Investigation of the Diversity of Antibiotic Resistance Genes and Mobile Genetic Elements in Salmonella associated with U.S. Food Animals

Authors: MCMILLAN, ELIZABETH - University Of Georgia; GUPTA, SUSHIM - Oakland Research Institute; JOVE, THOMAS - Hospital And University Center Of Limoges; Jackson, Charlene; MCCLELLAND, MICHAEL - University Of California; Frye, Jonathan

Submitted to: UJNR Food & Agricultural Panel Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: With the emergence of antibiotic resistance (AR), multidrug resistance (MDR), and carbapenem resistant Enterobacteriaceae (CRE), the specter of widespread untreatable bacterial infections threatens human and animal health. The ability of these emerging resistances to transfer between bacteria on mobile genetic elements (MGEs) could cause the rapid establishment of MDR bacteria in animals leading to a foodborne risk to humans. To investigate this, we identified AR genes, plasmids, and integrons in the genomes of Salmonella enterica isolated from animal sources. Salmonella enterica (n=193) isolated from beef and dairy cattle, chicken, swine, turkey, and their meat products representing 75 diverse serovars were selected based on their differing AR phenotypes. Isolates were sequenced using an Illumina HiSeq. Most isolates contained plasmids, integrons, or both encoding AR or MDR. Many of the mobile elements and AR genes have been previously found in Salmonella; however, they are arranged differently and have not previously been found in animal-associated isolates or in the serovars analyzed. The identification of AR genes, plasmids, and integrons on the same DNA contigs demonstrates physical linkage of MGEs and AR in these food animal-associated Salmonella. This begins to reveal the complexity of AR and MGE assembly and spread among Salmonella in the food animal environment, and demonstrates that different AR genes and MGEs are found in animal isolates as compared to human isolates likely indicating that different factors may be affecting the development and spread of AR in Salmonella in animals. The next step will be to identify environments that lead to the development and spread of AR in animals so that these can be targeted with interventions to reduce this risk to human and animal health.