Intrastromal Administration of Vancomycin to Maximize Its Early Effect on Methicillin-resistant Staphylococcus Aureus Keratitis: A Rabbit Study

Purpose: To evaluate the early efficacy of intrastromal injection of vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA). Methods: Twenty-four eyes of 24 New-Zealand White rabbits were included in the study. MRSA keratitis was induced in the right eye of each rabbit. On the 24(th) hour after the inoculation of MRSA, eight rabbits received topical vancomycin therapy, eight rabbits received intrastromal vancomycin therapy, and eight rabbits received balanced salt solution and served as the control group. Results: The pre-post differences in epithelial erosion score and total clinical score were higher in the topical vancomycin group than in the intrastromal vancomycin group (p = .033 and 0.016, respectively). The eyes treated topically had higher bacterial load compared with those treated intrastromally (6.97 +/- 0.82 vs. 6.14 +/- 0.63 log10 CFU/g, p = .039). Conclusion: A single dose of intrastromal vancomycin is more effective than the standard loading dose of topical vancomycin in reducing bacterial load.