Egg contamination by Salmonella serovar enteritidis following vaccination with Delta-aroA Salmonella serovar typhimurium

The efficacy of an aroA Solmonella serovar tyhphimurium modified live vacci ne to decrease internal egg contamination after oral challenge of hens with egg-contaminating Salmonella serovar enteritidis was assessed. Challenge w as with a mixed phenotype of S. enteritidis that had virulence characterist ics previously associated with enhanced oral invasiveness and egg contamina tion in chickens. Immunized birds had fewer positive ovary/oviduct pools an d lower cfu g(-1) cecal contents than did non-immunized birds, but the diff erences were not significant. The number of positive intestinal (duodenum, jejunum, ileum) and organ (spleen, kidney, liver) pools following challenge from each treatment group were equivalent. Most importantly. immunization did not decrease egg contamination. These results suggest that the ability of modified live vaccines to reduce internal egg contamination by S. serova r enteritidis can be assessed using characterized strains for challenge. (C ) 2001 Federation of European Microbiological Societies. Published by Elsev ier Science B.V. All rights reserved.