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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #428588
Research Project: Physiological, Microbiological, and Nutritional Mechanisms to Maintain Animal Productivity in the Absence of Antibiotics

Location: Agroecosystems Management Research

Title: Chicken vaccination reduces colonization and dissemination of Salmonella serovar Enteritidis with decreased susceptibility to ciprofloxacin

Author
item Bearson, Bradley
item WHELAN, SAMUEL - Oak Ridge Institute For Science And Education (ORISE)
item ENCINOSA, MAYA - Oak Ridge Institute For Science And Education (ORISE)
item NEUPANE, DURGA - Oak Ridge Institute For Science And Education (ORISE)
item BRADSHAW, DAVID - Oak Ridge Institute For Science And Education (ORISE)
item Monson, Melissa
item Anderson, Christopher
item Bearson, Shawn

Submitted to: NPJ Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2026
Publication Date: 3/9/2026
Citation: Bearson, B.L., Whelan, S.J., Encinosa, M.P., Neupane, D.P., Bradshaw, D.J., Monson, M.S., Anderson, C.L., Bearson, S.M. 2026. Chicken vaccination reduces colonization and dissemination of Salmonella serovar Enteritidis with decreased susceptibility to ciprofloxacin. NPJ Vaccines. https://doi.org/10.1038/s41541-026-01414-y.
DOI: https://doi.org/10.1038/s41541-026-01414-y

Interpretive Summary: Salmonella is one of the leading causes of human foodborne illness. Recently, surveillance systems identified the emergence of chicken and human isolates of Salmonella Enteritidis (a type of Salmonella bacteria) with decreased susceptibility to ciprofloxacin (DSC), a critical antibiotic prescribed for complicated human infections. To address the request by poultry producers and public health agencies for methods to reduce or eliminate DSC Enteritidis in chickens, a live Salmonella vaccine (BBS 1134) was tested for its ability to reduce DSC Enteritidis in broiler chickens. Vaccination of newly hatched chicks prior to exposure to DSC Enteritidis reduced the number of birds colonized with DSC Enteritidis in the gut and spleen by 40% and 72%, respectively, compared to chickens that had not been vaccinated. Enteritidis spread to the bone marrow in 38% of the non-vaccinated chickens at 7 days after inoculation, but vaccination prevented Salmonella migration to the bone marrow. Bone marrow may be a source of chicken product contamination during mechanical separation of meat from the bone. The results also indicated that BBS 1134 vaccination would not interfere with flock monitoring for Salmonella Enteritidis on the farm (differentiation of infected from vaccinated animals (DIVA)). The data indicate that the BBS 1134 Salmonella DIVA vaccine cross-protected chickens against intestinal and systemic colonization with DSC Enteritidis. These results demonstrate the utility of the BBS 1134 vaccine as an intervention strategy to reduce Salmonella in chickens for prevention of contaminated chicken products, which is needed by the U.S. poultry farmers and public health agencies to improve food safety.

Technical Abstract: Salmonella enterica serovar Enteritidis (S. Enteritidis) is one of most common Salmonella serovars associated with human illness in the U.S. and worldwide. Surveillance from the U.S. National Antimicrobial Resistance Monitoring System indicates an increase in both chicken and human isolates of S. Enteritidis with decreased susceptibility to ciprofloxacin (DSC), a critical antibiotic prescribed for complicated human salmonellosis infections. S. Enteritidis reduction in chickens is a priority of poultry producers and public health agencies to improve food safety. In the current study, efficacy assessment of a live Salmonella vaccine (BBS 1134) revealed significant reduction of cecal and splenic colonization, and prevention of dissemination to the bone marrow by DSC S. Enteritidis in broiler chickens. Microbiome analysis indicated the cecal microbiota of vaccinated chickens is distinct compared to mock-vaccinated birds. The IDEXX SE Ab X2 Test did not detect antibodies to S. Enteritidis in vaccinated chicken serum, thereby permitting differentiation of infected from vaccinated animals (DIVA). Altogether, the Salmonella vaccine is a DIVA vaccine, afforded cross-protection, and significantly reduced intestinal colonization and dissemination to the spleen and bone marrow by DSC S. Enteritidis in chickens, thereby offering a prospective intervention for animal production to reduce food product contamination and improve food safety.