Coagglutination test for identification of Pasteurella multocida associated with hemorrhagic septicemia

Two serogroups (B and E) of Pasteurella multocida associated with hemorrhagic septicemia in cattle were differentiated by a coagglutination test with antibody-coated staphylococci. The group antigen was soluble and heat stable. It was not detectable in unencapsulated cells or their heated extracts. Adsorbed onto human type O erythrocytes, it could be demonstrated by an indirect hemagglutination test with specific antiserum or by coagglutination with specific antibody-coated staphylococci. Antibody-coated staphylococci could detect the soluble group antigen in the plasma and liver extract of mice experimentally infected with P. multocida. The group antigen did not affix to mouse erythrocytes in vivo.