July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Different Concentrations of Topical Fortified Vancomycin Produce Differences in Antibacterial Efficacy in an Experimental Model of MRSA Keratitis
Author Affiliations & Notes
  • Eric G Romanowski
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • John Romanowski
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Kathleen A Yates
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Alex Mammen
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Deepinder K Dhaliwal
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Vishal Jhanji
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Regis P Kowalski
    The Charles T. Campbell Laboratory, UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Eric Romanowski, None; John Romanowski, None; Kathleen Yates, None; Alex Mammen, None; Deepinder Dhaliwal, None; Vishal Jhanji, None; Regis Kowalski, None
  • Footnotes
    Support  The Charles T. Campbell Ophthalmic Microbiology Laboratory, NIH Core Grant EY08098, RPB, Eye & Ear Foundation
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 835. doi:https://doi.org/
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    • Get Citation

      Eric G Romanowski, John Romanowski, Kathleen A Yates, Alex Mammen, Deepinder K Dhaliwal, Vishal Jhanji, Regis P Kowalski; Different Concentrations of Topical Fortified Vancomycin Produce Differences in Antibacterial Efficacy in an Experimental Model of MRSA Keratitis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):835. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Fortified 50 mg/ml vancomycin (VAN) is used clinically for the topical treatment of MRSA keratitis, but patient comfort has many clinicians using concentrations of 25 mg/ml or lower. The goal of this rabbit study was to compare the antibacterial efficacy of different concentrations of fortified VAN for the treatment of experimental methicillin-resistant Staphylococcus aureus (MRSA) keratitis.

Methods : Both corneas of 45 rabbits were intrastromally inoculated with ~2000 CFU (colony forming units) of MRSA strain K950. The corneal epithelium was removed in the left eyes to mimic corneal ulceration (abraded), while the epithelium remained intact in the right eyes (intact). After 4 hours, 9 rabbits were euthanized to determine the corneal CFU of MRSA at the onset of treatment. The remaining rabbits were divided into 4 treatment groups (n=9): 1) 50 mg/ml VAN, 2) 25 mg/ml VAN, 3) 12.5 mg/ml VAN, and 4) saline. The rabbits were treated topically in both eyes every 15 minutes for 5 hours. One hour after treatment, the rabbits were euthanized, the corneas were removed, homogenized, and standard colony counts were determined to statistically analyze VAN penetration, treatment efficacy, and bactericidal effect (3-log10 decrease in CFU).

Results : For abraded corneas, the CFU from 50 mg/ml VAN treatment were significantly lower than 25 mg/ml and 12.5 mg/ml (P≤0.05 Kruskal-Wallis). All VAN groups produced fewer CFU than saline (P≤0.05). The CFU of 25 mg/ml VAN were lower, but statistically similar to 12.5 mg/ml VAN. The 50 mg/ml VAN 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 (P≤0.05).

Conclusions : Our rabbit study indicates that topical fortified 50 mg/ml VAN is the most potent concentration for the treatment of MRSA keratitis. The clinician may need to reassess the topical vancomycin concentration used with regards to antibacterial efficacy and patient comfort for the treatment of MRSA corneal infections.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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