Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 2010
Publication Date: July 11, 2010
Citation: Hannah, J.F., Wilson, J.L., Cox Jr, N.A., Richardson, L.J., Cason Jr, J.A., Buhr, R.J. 2010. Colonization of marker and field strains of Salmonella Enteritidis and Typhimurium in antibiotic treated and non-treated laying hen . Poultry Science. Technical Abstract: In each of three trials, caged laying hens (76, 26, and 33 wk-of-age) were divided into 6 groups designated to receive either maker (nalidixic acid resistance) S. Enteritidis (SE-M), field S. Enteritidis (SE-F), or marker S. Typhimurium (ST-M), and half pretreated with vancomycin (VNC) (n=12). VNC treated hens received 0.5 mL for 5 d to inhibit Gram-positive bacteria. On d 6, all hens were challenged orally, intravaginally, and intracolonally with Salmonella and placed into separate floor pens. Two wk post-inoculation, all hens were euthanized and samples aseptically collected from the ceca, spleen, liver/gallbladder (LGB), upper (URT) and lower (LRT) reproductive tracts, and ovarian follicles, and analyzed for Salmonella. Among tissues sampled, there were no significant differences (P>0.05) in SE-M, SE-F, and ST-M colonization between VNC pretreated and non-pretreated hens. For the ceca, spleen, and LGB samples, SE-F (83, 100, and 100%) and ST-M (100, 73, and 91%) colonization was significantly greater than SE-M (8, 0, and 8%) colonization in non-pretreated hens. For VNC pretreated hens, SEF (92, 92, and 83%) and ST-M (100, 75, and 83%) colonization among ceca, spleen, and LGB samples was significantly greater than SE-M (36, 0, and 0%) colonization. Overall prevalence of Salmonella in the LRT samples was relatively low, ranging from 8-42% and SE-F and ST-M were isolated from 8 and 18% URT samples, respectively. Only SE-F (8-17%) was isolated from the follicles. The VNC pretreatment had no significant effect on the colonization of SE-M, SE-F, or ST-M. Although SE-M did not colonize as well as SE-F and ST-M, it is not possible to attribute the decreased colonization ability of SE-M solely to the bacterial strain or the induction of nalidixic acid resistance. Additional research will evaluate the potential for a genetic basis for these results.