The immune response of the host: an aid to etiology, pathogenesis, diagnosis, and epidemiology of bacterial infections.

The antibody response of patients with various infections has been utilized as an aid to diagnosis since the early days of scientific microbiology, as exemplified by the Widal, Wassermann, and Weil-Felix tests. A variety of serologic techniques have been used to this end. In our laboratories we have studied the antibody response by means of the passive bacterial hemagglutination test on patients with a variety of bacterial infections, including enteropathogenic E. coli enteritis, salmonellosis, shigellosis, urinary tract infection, and Pseudomnonas aeruginosa infection. This method is based on the fact that various bacterial antigens, polysaccharide in nature, readily become attached to the surface of erythrocytes, resulting in the acquisition of a new serologic specificity. These antigen-modified red blood cells are agglutinated in the presence of homologous bacterial antibodies. It is the purpose of this paper to illustrate the potential usefulness of such studies as an aid to etiology, pathogenesis, diagnosis, and epidemiology.