SEROLOGICAL TYPES OF PASTEURELLA-MULTOCIDA ISOLATED FROM TURKEYS AND CHICKENS IN CANADA

Outbreaks of fowl cholera continue to plague the Canadian poultry industry despite widespread immunization against the causative agent, P. multocida. Fowl cholera bacterins currently employed by domestic poultry growers contain 3 serological types, namely, serotypes 1, 3 and 4. A total of 84 strains of P. multocida were isolated in Canada from outbreaks of fowl cholera in turkeys and chickens. Serotyping was accomplished using the gel diffusion precipitin test. Based on the gel diffusion precipitation patterns, 27 serotypes containing 1-6 antigenic determinants were recognized. The most prevalent serotype both in turkeys and chickens appeared to be type 3. Significantly, > 20% of P. multocida isolates failed to react with antisera raised against serotypes 1, 3, and 4.