Study of efficacy of intravitreal injection of ciprofloxacin versus vancomycin and ceftazidime in treating experimental endophthalmitis

ABSTRACT

Endophthalmitis is a severe inflammation of the interior of the eye caused by the introduction of contaminating microorganisms. The aim of this study was to compare the efficacy of intravitreal injection of vancomycin and ceftazidime versus ciprofloxacin in an experimental model of Staph. Epidermidis induced endophthalmitis in rabbits. The study was conducted on the right eyes of 35 pigmented rabbits, 5 of which were used as control group. All remaining 30 eyes were inoculated with 3 x 10[6] CFU / 0.1 ml of Staph. epidermidis then, they were divided into 3 equal groups. 24 hours postinoculation, group I was given no treatment, group II received a combined intravitreal injection of vancomycin [1 mg /0.1 ml] and ceftazidime [2.25 mg / 0.1 ml], and group III received an intravitreal injection of ciprofloxacin [100 micro g/ 0.1 ml]. From each group, 72 hours postinoculation, 5 rabbits were used for clinical examination and then they were sacrificed, their right eyes were enucleated, and vitreous colony count was done. The other 5 rabbits were also sacrificed, their right eyes were enucleated, and histologlcal examination by LM and TEM was performed. The clinical examination revealed that the conjunctival injection and the corneal oedema were significantly less in group II in comparison to group I and III. The bacterial colony count was markedly decreased in group II in comparison to group I and III with a significant difference. Histological examination by LM and TEM revealed that the endophthalmitis group [group I] showed complete loss of architecture of the retina and choroid with disruption of the Bruch's membrane. Multiple degenerated cells and red blood cells were seen infiltrating the degenerated retina. On the contrary, the retinal structure was preserved to a great extent in group II, [vancomycin and ceftazidime group] except for focal areas of disorganization in the photoreceptor layer and mild invasion by inflammatory cells. Eyes treated with ciprofloxacin showed degeneration of the pigmented epithelial cells and the photoreceptor cell layers, pyknosis and karyolysis of the outer nuclear layer and infiltration of the all retinal layers with mononuclear cellular infiltration. Intravitreal injection of vancomycin [1 mg / 0.1 ml] and ceftazidime [2.25 mg / 0.1 ml] was more effective than ciprofloxacin [100 micro g / 0.1 ml] in improving the clinical signs, decreasing the bacterial colony count, and preserving the retinal structure in Staph. epidermidis endophthalmitis