PASTEURELLA-MULTOCIDA INFECTION IN THE CHICKEN-EMBRYO

Pasteurella multocida infection in embryonated chicken eggs was studie d by chorio-allantoic membrane inoculation. Strain differences were de monstrated in terms of lesion severity and time to death, especially d uring the first 24 h post-inoculation. A strain of low virulence gave a clear dose response but more virulent strains did not. Comparable re sults were obtained by infecting 6-week-old chickens. The main lesions in inoculated embryos appeared as severe vascular involvement of the entire embryo and feather tracts, thickening of the chorio-allantoic m embrane, and enlargement and congestion of the yolk sac. The bacteria were demonstrated by transmission electron microscopy, either extracel lularly or multiplying intracellularly in hepatocytes, heart tissue, a nd in the hyperplastic layer of the chorio-allantoic membrane, with re sulting damage to the cellular organelles, and severe tissue changes. (C) 1998 W.B. Saunders Company Limited.