L, Naicker S, et al. A case of antifungal-resistant ringworm infection in KwaZulu-Natal Province, South Africa, caused by Trichophyton indotineae. Public Health Bulletin South Africa. Accessed April 4, 2025. https://www.phbsa.ac.za/wp-content/uploads/2023/12PHBSA-Ringworm-Article-2023.pdf
- Cañete-Gibas CF, Mele J, Patterson HP, et al. Terbinafine-resistant dermatophytes and the presence of Trichophyton indotineae in North America. J Clin Microbiol. 2023;61:E0056223
- Caplan AS, Todd GC, Zhu Y, et al. Clinical course, antifungal susceptibility, and genomic sequencing of Trichophyton indotineae. JAMA Dermatol. 2024;160:701-709. doi:10.1001/jamadermatol.2024.1126
- Benedict K. Topical antifungal prescribing for Medicare Part D beneficiaries—United States, 2021. MMWR Morb Mortal Wkly Rep. 2024;73:1-5.
- Verma SB. Emergence of recalcitrant dermatophytosis in India. Lancet Infect Dis. 2018;18:718-719.
- Khurana A, Sharath S, Sardana K, et al. Clinico-mycological and therapeutic updates on cutaneous dermatophytic infections in the era of Trichophyton indotineae. J Am Acad Dermatol. 2024;91:315-323. doi:10.1016/j.jaad.2024.03.024
- Verma S. Steroid modified tinea. BMJ. 2017;356:j973.
- 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. 2022;158:1269-1278.
- Burmester A, Hipler UC, Uhrlaß S, et al. Indian Trichophyton mentagrophytes squalene epoxidase erg1 double mutants show high proportion of combined fluconazole and terbinafine resistance. Mycoses. 2020;63:1175-1180.
- Bhuiyan MSI, Verma SB, Illigner GM, et al. Trichophyton mentagrophytes ITS genotype VIII/Trichophyton indotineae infection and antifungal resistance in Bangladesh. J Fungi (Basel). 2024;10:768. doi:10.3390 /jof10110768
- Hay RJ. Chapter 82: superficial mycoses. In: Ryan ET, Hill DR, Solomon T, et al, eds. Hunter’s Tropical Medicine and Emerging Infectious Diseases. 10th ed. Elsevier; 2020:648-652.
- Gupta AK, Cooper EA, Wang T, et al. Detection of squalene epoxidase mutations in United States patients with onychomycosis: implications for management. J Invest Dermatol. 2023;143:2476-2483.E2477.
- Hwang JK, Bakotic WL, Gold JA, et al. Isolation of terbinafine-resistant Trichophyton rubrum from onychomycosis patients who failed treatment at an academic center in New York, United States. J Fungi. 2023;9:710.
- Gu D, Hatch M, Ghannoum M, et al. Treatment-resistant dermatophytosis: a representative case highlighting an emerging public health threat. JAAD Case Rep. 2020;6:1153-1155.
- Jabet A, Dellière S, Seang S, et al. Sexually transmitted Trichophyton mentagrophytes genotype VII infection among men who have sex with men. Emerg Infect Dis. 2023;29:1411-1414.
- Zucker J, Caplan AS, Gunaratne SH, et al. Notes from the field: Trichophyton mentagrophytes genotype VII—New York City, April-July 2024. MMWR Morb Mortal Wkly Rep. 2024;73:985-988.
- Jabet A, Bérot V, Chiarabini T, et al. Trichophyton mentagrophytes ITS genotype VII infections among men who have sex with men in France: an ongoing phenomenon. J Eur Acad Dermatol Venereol. 2025;39:407-415.
- Caplan AS, Gold JA, Smith DJ, et al. Improving antifungal stewardship in dermatology in an era of emerging dermatophyte resistance. JAAD International. 2024;15:168-169.
- Elewski B. A call for antifungal stewardship. Br J Dermatol. 2020; 183:798-799.
- Gold JAW, Benedict K, Caplan AS, et al. High rates of potentially unnecessary topical antifungal prescribing in a large commercial health insurance claims database, United States. J Am Acad Dermatol. 2025:S0190-9622(25)00098-2. doi:10.1016/j.jaad.2025.01.022
- Yadgar RJ, Bhatia N, Friedman A. Cutaneous fungal infections are commonly misdiagnosed: a survey-based study. J Am Acad Dermatol. 2017;76:562-563.
