Efficacy of care solutions against contact lens-associated Fusarium biofilms.

PURPOSE: The aim of this study is to assess the effect of lens wear on the formation of soft contact lens-associated Fusarium biofilms and to determine the efficacy of marketed contact lens care products against such biofilms.
METHODS: Using an established in vitro soft contact lens-Fusarium biofilm model, two clinical Fusarium isolates (F. solani B6914 and F. oxysporum B8996) were incubated with three different types (lotrafilcon A, etafilcon A, and balafilcon A) of worn contact lenses under conditions that facilitate biofilm formation. Unworn lenses were used as internal controls for biofilm formation. Biofilm was quantified using a tetrazolium XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) assay. In addition, susceptibilities of the fungal biofilm growth phases to the five most common multipurpose contact lens care solutions available at the time of study (three polymeric biguanide-preserved and two polyquaternium-preserved) and two hydrogen peroxide care solutions were assessed.
RESULTS: Both Fusarium strains formed dense biofilms on each of the contact lens types tested. Worn lenses showed no differences in the ability of biofilm to form compared with unworn lenses except worn etafilcon A lenses which formed more biofilm with F. oxyspourm B8996 compared with unworn controls. Lens material did not influence biofilm formation. The biofilms of F. solani on all three lens types were consistently susceptible to both hydrogen peroxide care systems (growth reduction of 84 to 97%, p ≤ 0.001) and two of the five multipurpose solutions (MPSs) (growth reduction of 62 to 85% for a biguanide-preserved MPS, p ≤ 0.05; growth reduction of 92 to 96% for a polyquaternium-myristamidopropyl dimethylamine preserved MPS, p < 0.001). The biofilms of F. oxysporum on all three lens types were consistently susceptible to both hydrogen peroxide care systems (growth reduction of 79 to 99%, p ≤ 0.001) and one of the five MPSs (growth reduction of 93 to 96% for a polyquaternium-myristamidopropyl dimethylamine preserved MPS, p ≤ 0.001).
CONCLUSIONS: F. solani and F. oxysporum form biofilms on lotrafilcon A, etafilcon A, and balafilcon A 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-myristamidopropyl dimethylamine-preserved solution consistently demonstrated effective antifungal activity against both Fusarium strains on all three lens types.