Keratitis caused by Pseudomonas aeruginosa: treatment in the experiment

Abstract

The aim of the study was to investigate the effectiveness of treatment of keratitis caused by Pseudomonas aeruginosa using official ophthalmic forms of antibiotics, which are effective against the pathogen. Materials and methods. Adult 36 rabbits weighing 3–3.5 kg were undergone the causing of purulent keratitis by applying a clinical strain of P. aeruginosa as a suspension of one-day culture of the microorganism at a concentration of 5×108 CFU/ml on the partially de-epithelialized (approximately 1 cm2) cornea followed by coating for 24 hours with soft contact lens made of belafilcon A (water content: 36 %, oxygen permeability DK/t:110.0). In half of the cases, microbial biofilms were pre-grown on the contact lens surfaces via incubation into the broth culture of P. aeruginosa strain. The treatment of keratitis was performed with ocular official forms of antibiotics: levofloxacin 0.5 % (5 mg/ml), ciprofloxacin 0.3 % (3 mg/ml), tobramycin 0.3 % (3 mg/ml). Their effectiveness against the strain of P. aeruginosa was previously proven in vitro. The animals were divided into three corresponding as for severity of keratitis groups, in each of which treatment was performed with one of the three above antibiotics. In half of the cases within each group, the antibiotic was combined with the ocular official form of decamethoxine 0.02 % (0.2 mg/ml). The antibiotics were used in the mode of the most frequent instillation for the first 2 days after the onset of purulent keratitis, then 5 and 4 times a day. The assessment included evaluation of clinical signs, culturing, ophthalmological examination of the cornea with fluorescein test and photofixation. Animals were removed from the study on days 7th, 10th, 14th (depending on the term of epithelialization of the affected cornea). Results. Totally, 36 cases of purulent keratitis caused by P. aeruginosa in rabbits were modelled: 8 moderate (22.2 %), 13 semi-severe (36.6 %), 15 – severe (41.7 %).