[Passive hemagglutination test with capsular and somatic antigens of Pasteurella multocida strains isolated from...

Comparative investigations were carried out with the passive hemagglutination reaction in the serotyping of 14 reference and 34 P. multocida strains isolated from birds with three types of antigens obtained from one and the same bacterial mass: capsular extracts obtained by Carter's method (1), thermostable capsular extracts obtained after Carter and additionally heated at 100 C degrees for one hour (2), thermostable somatic extracts obtained after the additional heading of the depot of bacterial mass, treated after Carter at 100 C degrees for one hour (3). The results obtained with the three extracts correlated fully with each other as established with the passive hemagglutination test. Out of 34 strains 76.47 per cent were typed with the use of two of the capsular extracts, and 97.05 per cent--with the thermostable somatic extracts. Thermostable somatic extracts obtained from reference and field strains of P. multocida showed type specificity according to the classification of Carter. Of the P. multocida strains isolated from birds that succumbed to acute or chronic form of fowl cholera 97.06 per cent were typed as serotype A, and 2.94 per cent--chiefly in the chronic form of the disease--as serotype B. It was found that immunodiffusion conducted with capsular extracts was the most suitable method for the detection of antibodies in the sera of rabbits against P. multocida prior to the animals' hyperimmunization with type cultures.