Abstract
Purpose :
Bacterial endophthalmitis can lead to significant vision loss even after prompt and proper treatment, partially due to the limited time of antibiotics’ residence in the vitreous cavity. The purpose of this study was to evaluate the efficacy of a novel drug formulation, which is specifically designed for sustained intraocular release of moxifloxacin, in an experimental model of Escherichia coli (E. coli) – induced endophthalmitis.
Methods :
Experimental endophthalmitis was induced in both male and female Sprague-Dawley rats. Animals received an intravitreal injection of approximately 10.000 colony – forming units (CFUs)/eye of the E. coli strain U13, which is susceptible to moxifloxacin. Six hours later, animals received a second intravitreal injection with either free or liposomal moxifloxacin (conventional vs. sustained release delivery respectively). A recently developed novel liposomal formulation of moxifloxacin was used. Clinical scores were evaluated in vivo with slit lamp biomicroscopy and direct ophthalmoscopy and animals were euthanized at 30 hours post treatment, eyes were enucleated and bacterial growth rate was assessed.
Results :
An inoculum of 10.000 CFUs/eye of E. coli U13 resulted in conjunctival hyperemia, purulent exudations, iritis and miosed pupils (posterior synechiae) at 30 hours with mild to moderate inflammatory scores and an average bacterial load of 105 CFUs/eye. An intravitreal injection of liposomal moxifloxacin (1,6 μg/μl) 6 hours after the bacterial inoculation, resulted in significant reduction of the bacterial load at 30 hours to an average of 200 CFUs/eye.
Conclusions :
Escherichia coli – induced endophthalmitis can be achieved in rats and is a highly reproducible model of experimental gram-negative bacterial endophthalmitis. Low inocula of E. coli strain U13 result in mild to moderate progress of the inflammatory signs, thus allowing pharmaceutical intervention. Liposomal moxifloxacin seems as effective as the free antibiotic at early time points. Further experimentation is currently ongoing in order to evaluate the efficacy of the novel moxifloxacin over a longer time frame.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.