ARS | Publication request: Profiling the gastrointestinal microbiota in response to Salmonella: low versus high Salmonella shedding in the porcine host

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 24, 2012
Publication Date: June 20, 2012
Citation: Bearson, S.M., Allen, H.K., Bearson, B.L., Looft, T.P., Brunelle, B.W., Kich, J.D., Bayles, D.O., Alt, D.P., Levine, U.Y., Stanton, T.B. 2012. Profiling the gastrointestinal microbiota in response to Salmonella: low versus high Salmonella shedding in the porcine host [abstract]. American Society for Microbiology General Meeting, June 16-19, 2012, San Francisco, California. p. 3150.

Technical Abstract: As the leading cause of bacterial foodborne disease in the U.S., Salmonella is a major food safety concern. Endeavors to control Salmonella in our food chain are hindered by the ability of Salmonella to sub-clinically colonize livestock, thereby serving as a significant reservoir for contamination of naïve animals, the environment, and our food supply. Epidemiological surveys of U.S. swine farms indicate that greater than 50% of farms are Salmonella positive. On the farm and in experimental infections, Salmonella colonization, carriage, and shedding in pigs varies greatly. To investigate the dynamics between the porcine intestinal microbiota and Salmonella colonization/persistence in swine, we temporally profiled the microbial communities of pigs classified as low and high Salmonella-shedders. Six-week-old pigs were intranasally inoculated with 109 colony forming units of Salmonella enterica serovar Typhimurium khi4232 (n=60); six litter mates served as mock-inoculated controls. Salmonella shedding was measured by bacteriological evaluation of fecal samples over a 3-week period. DNA was isolated from feces, and the V1-V3 region of the bacterial 16S rRNA gene was PCR amplified and pyrosequenced with bar-coded primers. Quality-controlled sequences were trimmed of barcodes and aligned with reference 16S rRNA gene sequences. At the species-level operational taxonomic unit (OTU) cutoff of 0.03 sequence dissimilarity, significant Salmonella-induced changes were observed in the microbial profiles at 2 and 7 days post-inoculation for both the low-shedder and high-shedder pigs compared to the non-inoculated pigs, as well as between the low-shedders and high-shedders (p less than 0.05). To infer which bacteria were involved in the community shifts, the sequences were assigned to genus-level phylotypes. A significant decrease in the abundance of Prevotella and a significant increase in various genera (e.g. Lactobacillus, Campylobacter, and Oscillibacter) were observed in the high-shedders compared to either non-inoculated or low-shedder pigs (p less than 0.05 after correction for multiple comparisons), suggesting outgrowth of certain genera to occupy the niche vacated by Prevotella. The data indicate a significant correlation between shifts in the intestinal microbiota and Salmonella shedding status in pigs.