[A human monoclonal antibody cocktail for experimental mouse infection with clinically isolated strains of Pseudomonas aeruginosa].

A human IgG monoclonal antibody cocktail against Pseudomonas aeruginosa serotypes A, B, E, G, I, and M (MCA5) was tested for its therapeutic effect on the infected mice with clinically isolated P. aeruginosa strains. More than 80% of the collected strains were found to belong to the above six serotypes. Direct agglutination with MCA5 gave slight reduced rates, but over 70% of the strains were agglutinated with MCA5. Fifty percent lethal doses of the representative strains to mice (LD50) were estimated, and 50% protective doses of MCA5 to the infected mice with 5 LD50 of the strains (ED50) were determined. MCA5 was found not to be protective to all the infected mice with above six serotypes but protective only to the mice infected with the agglutinated strains. Confirmation of the agglutination of the causative organism with MCA5 is required for the treatment by MCA5. ED50 for a clinically isolated strain and the virulent stock strain were determined under the various challenge doses. It was found that ED50 increased in parallel with the increase of challenged doses but did not change depending on the virulence of the infected strains. These results indicated that this cocktail worked as opsonin. Opsogenic anti-O IgG antibody could be most effective to protect the opportunistic infections caused by the bacteria which have not so powerful exotoxins.