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Updated: Aug 17, 2026
The Synergistic Effect of Visible Light and Gentamycin on Pseudomona aeruginosa Microorganisms
Published on: July 2, 2013
Continuous flow perfusion of gentamicin with a scleral shell reduces bacterial colony counts in experimental
1Department of Ophthalmology, University of Toronto, Ontario, Canada.
Abstract:
We have previously shown the pharmacokinetic value of delivering gentamicin to the rabbit anterior segment using the Morgan Therapeutic Lens. The present study utilized an intrastromal injection model of Pseudomonas keratitis to test the therapeutic efficacy of continuous flow delivery of gentamicin with the Morgan therapeutic lens. All eyes (n = 52) received an intrastromal injection of approximately 1800 colony forming units (CFU) of Pseudomonas aeruginosa. At 22 hours after injection, eyes were perfused for 6 hours with saline or gentamicin (1, 2.5 or 5 mg/ml), or received gentamicin drops (13.6 mg/ml) at 15 minutes for four doses, then hourly for 6 hours. Corneas were homogenized and plated to determine bacterial survival, and expressed as log colonies (CFU). Log CFU recovered were 7.37 +/- 0.04, 6.64 +/- 0.20, 5.64 +/- 0.31, and 3.56 +/- 0.50 log CFU for saline perfusion, 1, 2.5, 5 mg/ml gentamicin perfusion respectively. Following six hours of treatment with topical fortified gentamicin drops, 5.93 +/- 0.34 log CFU were recovered. Gentamicin perfusion (5 mg/ml) was significantly different from saline or the other treatment groups (P < 0.05). Continuous corneal perfusion with the Morgan Therapeutic Lens demonstrated an increasing dose response curve with increasing perfusate concentration. It was effective in the treatment of experimental Pseudomonas keratitis.
Insights
Continuous delivery of gentamicin using the Morgan Therapeutic Lens effectively treated Pseudomonas keratitis in rabbits. This method showed a significant dose-dependent reduction in bacterial load compared to saline or topical drops.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Pharmacology
Background:
- Pseudomonas keratitis is a serious eye infection.
- Previous studies indicated the pharmacokinetic benefits of the Morgan Therapeutic Lens for anterior segment drug delivery.
- An effective therapeutic strategy for Pseudomonas keratitis is needed.
Purpose of the Study:
- To evaluate the therapeutic efficacy of continuous gentamicin perfusion via the Morgan Therapeutic Lens in a rabbit model of Pseudomonas keratitis.
- To compare this delivery method against topical gentamicin drops and saline control.
Main Methods:
- Rabbits (n=52) were inoculated with Pseudomonas aeruginosa intrastromally.
- Eyes were treated with saline, or gentamicin (1, 2.5, 5 mg/ml) via continuous perfusion using the Morgan Therapeutic Lens for 6 hours.
- A control group received topical gentamicin drops.
- Bacterial survival was quantified as log colony-forming units (log CFU).
Main Results:
- Continuous gentamicin perfusion significantly reduced bacterial load compared to saline (P < 0.05).
- A dose-dependent efficacy was observed, with 5 mg/ml gentamicin perfusion yielding the lowest log CFU (3.56 +/- 0.50).
- Topical gentamicin drops resulted in 5.93 +/- 0.34 log CFU, which was less effective than high-concentration perfusion.
Conclusions:
- Continuous corneal perfusion with gentamicin using the Morgan Therapeutic Lens is an effective treatment for experimental Pseudomonas keratitis.
- This method demonstrates a clear dose-response relationship and superior efficacy compared to conventional topical drops at the tested concentrations.