- Flint ND, Rhoads JLW, Carlisle R, et al. The continued inappropriate use and overuse of combination topical clotrimazole-betamethasone. Dermatol Online J. 2021;27. doi:10.5070/D327854686
- Currie DW, Caplan AS, Benedict K, et al. Prescribing of clotrimazolebetamethasone dipropionate, a topical combination corticosteroidantifungal product, for Medicare part D beneficiaries, United States, 2016–2022. Antimicrob Steward Healthc Epidemiol. 2024;4:E174.
- Gold JA, Caplan AS, Benedict K, et al. Clotrimazole-betamethasone dipropionate prescribing for nonfungal skin conditions. JAMA Network Open. 2024;7:E2411721-E2411721.
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- Hay RJ. Chapter 82: superficial mycoses. In: Ryan ET, Hill DR, Solomon T, et al, eds. Hunter’s Tropical Medicine and Emerging Infectious Diseases. 10th ed. Elsevier; 2020:648-652.
- Gupta AK, Cooper EA, Wang T, et al. Detection of squalene epoxidase mutations in United States patients with onychomycosis: implications for management. J Invest Dermatol. 2023;143:2476-2483.E2477.
- Hwang JK, Bakotic WL, Gold JA, et al. Isolation of terbinafine-resistant Trichophyton rubrum from onychomycosis patients who failed treatment at an academic center in New York, United States. J Fungi. 2023;9:710.
- Gu D, Hatch M, Ghannoum M, et al. Treatment-resistant dermatophytosis: a representative case highlighting an emerging public health threat. JAAD Case Rep. 2020;6:1153-1155.
- Jabet A, Dellière S, Seang S, et al. Sexually transmitted Trichophyton mentagrophytes genotype VII infection among men who have sex with men. Emerg Infect Dis. 2023;29:1411-1414.
- Zucker J, Caplan AS, Gunaratne SH, et al. Notes from the field: Trichophyton mentagrophytes genotype VII—New York City, April-July 2024. MMWR Morb Mortal Wkly Rep. 2024;73:985-988.
- Jabet A, Bérot V, Chiarabini T, et al. Trichophyton mentagrophytes ITS genotype VII infections among men who have sex with men in France: an ongoing phenomenon. J Eur Acad Dermatol Venereol. 2025;39:407-415.
- Caplan AS, Gold JA, Smith DJ, et al. Improving antifungal stewardship in dermatology in an era of emerging dermatophyte resistance. JAAD International. 2024;15:168-169.
- Elewski B. A call for antifungal stewardship. Br J Dermatol. 2020; 183:798-799.
- Gold JAW, Benedict K, Caplan AS, et al. High rates of potentially unnecessary topical antifungal prescribing in a large commercial health insurance claims database, United States. J Am Acad Dermatol. 2025:S0190-9622(25)00098-2. doi:10.1016/j.jaad.2025.01.022
- Yadgar RJ, Bhatia N, Friedman A. Cutaneous fungal infections are commonly misdiagnosed: a survey-based study. J Am Acad Dermatol. 2017;76:562-563.
- Flint ND, Rhoads JLW, Carlisle R, et al. The continued inappropriate use and overuse of combination topical clotrimazole-betamethasone. Dermatol Online J. 2021;27. doi:10.5070/D327854686
- Currie DW, Caplan AS, Benedict K, et al. Prescribing of clotrimazolebetamethasone dipropionate, a topical combination corticosteroidantifungal product, for Medicare part D beneficiaries, United States, 2016–2022. Antimicrob Steward Healthc Epidemiol. 2024;4:E174.
- Gold JA, Caplan AS, Benedict K, et al. Clotrimazole-betamethasone dipropionate prescribing for nonfungal skin conditions. JAMA Network Open. 2024;7:E2411721-E2411721.
The Rise of Antifungal-Resistant Dermatophyte Infections: What Dermatologists Need to Know
The Rise of Antifungal-Resistant Dermatophyte Infections: What Dermatologists Need to Know
PRACTICE POINTS
- Recently emerged dermatophyte species pose a global public health concern because of infection severity, frequent resistance to terbinafine, and easy person-to-person transmission.
- Prolonged itraconazole therapy is considered the firstline treatment for infections caused by Trichophyton indotineae, a globally emerging and frequently terbinafine-resistant dermatophyte.
- Dermatologists can educate nondermatologists on the importance of mycologic confirmation and avoidance of the use of topical antifungal/ corticosteroid products, which are hypothesized to contribute to emergence and spread of resistance.
