A murine model of contact lens-associated fusarium keratitis.

PURPOSE: Fusarium solani and F. oxysporum were the causative organisms of the 2005/2006 outbreak of contact lens-associated fungal keratitis in the United States. The present study was an investigation of the ability of F. oxysporum grown as a biofilm on silicone hydrogel contact lenses to induce keratitis.

METHODS: A clinical isolate of F. oxysporum was grown as a biofilm on lotrafilcon A contact lenses, and a 2-mm diameter punch was placed on the abraded corneal epithelium of either untreated or cyclophosphamide-treated C57BL/6 mice or of IL-1R1(-/-), MyD88(-/-), TLR2(-/-), or TLR4(-/-) mice. After 2 hours, the lens was removed, and corneal opacification, colony forming units (CFUs), and histopathology were evaluated.

RESULTS: C57BL/6 mice developed severe corneal opacification within 24 hours and resolved after four days. In contrast, corneal opacification progressed in cyclophosphamide-treated mice, and was associated with unimpaired fungal growth in the cornea, and with hyphae penetrating into the anterior chamber. The phenotype of MyD88(-/-) and IL-1R(-/-) mice was similar to that of cyclophosphamide-treated animals, with significantly impaired cellular infiltration and fungal clearance. Although TLR4(-/-) mice developed a cellular infiltrate and corneal opacification similar to C57BL/6 mice, the CFU count was significantly and consistently higher.

CONCLUSIONS: Fusarium grown as a biofilm on silicone hydrogel contact lenses can induce keratitis on injured corneas, with disease severity and fungal killing dependent on the innate immune response, including IL-1R1, MyD88, and TLR4.