Abstract
Purpose: :
To explore the efficacy of riboflavin-Ultraviolet Light A (UVA) combined treatment in the eradication of corneal infection using a New Zealand White rabbit model of experimental gram-positive bacterial keratitis (Staphylococcus aureus).
Methods: :
One thousand colony-forming units (CFU) of S. aureus were intrastromally injected into rabbit cornea. A total of 24 eyes were infected and then divided into 4 groups: (C) Control group, no treatment; (UVA), treatment with UVA exposure for 30 minutes; (UVA+B2) UVA exposure for 30 minutes + riboflavin (B2) 0.1% drops every 2 minutes for 30 minutes, and (UVA+B2’) UVA exposure for 30 minutes + previously photosensitized riboflavin (B2) 0.1% drops every 2 minutes for 30 minutes. The corneal infections were monitored with digital photography for 5 days, and the appearance was compared with a digital software. The rabbits were then sacrificed, and the corneal buttons were harvested and processed appropriately to calculate the number of colony forming units (CFU) per cornea.
Results: :
An immediate response to the treatment was observed at just 24 h after exposure. The median number of CFU of recoverable bacteria for C (n=6), UVA (n=6), UVA+B2 (n=6), and UVA+B2’ was 307.5, 45, 10, and 9.5, respectively. CFU were significantly reduced with all treatments, compared to the control, but UVA+B2 and UVA+B2’ were the most effective treatments, with no statistical difference between them.
Conclusions: :
These results indicate that UVA combined with riboflavin 0.1% drops appears to be an effective therapy for S. aureus keratitis in the rabbit model. These results may be used as a reference for the future potential treatment of bacterial keratitis in human subjects.
Keywords: keratitis • bacterial disease • Staphylococcus