Chitosan Drug Membrane Implanting Into Perichoroidal Space Against Staphylococcus Aureus Endophthalmitis In Rabbits

Objective:To compare the therapeutic effects of chitosan drug membrane with triamcinolone(TA) implanting into perichoroidal space combined with intraocular Vancomycin injection with the intraocular Vancomycin injection and TA as well as intraocular Vancomycin injection alone for endophthalmitis in rabbits.Methods:To select 30 healthy pigment rabbits(offered by Department of experiment,Wuhan General Hospital of Guangzhou Military Command),weight from2.5～3.0kg,including female and male.All the animals were detected by slit lamp and indirect funduscope before surgery.The right eyes of 30 normal rabbits received an intravitreal injection of ATCC 25923 standard strain Staphylococcus aureus organisms 10⁴ colony-forming units(CFU)/0.1mL,0.1mL.Twenty-four hours after inoculation,all rabbits were randomly divided into 3 groups:Group A received an intravitreal Vancomycin;Group B received an intravitreal Vancomycin plus TA;Group C received an intravitreal Vancomycin combined with implanting TA into perichoroidal space.The drug membrane was a kind of the membrane of gelatin-chitosan offered by Center of biology of Wuhan Ligong University. Clinical observation was done every day with slit lamp and indirect ophthalmofundoscope,clinical grading was done on the 3^rd,7^th and 14^th day. Pictures about the anterior segment was taken on 7^th and 14^th day after therapy. Vitreous cultures were obtained on the 5^th day after therapy.B ultrasound test was arranged at 24 hours after inoculation and the 14^th day after therapy. Histopathologic grading and electromicroscope observation was carried out at the 14^th day on retina.Adopting to SPSS 11.0 software analyzed the result.Clinical inflammation grading used Friedman test of K Related Sample Test,positive ratio of bacterium cultureχ² test of R×C data,comparison to the ratio of interblock Bonfferoni test,P＜0.05 was significance difference.Results:All the animals appeared palpebral edema,visible conjunctiva injection,corneal edema and opacity,anterior chamber flash(+),anterior chamber exsudation(+),iris congestion and vitreous empyema.The clinical grading was done on the 3^rd,7^th and 14^th day on the cornea,conjunctiva,iris and vitreous,the inflammation in group C was markedly less than two other groups.The clinical grading result showed on the 3^rd,7^th,14^th day:1) Conjunctiva there existed significant difference among three groups on the 3^rd,7^th and 14^th dayχ²=8.720, 14.788,13.034;P=0.013,0.001,0.001;2) Cornea there existed significant difference among three groups on the 3^rd,7^th and 14^th dayχ²=11.793,7.063, 11.308;P=0.003,0.000,0.004;3) Iris there existed significant difference among three groups on the 3^rd,7^th and 14^th dayχ²=8.897,13.768,9.923;P=0.012,0.001, 0.007;4) Vitreous there existed significant difference among three groups on the 3^rd,7^th and 14^th dayχ²=8.000,7.760,9.923;P=0.018,0.021,0.007.The bacterium detection ratio was no significant difference at the 5^th day after surgeryχ²=0.373, P=0.830.Retinal detach of the C groups occurred less than two other groups via B Scanχ²=8.416,P=0.015.Whole collection showed that cornea of A group and B group were midrange or slight injection,C group was transparent;A group and B group have empyema in vitreous cavity,C group almost have after therapy.The histology structure of A group and B group displayed proliferated kerato-pavement-epithelium,inflammatory cell infiltrate,blood vessel entering the layer of cornea,C group was intact under the light microscope(LM).Iris of A group and B group were injection,proliferated dramatically,inflammatory cell infiltrate,C group not congestion.Retina of A group lost the normal structure,B group intra-or external granular layer disordered and neuroepithelial layer lost,C group was nearly normal.Transmission electron microscope(TEM) detected that the retinal pigment epithelium(RPE) structure of C group was integrity and cellular organs show clearly.Conclusion:Chitosan drug membrane with TA administrated into perichoroida space is safe and effective.It will be a better way to treat bacterial endophthalmitis.