Effect of Voriconazole on Biofilm of Filamentous Species Isolated from Keratitis

Abstract

Background: Biofilm formation is a vital feature of the pathogenesis in filamentous fungi. Objectives: Herein, we investigated in vitro antifungal pattern of biofilm of filamentous species keratitis isolates, and the effect of different concentrations of voriconazole on biofilm morphology changes using scanning electron microscopy. Methods: Here 25 ocular fungal isolates were included (Fusarium solani; (n = 15) and Aspergillus flavus; (n = 10). We determined the biofilm formation of isolates in terms of their susceptibilities to different antifungals on sessile cells. This procedure was performed according to CLSI-M38-3rd. Biofilm morphology changes revealed with scanning electron microscopy (SEM). Results: Twelve F. solani strains displayed the capacity to form biofilms from patients wearing contact lenses, while 8 A. flavus strains were recovered from cornea scrapings of trauma. Itraconazole, posaconazole and natamycin had the maximum activity against biofilms of all tested filamentous strains (MIC ranging from 0.031 - 0.25 µg/mL, 0.031 - 0.25 µg/mL and 2 - 4 µg/mL), respectively. Three F. solani and one A. flavus strains showed the high MIC values against voriconazole (MIC ≥ 1 µg/mL). Posaconazole revealed the lowest MIC values against biofilms of two strains (MIC ranging from 0.031 - 0.25 µg/mL); however, no significant difference was observed for itraconazole (P > 0.05). The efficacy of 16 µg/mL and 4 µg/mL of voriconazole was confirmed for biofilm of F. solani and A. flavus, respectively. The considerable changes in the morphologies of improved biofilms were seen by SEM. Conclusions: For the successful treatment of fungal biofilm infections, it was necessary to have knowledge of the mechanism of action, penetration rates, and therapeutic concentrations of drugs.