Emergence of difficult-to-treat lymphocutaneous sporotrichosis? Analysis based on three cases with high and low MIC Sporothrix brasiliensis isolates.

Abstract

Sporotrichosis, caused by a Sporothrix schenckii complex species, is historically viewed as an easily manageable mycosis. However, the current zoonotic epidemic in Brazil due to the more virulent Sporothrix brasiliensis poses some challenges. We describe three cases of lymphocutaneous sporotrichosis (LC) in non-immunocompromised patients, which proved refractory to standard treatment, and suggest that closer epidemic surveillance would be advisable to detect whether more difficult-to-treat cases are --emerging. All cases required prolonged treatment, escalating doses, and therapeutic changes for resolution. Patients' isolates were molecularly identified as S. brasiliensis. Antifungal susceptibility testing (AST) revealed high itraconazole MICs in two of the three isolates. Management required high-dose itraconazole (400 mg/day) in two cases and Amphotericin B in one. These cases challenge the perception of sporotrichosis as an always easily treatable disease. The difficulties observed may be linked to the increased S. brasiliensis virulence, the emergence of drug-resistant strains, and/or the rise in severe and atypical presentations. Lack of standardized protocols for refractory cases complicates effective management. These findings underscore the urgent need for enhanced epidemiological surveillance, efforts to isolate and perform AST on clinical strains, and standardization of treatment guidelines for patients failing initial therapy.