A recent report from the Centers for Disease Control and Prevention (CDC) has detailed the emergence of a novel dermatophyte species causing severe, antifungal-resistant tinea infections. The species, called Trichophyton indotineae, has caused an epidemic of infections in South Asia due to the misuse and overuse of topical antifungals and corticosteroids.
These infections are highly transmissible and are characterized by widespread, inflamed, pruritic plaques on the body, the crural fold, pubic region, and adjacent thigh, or the face.
The report describes two cases of T. indotineae infection in the United States. The first case involved a 28-year-old woman who developed a widespread pruritic eruption during the summer of 2021. She had no known exposures to a person with a similar rash and no recent international travel history.
Dermatologists diagnosed her with tinea and began treatment with oral terbinafine in January 2022, but her eruptions did not improve after 2 weeks of therapy. Terbinafine was discontinued, and she began treatment with itraconazole. The rash resolved completely after completing a 4-week course of itraconazole.
The second case involved a 47-year-old woman who developed a widespread, pruritic eruption in the summer of 2022 while in Bangladesh. She received treatment with topical antifungal and steroid combination creams and noted that several family members were experiencing similar eruptions. After returning to the United States, she visited an emergency department three times during the fall of 2022 and was prescribed various creams with no improvement.
In December 2022, dermatologists diagnosed her with tinea and began treatment with oral terbinafine, but her symptoms did not improve. She then received treatment with griseofulvin, resulting in approximately 80% improvement. Itraconazole therapy is being considered pending further evaluation given the recent confirmation of suspected T. indotineae infection.
The report highlights several important points. First, T. indotineae infections can occur in the United States, even in patients with no recent international travel history. Health care providers should consider T. indotineae infection in patients with widespread tinea, particularly when eruptions do not improve with first-line topical antifungal agents or oral terbinafine.
Second, culture-based identification techniques used by most clinical laboratories typically misidentify T. indotineae as other Trichophyton species, such as T. mentagrophytes or T. interdigitale. Correct identification requires genomic sequencing.
Third, successful treatment using oral itraconazole has been documented, but providers should be aware of challenges with itraconazole absorption, interactions with other drugs, the need for up to 12 weeks of therapy, and the emergence of triazole resistance.
Finally, antimicrobial stewardship efforts are essential to minimize the misuse and overuse of prescribed and over-the-counter antifungal drugs and corticosteroids, and health care providers can educate patients about strategies to prevent the spread of the dermatophytes that cause tinea. Public health surveillance efforts and increased testing could help detect and monitor the spread of T. indotineae.