Serotyping of Pasteurella multocida isolants from poultry.

A total of 607 Pasteurella multocida strains were isolated in Israel from turkeys, geese, and chickens. Serotyping was carried out by the gel-diffusion precipitin test. The antigens were heat-stable saline extracts of the organisms, and the diagnostic sera were produced in chickens using formalinized bacterins. Among 31 serotypes containing one to five antigenic factors, serotypes 1 and 3 accounted for 58.1%, 80.8%, and 88.9% isolants from turkeys, geese, and chickens, respectively. On the basis of the incidence of these serotypes in the flocks examined, serotype 1 was predominant. The variety of antigenic components was greatest for strains from turkeys, with some untypable. The record of isolants from various flocks indicated the wide distribution of many of the strains. Attention was drawn to strains with multiple antigenic factors and the possible implication of their presence in the preparation and use of vaccines.