Strain differentiation of Neisseria gonorrhoeae by reverse passive hemagglutination

A reverse passive hemagglutination test that utilizes human erythrocytes coated with antibody to gonococci was developed to distinguish differences among 11 strains of Neisseria gonorrhoeae. Different rabbits were immunized with each strain of gonococcus. Antibody was purified by passing antiserum over an immunoadsorbent column containing homologous cell walls trapped in a cross-linked polyacrylamide gel. Antibody, after absorption with N. meningitidis, was used for coating 11 individual suspensions of erythrocytes, each with antibody to one gonococcal strain. The panel of coated erythrocytes was added to microtiter trays containing dilutions of homologous bacterial lysate and lysates from 10 heterologous strains. Agglutination titers were highest with homologous lysates, although cross-reactions occurred among some heterologous lysates. Lysates of nongonococcal Neisseria species and of other genera did not agglutinate coated erythrocytes. The reverse passive hemagglutination test can be a useful procedure to distinguish differences among strains of N. gonorrhoeae.