Tissue colonization and egg and environmental contamination associated with the experimental infection of cage-free laying hens with Salmonella Braenderup.

Authors: Garcia, Javier; Gast, Richard; Guard, Jean; KARCHER, DARRIN - Purdue University; Jones, Deana

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2021
Publication Date: 2/17/2022
Citation: Garcia, J.S., Gast, R.K., Guard, J.Y., Karcher, D.M., Jones, D.R. 2022. Tissue colonization and egg and environmental contamination associated with the experimental infection of cage-free laying hens with Salmonella Braenderup. Avian Diseases. 66:74-78.

Interpretive Summary: n 2018, a major foodborne outbreak associated with shell eggs occurred in the US caused by Salmonella Braenderup. Salmonella Braenderup has been reported in laying hens and the production environment, however little is know about its ability to infect laying hens and contaminate eggs. The objective of this study was to examine the invasiveness of Salmonella Braenderup in laying hens, as well as its ability to persist in the production environment. Specific-pathogen-free laying hens (4 trials; 72 hens/trial) were orally challenged with Salmonella Braenderup. Six days after inoculation, half the hens were euthanized and organ samples were collected. Egg and environmental samples were collected day 7- 20 post-inoculation and day 7-27 post-inoculation to detect Salmonella Braenderup. Recovery on Salmonella Braenderup was highest in ileocecal tissue samples (11.1-33.3 %; P < 0.05), with little to no recovery in other collected tissue samples. In a small number of shell emulsions (0-2.9 %; P < 0.01), Salmonella Braenderup was detected. Salmonella Braenderup was recovered in Trial 1 at a high rate (92.5 %; P < 0.0001) in the substrate composite samples however recovery of Salmonella Braenderup was low in the other egg and environmental samples. These trials indicate that although Salmonella Braenderup can persist in the environment at low levels, it is not an invasive Salmonella serotype for cage-free laying hens, especially when compared to serotypes of concern to the egg industry.

Technical Abstract: In 2018, a national recall of shell eggs in the US occurred due to human illness caused by Salmonella Braenderup. Although previous studies have identified Salmonella Braenderup (SB) in laying hens and the production environment, little is known about the ability of this Salmonella serovar to infect laying hens and contaminate eggs. The objective of this study was to examine the invasiveness of Salmonella Braenderup in laying hens, as well as its ability to persist in the production environment. Specific-pathogen-free laying hens (4 trials; 72 hens/trial) were orally challenged with 107 colony-forming units of SB. On day 6 post-inoculation, half of the challenged hens were euthanized, and samples of ileocecal, liver, spleen, ovary, oviduct tissues were collected and cultured for SB. Egg and environmental samples were collected day 7- 20 post-inoculation (Trial 1 and 2; excluding weekends) and day 7-27 post-inoculation (Trial 3 and 4; excluding weekends) to detect SB. Recovery on SB was highest in ileocecal tissue samples (11.1-33.3 %; P < 0.05), with little to no recovery in other collected tissue samples. In a small number of shell emulsions (0-2.9 %; P < 0.01), SB was detected. SB was recovered in Trial 1 at a high rate (92.5 %; P < 0.0001) in the substrate composite samples however recovery of Salmonella Braenderup was low in the other egg and environmental samples. These trials indicate that Salmonella Braenderup is not an invasive Salmonella serotype for cage-free laying hens, especially when compared to serotypes of concern to the egg industry. However, it may persist in the environment at low levels.