Antibiofilm activity of terbinafine, itraconazole and their combination against Sporothrix brasiliensis yeast-like form’s biofilms

Sporothrix brasiliensis biofilms represent a challenge in the treatment of sporotrichosis due to their structural complexity and antifungal resistance. This study evaluated the efficacy of terbinafine (TERB) and itraconazole (ITZ), and their synergism against biofilms of yeast-like forms of S. brasiliensis. Seven clinical strains were analyzed for biofilm formation and structural alterations using spectrophotometry, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). The treatment in early-stage biofilms (3 hours) exhibited greater susceptibility to ITZ, whereas mature biofilms (144 hours) responded better to TERB. Statistical analysis confirmed significant differences among treatments (p < 0.016) and a dose-dependent effect, although no considerable synergistic interaction was observed between ITZ and TERB. CLSM and SEM analyses revealed reduced biofilm formation and adhesion, biofilm disorganization, and cellular morphological changes following exposure to antifungals, both individually and in combination. TERB was significantly more effective in eradicating mature biofilms than ITZ or the combination (p < 0.001). These findings reinforce the need for early intervention in sporotrichosis treatment and suggest that TERB may be a valuable alternative for biofilm-associated infections.