Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 2004
Publication Date: November 15, 2004
Citation: Toscano, M.J., Stabel, T.J., Hurd, S.H., Lay Jr, D.C. 2004. Effect of norepinephrine in the transmission of Salmonella between swine. Proceedings of the Conference of Research Workers in Animal Diseases. p. 107. Technical Abstract: Norepinephrine has been shown to exhibit a potent in vitro influence on gram-negative bacteria virulence and recrudescence, although such a relationship has never been investigated in livestock. To determine the relationship between in vivo and in vitro norepinephrine (NE) exposure on infectious capacity of Salmonella typhimurium in swine, Salmonella was grown in either a NE-infused (NEX) or standard Luri-Bertrani (LB) broth and then used to infect naïve animals. These animals were either transported or not transported immediately before infection (n=6 animals/treatment). Animals were sacrificed at 3-h and 24-h post-infection. Tissue and fecal samples were collected and plated to quantify bacterial concentrations. Statistical analysis using exact tests for small sample sizes was conducted to detect differences in bacterial concentrations relative to culture condition (NEX vs. LB) at each time point, with each sampled tissue. In vitro culture conditions and transportation had a significant effect on the resulting bacteria concentration in a variety of tissues. Interestingly, transportation appeared to reverse the effect of NE exposure on bacterial numbers. For instance, non-transported NEX animals had a greater bacterial concentration in the ileal-cecal lymph node at 24-h than their LB counterparts (3144 +/- 1018 vs.1306 +/- 646 CFU/g of tissue, p<.01, respectively), though the pattern was reversed in transported animals at the same time point (39 +/- 21.8 vs.635 +/- 404 CFU/g of tissue, p<.05, respectively). Though there were exceptions, this pattern was consistent for > 80% of tissues that exhibited a treatment effect. Our results suggest that NE exposure enhances Salmonella's infectious capacity, possibly by expediting key life processes. Such a relationship between NE exposure and infectious capacity may provide bacteria a means to exploit a stress-induced, immune compromised animal and increase the likelihood of infection.