US doctors are closely watching a rising concern: drug‑resistant fungi that can trigger ringworm in humans. The topic has been highlighted by two serious illness cases reported in New York and analyzed in a study released by a federal health agency in the United States. This case report reflects growing attention from public health authorities about the potential spread of resistant fungal infections across regions and populations. The study notes that the two patients were not linked to each other. One became ill in the summer of 2021 in the United States, while the other developed the infection in the summer of 2022 in Bangladesh, underscoring the global reach of evolving fungal threats.
Ringworm typically presents as a superficial skin infection, sometimes affecting hair and nails. In more rare instances, the fungus can invade deeper layers of skin or even spread to internal organs and the musculoskeletal system, creating a more challenging medical scenario. Without prompt treatment, ringworm infections may lead to secondary bacterial infections, complicating recovery and increasing the risk of complications. Public health researchers emphasize the importance of monitoring for early signs, seeking timely medical advice, and applying appropriate antifungal therapies to limit spread and reduce harm.
Initial laboratory work in these two cases suggested a familiar culprit, Trichophyton mentagrophytes, a fungus commonly associated with pets and known for its capacity to transfer between animals and humans. However, advanced genetic analysis revealed a different and more concerning identification: a relatively new fungal species named Trichophyton indotineae. This species carries mutations that reduce the effectiveness of certain first‑line antifungal medications, particularly terbinafine, which is widely used in tablet form to treat skin and nail infections caused by fungi. The presence of resistance mutations in T. indotineae signals a potential shift in how clinicians approach treatment, especially when standard therapies fail to produce expected results.
Terbinafine resistance was first recognized in an Indian production of a related fungus in 2014 and later documented in Europe in 2020. The discovery of terbinafine resistance in the two recent United States cases raises concerns about the spread of this resistant strain to new geographic areas and patient groups. The evolving resistance pattern suggests that the fungus may be moving beyond its traditional reservoirs, challenging clinicians to reassess diagnostic approaches and consider alternative antifungal strategies early in the course of treatment. Public health officials are calling for heightened surveillance, better laboratory capabilities for rapid fungus identification, and guidance on when to pivot to different medications to optimize outcomes for patients with stubborn infections. It also highlights the importance of responsible antifungal use to slow the development of resistance and preserve the effectiveness of available therapies for skin and nail infections.