Susceptibility of aged mice to Staphylococcus aureus keratitis

PURPOSE: To determine the effect of age on the extent of pathogenesis of Staphylococcus keratitis in the mouse. METHODS: Corneas of young and aged mice (BALB/c, A/J, and C57BL/6) were scarified and topically inoculated with S. aureus. Slit lamp examination (SLE) and histopathology were performed, and bacterial colony forming units and myeloperoxidase activity were determined. RESULTS: SLE scores of infected eyes of aged mice were significantly higher at days 1 and 3 postinfection (PI) as compared to infected young mice. Histopathological changes observed in all aged mice were more severe than those in young mice. Young BALB/c and A/J mice demonstrated minimal signs of keratitis by day 3 PI, whereas aged mice of both strains demonstrated severe keratitis by day 3. Young C57BL/6 mice showed no clinical signs of keratitis, whereas aged C57BL/6 mice demonstrated moderate keratitis. CONCLUSIONS: Aged mice with S. aureus keratitis demonstrated increased pathology as compared to young mice.