Abstract
Purpose: :
To assess the efficacy of marketed contact lens care products against Fusarium biofilms formed on worn contact lenses using an established in-vitro soft contact lens-Fusarium biofilm model.
Methods: :
Two Fusarium strains (Fusarium solani 6914 and Fusarium oxysporum 8996) from two patients with fungal keratitis were incubated with three different types (lotrafilcon A, etafilcon A, and balafilcon A) of worn contact lenses from three different subjects under conditions that facilitate biofilm formation. Biofilm was quantified using a tetrazolium XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl) -2H -tetrazolium -5 -carboxanilide] assay. Susceptibilities of the biofilm growth phases of the fungi to five common multipurpose (MPS) contact lens care solutions (three polymeric biguanide-preserved and two polyquaternium-preserved) and two hydrogen peroxide care systems were assessed. Effective antifungal activity was defined if the care product achieved >=50% reduction in the metabolic activity of treated biofilms, compared to phosphate-buffered saline-soaked, worn controls.
Results: :
Both Fusarium solani and Fusarium oxysporum strains formed biofilms on worn lotrafilcon A, etafilcon A, and balafilcon A contact lenses. The biofilms of F. solani on all three lens types were consistently susceptible to both hydrogen peroxide care systems (growth reduction of 84-97%, p<=0.01) and two of the five MPS (growth reduction of 62-85% for a biguanide-preserved MPS, p<=0.01; growth reduction of 92-96% for a polyquaternium-preserved MPS, p<0.01). The biofilms of F. oxysporum on all three lens types were consistently susceptible to both hydrogen peroxide care systems (growth reduction of 79-99%, p<=0.005) and one of the five MPS (growth reduction of 93-96% for a polyquaternium-preserved MPS, p<=0.004).
Conclusions: :
F. solani and F. oxysporum form biofilms on all three types of worn contact lenses, which are resistant to the antifungal activity of several soft contact lens care products. Only the hydrogen peroxide care systems and one polyquaternium-preserved MPS consistently demonstrated effective antifungal activity against both Fusarium strains on all three lens types.
Keywords: contact lens • fungal disease