CDC Reports Two Cases of Drug-Resistant Ringworm

The Centers for Disease Control and Prevention is alerting clinicians to be on the lookout for a severe antifungal-resistant form of tinea, as it was recently detected in two patients in New York.

Tinea, or ringworm, one of the most common fungal infections, is responsible for almost 5 million outpatient visits and 690 hospitalizations annually, according to the CDC.

Over the past 10 years, severe, antifungal-resistant tinea has spread in South Asia, in part because of the rise of a new dermatophyte species known as Trichophyton indotineae, wrote the authors of a report on the two patients with the drug-resistant strain. This epidemic “has likely been driven by misuse and overuse of topical antifungals and corticosteroids,” added the authors, in Morbidity and Mortality Weekly Report.

The cases were detected by a New York City dermatologist. In the first case, a 28-year-old woman developed a widespread pruritic eruption in the summer of 2021. She did not consult a dermatologist until December, when she was in the third trimester of pregnancy. She had large, annular, scaly, pruritic plaques on her neck, abdomen, pubic region, and buttocks, but had no underlying medical conditions, no known exposures to someone with a similar rash, and no recent international travel history.

After she gave birth in January, she started oral terbinafine therapy but had no improvement after 2 weeks. Clinicians administered a 4-week course of itraconazole, which resolved the infection.

The second patient, a 47-year-old woman with no medical conditions, developed a rash while in Bangladesh in the summer of 2022. Other family members had a similar rash. She was treated with topical antifungal and steroid combination creams but had no resolution. Back in the United States, she was prescribed hydrocortisone 2.5% ointment and diphenhydramine, clotrimazole cream, and terbinafine cream in three successive emergency department visits. In December 2022, dermatologists, observing widespread, discrete, scaly, annular, pruritic plaques on the thighs and buttocks, prescribed a 4-week course of oral terbinafine. When the rash did not resolve, she was given 4 weeks of griseofulvin. The rash persisted, although there was 80% improvement. Clinicians are now considering itraconazole. The woman’s son and husband are also being evaluated, as they have similar rashes.

In both cases, skin culture isolates were initially identified as Trichophyton mentagrophytes. Further analysis at the New York State Department of Health’s lab, using Sanger sequencing of the internal transcribed spacer region of the ribosomal gene, followed by phylogenetic analysis, identified the isolates as T. indotineae.

The authors note that culture-based techniques used by most clinical laboratories typically misidentify T. indotineae as T. mentagrophytes or T. interdigitale. Genomic sequencing must be used to properly identify T. indotineae, they wrote.

Clinicians should consider T. indotineae in patients with widespread ringworm, especially if they do not improve with topical antifungals or oral terbinafine, said the authors. If T. indotineae is suspected, state or local public health departments can direct clinicians to testing.

The authors report no relevant financial relationships.

This article originally appeared on, part of the Medscape Professional Network.

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