Drug-resistantdermatophytes
What you need to know
Dermatophytes are a group of fungi that infect the skin, hair, and nails and cause ringworm (tinea). These common, contagious infections are generally mild and often treated successfully with over-the-counter (OTC) topical antifungal medications.
Recently, some dermatophyte strains have developed resistance to antifungal treatments such as terbinafine, which is commonly used to treat ringworm. Drug-resistant dermatophyte infections can be more difficult to treat, may require longer or alternative therapies, and are more likely to recur. Two drug-resistant dermatophyte strains, Trichophyton indotineae and Trichophyton rubrum, can cause more severe infections, including in otherwise healthy people, making them an emerging public health concern.
What we know about resistance
Increasing numbers of drug-resistant dermatophyte infections have been reported globally, including in the United States, but the overall burden is not well understood. Estimating the number of cases is challenging because infections may be misdiagnosed or unrecognized by healthcare providers. In addition, identifying resistance requires specialized testing that is not widely available, and dermatophyte infections are not nationally reportable in the United States, which limits the ability to track cases and understand the full burden.
Several factors can contribute to the emergence and spread of drug-resistant dermatophytes: inappropriate prescribing of antifungal drugs, use of topical antifungal-corticosteroid combination products, and misuse of OTC topical antifungals.
What CDC is doing
Although surveillance for drug-resistant dermatophyte infections in the United States is currently limited, CDC is working with state and local partners to improve detection and management while better understanding disease burden. These efforts include expanding laboratory capacity to identify resistant dermatophytes and conduct antifungal susceptibility testing through CDC's Antimicrobial Resistance Laboratory Network. CDC is also working to increase awareness among the public, clinicians, and public health professionals of drug-resistant dermatophytes and promote appropriate antifungal use.