Introduction: Dermatophytosis is the most common fungal infection encountered by primary care providers and outpatient physicians. In recent years, new patient populations with chronic infections - accompanied by a history of recurrences and relapses - presenting with unusual or severe manifestations have been reported worldwide. This is broadly referred to as recalcitrant dermatophytosis.
Areas covered: Through an electronic literature search spanning the last 25 years, we discuss systemic treatment options for recalcitrant dermatophytosis, including conventional terbinafine and itraconazole treatments, either alone or in combination with topicals. Dosing strategies and treatment durations are summarized along with potential reasons for treatment failure. There is mounting evidence suggesting that dermatophyte resistance is a significant cause of terbinafine nonresponse, making itraconazole the preferred first-line treatment. However, pharmacokinetic variability may cause sub-therapeutic exposure and induce resistance to itraconazole. In some instances, super-bioavailable itraconazole may be a consideration. Corticosteroids should be strictly avoided.
Expert opinion: The current literature is limited by case reports and small case series. Newer triazoles and ketoconazole have been reported as drugs of last resort. Increased advocacy and collaboration are needed to standardize the management of recalcitrant dermatophytosis including antifungal susceptibility testing, especially concerning special populations such as pregnant individuals and children.
Keywords: Tinea; Trichophyton infection; drug resistance; fungal; persistent infection; tinea corporis; tinea cruris.
Fungal infections of the skin, hair, and nails are becoming a healthcare challenge worldwide. Despite being commonly misperceived as a mild infection that can resolve on its own, there is a new wave of patients developing persistent infections that can last for more than 6 months with episodes of recurrences, despite receiving treatment. While the exact cause of this problem is unknown, it is speculated that over-the-counter medications containing steroids, and misdiagnosis without lab testing, can exacerbate the infection. This trend is also associated with a newly evolved pathogen, known as Trichophyton indotineae, which was first reported in the Indian subcontinent and is now spreading globally.Here, we summarize oral treatment options for these infections. The most commonly prescribed medications are terbinafine and itraconazole. However, with concerns about resistance to terbinafine, itraconazole is now preferred as the first-line treatment. Nonetheless, itraconazole is complicated by its erratic drug absorption, which can lead to nonresponse or resistance development. A newer itraconazole formulation with improved absorption (super-bioavailable itraconazole) is being investigated.When the infection becomes resistant to both terbinafine and itraconazole, physicians are often left with no good treatment options. As a result, off-label medications like ketoconazole, voriconazole, and posaconazole are sometimes used, even though there is limited evidence supported their efficacy. To solve this challenge, it is important to conduct further clinical trials and form cross-national collaboration to optimize management. This is especially important for treating children and pregnant individuals, as the toxicity of antifungal medications is a concern.