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• Posted June 5, 2024

Experts Warn of Drug-Resistant Jock Itch, Athlete's Foot

Drug-resistant fungal infections are appearing in the United States, resulting in highly contagious and tough-to-treat cases of ringworm, also known as jock itch or athlete's foot, experts warn in a pair of reports.

The two fungi reported are among a group that cause skin rashes of the face, limbs, groin and feet, researchers said.

Unfortunately, the rashes can look very different from the neat, regular circles seen in most forms of ringworm, researchers said. They might be confused with eczema, and go for months without proper treatment.

A man in his 30s developed such a rash on his penis, buttocks and limbs after returning home to New York City from a trip to England, Greece and California, according to a report published June 5 in the journal JAMA Dermatology.

Genetic tests revealed the infection was caused by a sexually transmitted form of ringworm called Trichophyton mentagrophytes type VII. The man told doctors he'd had sex with multiple male partners during his travels, none of whom reported similar skin issues.

"Healthcare providers should be aware that Trichophyton mentagrophytes type VII is the latest in a group of severe skin infections to have now reached the United States,"said lead author Dr. Avrom Caplan, an assistant professor of dermatology at NYU Grossman School of Medicine in New York City.

Infections caused by that fungus are difficult to treat and can take months to clear up, senior researcher Dr. John Zampella, an associate professor of dermatology at NYU Grossman, said in a university news release.

The second report in JAMA Dermatology involved 11 men and women treated for ringworm in New York City hospitals in 2022 and 2023.

Their infections involved Trichophyton indotineae, a fungal infection widespread in India that was first confirmed in the United States last year.

Seven of the patients had received standard doses of the antifungal terbinafine -- brand name Lamasil -- for 14 to 42 days, with no improvement in their rashes.

DNA analysis found several variations in the fungus' genetic code that prevent terbinafine from hooking onto fungal cells and poking holes in their protective membranes, researchers said. This could explain why the drug failed to fight the infection.

Seven patients were treated with another antifungal called itraconazole, and three recovered entirely while two improved, researchers said.

Unfortunately, itraconazole can interfere with many medications and can cause nausea, diarrhea and other side effects that make it tough to stay on for long, Caplan said.

"These findings offer new insight into how some of the fungal skin infections spreading from South Asia can evade our go-to therapies,"said Caplan. "Beyond learning to recognize their misleading signs, physicians will need to ensure their treatment addresses each patient's quality-of-life needs."

Leading fungi experts around the United States and internationally are working to expand research efforts and track emerging cases, Caplan said.

More information

The U.S. Centers for Disease Control and Prevention have more about ringworm.

SOURCE: NYU Langone, news release, June 5, 2024