Iontophoresis of tobramycin for the treatment of experimental Pseudomonas keratitis in the rabbit.

Iontophoresis of tobramycin sulfate was employed to treat bacterial keratitis induced in rabbits by an intrastromal injection of Pseudomonas aeruginosa. Quantitation of bacterial killing was achieved by culturing corneal homogenates and counting viable bacteria per cornea after treatment. When the rabbits received two iontophoretic treatments, iontophoresis significantly reduced the number of bacterial colony-forming units, compared with the use of an eyecup without current or two subconjunctival injections of 20 mg of tobramycin sulfate, and with untreated controls. The results of iontophoresis were not significantly different from those involving treatment with topical fortified drops (40 mg/mL). A single iontophoresis treatment was compared with the use of an eyecup without current or less fortified topical drops (13.6 mg/mL), as well as with untreated controls. Iontophoresis was significantly better than either the eyecup or the topical fortified tobramycin drops in reducing viable bacteria in the corneas. Iontophoresis may be a useful adjunct in the treatment of severe corneal bacterial infections.