Synergistic effect of immune gamma-globulin fraction on protection by antibiotic against corneal ulcers in experimental mice infected with Pseudomonas aeruginosa.

Synergistic effects of immune gamma-globulin fraction containing antibodies of OPE, protease and elastase of Pseudomonas aeruginosa on the activities of antibiotic, dibekacin (DKB), in the cornea of mice were examined for the purpose of studying therapy for corneal ulcers due to Pseudomonal infection. In the case of the intramuscular injection, a medium effective dose (ED50) of DKB alone against corneal ulcers caused by strain IID 1210 of P. aeruginosa in experimental mice was 620 mug per mouse. When 15.6 to 18.7 mg of gamma-globulin fraction was subcutaneously given to each mouse prior to the infection with strain IID 1210, opacity instead of severe ulcers was observed only in the central area of cornea. The immune gamma-globulin fraction was far more effective in the protection of cornea from the infection than the calf serum that showed no antibody titer against OEP, protease and elastase. The ED50 values of DKB's combined with the immune gamma-globulin, Fr. 1 and Fr. 2, and the calf serum were 34 and 73, and 480 mug per mouse respectively. There was found no statistical difference in ED50 value between DKB combined with the calf serum and one without it. There was, however, significant difference in ED50 value between DKB's combined with Fr. 1 and Fr. 2, and one with the calf serum. When DKB alone is dropped in the eye of mouse for the protection, the ED50 value was 15 mug per mouse. When 1.56 to 1.87 mg of the immune gamma-globulin fraction was dropped in the eye after the infection with P. aeruginosa, there was observed no protection against corneal ulcers. the ED50 values of DKB's combined with Fr. 1, Fr. 2 and the calf serum were 0.96, 0.94 and 13 mug per mouse, respectively. There was no significant difference between the ED50 values of 0.96 and 0.94 mug, and between 15 and 18 mug. There was, however, significant difference between the former ED50 values (0.96 and 0.94 mug) and the latter ones (15 and 18 mug). The combination of DKB and the immune gamma-globulin fraction was found to be superior to the combination of DKB and the calf serum in the therapeutic effect on corneal ulcers caused by strain IID 1210 of P. aeruginosa.