Endophthalmitis: Development of a more effective and cost saving bacterial killing therapy

Abstract

Purpose : Endophthalmitis is an infection of the eye that can rapidly result in substantial loss of vision, and may require removal of the eye. Interest in this complication has increased recently over concerns that infection rates of endophthalmitis are rising. It is estimated that in the USA, there are about 3 Million Cataract surgeries per year with over 10 million worldwide. Moreover, the frequency of invasive procedures associated with endophthalmitis has risen greatly with the recent advent of intracameral injections as the standard of care for macular degeneration and other retinovascular indications. The purpose of this study is to investigate combinations of cefuroxime, cefazolin and/or tobramycin as possible replacements for fluoroquinolones (moxifloxacin) for reducing the incidence of endophthalmitis.

Methods : Initially, we examined individual antimicrobials to determine the minimal bactericidal concentrations (MBC) of each individual treatment, against Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, two clinical isolates of MRSA, and Staphylococcus epidermidis, by both the Disk Diffusion and the Colony Forming Unit (CFU) assays. We then used this data in a combinatorial study.

Results : The results allowed us to examine whether the combination antimicrobials were additive, synergistic or antagonistic compared to the results of the individual antimicrobial treatments. We found combinations that were synergistic against all the bacteria tested, resulting in total killing of all bacteria.

Conclusions : We found some combinations of these antimicrobials that were synergistic in total killing of all bacteria tested, at concentrations of all three antimicrobials, which were lower than those from individual MBC results. In addition these combinations were more effective in bacterial killing than the currently used fluoroquinolones.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.