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• Posted January 11, 2024

Overuse of Antifungal Skin Meds Could Be Driving Drug-Resistant Disease

U.S. doctors are prescribing antifungal creams to patients with skin complaints at rates so high they could be contributing to the rise of drug-resistant infections, new research shows.

These are "severe antimicrobial-resistant superficial fungal infections, which have recently been detected in the United States," noted a team led by Jeremy Gold, a researcher at the U.S. Centers for Disease Control and Prevention.

One of the biggest emerging threats: Drug-resistant forms of ringworm (a form of dermatophytosis).

In Southeast Asia, major outbreaks of this itchy, circular rash have occurred that are not responding to either topical antifungal creams or pills.

Cases of ringworm resistant to drugs have also now been spotted in 11 U.S. states, Gold's team noted. This is leading to "patients experiencing extensive lesions and delays in diagnosis," the team said.

As is seen with the overuse of antibiotics, fungi naturally build up resistance to antifungal meds the more they are exposed to them. The CDC team believes that antifungal topical creams are being overprescribed.

Looking at 2021 Medicare Part D data, they found that 6.5 million prescriptions for creams containing antifungals, such as ketoconazole, nystatin and clotrimazole-betamethasone, were prescribed that year.

In sheer numbers, primary care doctors wrote the biggest percentage of these prescriptions, but dermatologists and podiatrists had much higher rates on a prescriptions-per-doctor basis.

One of the big issues, according to Gold's team, is that most doctors diagnose a skin condition simply by looking at it, a method that is "frequently incorrect," even among board-certified dermatologists.

"Confirmatory diagnostic testing" of a skin lesion beyond just looking at it is rarely done, they added.

A small percentage of physicians are prescribing antifungal drugs at exceedingly high rates. In 2021, "10% of antifungal prescribers prescribed nearly one half of these medications," Gold's group found.

The new study probably only captures a fraction of the overuse of antifungals, since "most topical antifungals can be purchased over the counter without a prescription," the researchers noted.

The high use of clotrimazole-betamethasone, in particular, is thought to be a big factor in the emergence of drug-resistant ringworm.

This drug (a combination of a steroid and an antifungal) can also "cause skin damage if applied to intertriginous areas," meaning areas where the skin folds onto itself, such as occurs around the groin, buttocks and armpits.

Long-term, extensive use of clotrimazole-betamethasone can also trigger hormonal problems, Gold's team said.

The bottom line, according to the CDC team: "Health care providers should be judicious in prescribing topical antifungals" for suspected fungal skin infections, and go beyond a visual diagnosis when possible.

Doctors should also try to "educate patients about the correct use of topical antifungals and combination antifungal-cortoicosteroids" to help reduce overprescribing and the danger of drug-resistant fungal disease, they added.

The findings were published in the Jan. 11 issue of the CDC journal Morbidity and Mortality Weekly Report.

More information

Find out more about ringworm at the Mayo Clinic.

SOURCE: Morbidity and Mortality Weekly Report, Jan. 11, 2024