Immunological studies of an antigen common to many gram-negative bacteria with special reference to E. coli. Characterization and biological significance.

A number of different bacterial strains were analyzed for the presence of common antigens using immunodiffusion techniques. Most of the studied E. coli strains had many common antigens. Especially one antigen was found in all investigated E. coli as well as Proteus and Pseudomonas strains and antibodies to this antigen were also recognized in antimeningococcal antiserum. The antigen was found possibly to be at least partly a protein with low carbohydrate content located in the inner part of the cell wall and specific antiserum to it was produced by immunizing rabbits. Antiserum to the common antigen did not protect against intraperitoneal infection in mice, or against hematogenous pyelonephritis in rabbits. Irregularly in a few patients with pyelonephritis, a very low antibody response was indicated using indirect hemagglutination technique. A possible significance of the antigen for the future quantitation of antibodies to gram-negative bacteria is discussed, as well as of the specific antiserum for the diagnosis of gram-negative bacterial strains using immunodiffusion techniques.