Posters

Is 2.5% (25mg/ml) vancomycin the same as 5% (50 mg/ml) in the treatment of MRSA keratitis?

Poster Details

First Author: R.Kowalski USA

Co Author(s): E. Romanowski   J. Romanowski   K. Yates   A. Mammen   D. Dhaliwal   V. Jhanji     

Abstract Details

Purpose:

Topical 5% (50 mg/ml) vancomycin is used for the treatment of MRSA keratitis, but patient comfort has many clinicians using 2.5% (25 mg/ml). This rabbit study compares different concentrations of vancomycin in the treatment of experimental MRSA keratitis.

Setting:

Animal Study - University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Methods:

The corneas of both eyes of 45 rabbits were infected with 2000 CFU of MRSA. The corneal epithelium was abraded in the left eyes to mimic corneal ulceration. After 4 hours, 9 rabbits were euthanized to determine the CFU of MRSA at the onset of treatment. 36 rabbits were divided into 4 treatment groups (n=9): 1) 5% vancomycin, 2) 2.5% vancomycin, 3) 1.25% (12.5 mg/ml) vancomycin, and 4) saline. Treatment commenced topically every 15 minutes for 5 hours. After one hour, the corneas were removed, and standard colony counts were determined to analyze vancomycin penetration, treatment efficacy, and bactericidal effect.

Results:

For abraded corneas, the CFU of the 5% vancomycin group were statistically lower than 2.5% and 1.25%, and all vancomycin groups were lower than saline. The CFU of 2.5% were lower but statistically similar to 1.25%. The 5% vancomycin group demonstrated a bactericidal effect and the best penetration. The CFU of the abraded corneas treated with saline were statistically lower than the intact corneas indicating a possible antibacterial effect from the ocular surface.

Conclusions:

Our rabbit study indicates that 5% vancomycin is the most potent concentration for the treatment of MRSA keratitis. The clinician may need to reassess treatment with regards to antibacterial efficacy and patient comfort.

Financial Disclosure:

None