Location: Food and Feed Safety ResearchTitle: Neutral barcoding of genomes reveals the dynamics of Salmonella colonization in cattle and their peripheral lymph nodes
|PORWOLLIK, STEFFEN - University Of California|
|Genovese, Kenneth - Ken|
|CHU, WEIPING - University Of California|
|LONERAGAN, GUY - Texas Tech University|
|MCCLELLAND, MICHAEL - University Of California|
Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2018
Publication Date: 7/1/2018
Publication URL: https://handle.nal.usda.gov/10113/5985420
Citation: Porwollik, S., Genovese, K.J., Chu, W., Loneragan, G.H., Edrington, T.S., McClelland, M. 2018. Neutral barcoding of genomes reveals the dynamics of Salmonella colonization in cattle and their peripheral lymph nodes. Veterinary Microbiology. 220:97-106. https://doi.org/10.1016/j.vetmic.2018.05.007.
Interpretive Summary: Cattle were intradermally injected with tagged strains of Salmonella that were then tracked in the cattle using a new sequence analysis system in cattle lymph nodes, feces, and organs. The findings show that many Salmonella colonize the gut at one time, but very few colonize the peripheral lymph nodes at one time. It was found that Salmonella rarely move from the peripheral lymph nodes to the gastrointestinal tract. It was also found that Salmonella do not undergo much multiplication in sites other than the gastrointestinal tract. Results from this work have important implications for understanding the dynamics of Salmonella colonization of cattle and for the development of improved protocols and procedures to make beef products as safe as possible for the consumer.
Technical Abstract: Feedlot cattle often contain Salmonella. The number of bacteria that initiate colonization of different cattle organs and the bacterial migration within these large animals are poorly understood. To investigate these questions, we constructed wild-type isogenic tagged strains (WITS) of Salmonella by inserting 21-base barcodes flanked by Illumina sequencing primers into a neutral genome location. We then delivered several different pools of uniquely barcoded clones orally and into multiple intradermal sites, in individual Holstein steers, and sub-sequently performed Salmonella-directed sequence tag-based analysis of microbial populations (STAMP). Using high-throughput sequencing of the barcodes of Salmonella grown from steer lymph nodes, organs and feces, we monitored how individual barcoded clones travel from different entry sites within animals. Data showed that gastrointestinal colonization was established by up to hundreds of Salmonella founder cells, whereas peripheral lymph nodes were usually colonized by very low numbers of founding bacteria, often originating from the nearest draining intradermal delivery site. Transmission of Salmonella from the gastrointestinal tract to the lymphatic system was frequently observed, whereas entry of intradermally delivered bacteria into the gut was rare. Bacteria undergo limited extraintestinal proliferation within or prior to arrival at peripheral lymph nodes. Overall, the application of the STAMP technique facilitated characterization of the migration routes and founder population size of Salmonella within feedlot cattle and their organs and lymph nodes in unprecedented detail.