Abstract
Purpose: :
Fibrin is a key component of biofilms acting as a conditioning layer or matrix during biofilm development. Activated Protein C (APC) is a potent physiologic anticoagulant with profibrinolytic properties. This study assessed the activity of APC against soft contact lens associated fungal biofilms using an in-vitro established soft contact lens fungal biofilm model.
Methods: :
Fusarium solani 6914 and Fusarium oxysporum 8996 were incubated with three different types of worn contact lenses (lotrafilcon A, balafilcon A, and etafilcon A) from three different subjects under conditions that facilitate biofilm formation. Both strains were obtained from patients with fungal keratitis. Biofilm was quantified using a tetrazolium XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl) -2H -tetrazolium -5 -carboxanilide] assay. Susceptibilities of the fungal biofilm growth phases to 25 ug/ml of APC solution were assessed under two separate conditions: when the APC solution was added during the adhesion phase of biofilm development or after 48 hours of mature biofilm formation.
Results: :
APC was not effective against F. solani biofilm formation when added during the adhesion phase. However, when added after mature biofilm had been formed, APC significantly reduced F. solani biofilm activity by 69%, 72%, and 81% for etafilcon A, lotrafilcon A, and balafilcon A lenses, respectively, compared to phosphate buffered saline-soaked worn-lens controls (p<0.05). F. oxysporum biofilm activity was reduced by 26%, 1%, and 1% on etafilcon A, lotrafilcon A, and balafilcon A lenses, respectively, compared to phosphate buffered saline-soaked worn-lens controls.
Conclusions: :
APC has potent antifungal activity against a F. solani soft contact associated biofilm using an XTT-based metabolic activity assay. There is variability in its effect as it was ineffective against F. oxysporum or when added prior to mature biofilm development. Nevertheless, further study is warranted as APC is an agent that may have novel anti-biofilm activity and it has potential to be used in combination with contact lens disinfecting products to reduce contact lens associated biofilms.
Keywords: contact lens • fungal disease