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

The efficacy of an aroA Solmonella serovar tyhphimurium modified live vaccine to decrease internal egg contamination after oral challenge of hens with egg-contaminating Salmonella serovar enteritidis was assessed. Challenge was with a mixed phenotype of S. enteritidis that had virulence characteristics previously associated with enhanced oral invasiveness and egg contamination in chickens. Immunized birds had fewer positive ovary/oviduct pools and lower cfu g(-1) cecal contents than did non-immunized birds, but the differences 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. serovar enteritidis can be assessed using characterized strains for challenge. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.