Use of selective pre-enrichment in assessing salmonella presence during broiler processing

Authors: RASAMSETTI, SURENDRA - University Of Georgia; Berrang, Mark; Cox Jr, Nelson; SHARIAT, NIKKI - University Of Georgia

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2022
Publication Date: 6/1/2022
Citation: Rasamsetti, S., Berrang, M.E., Cox Jr, N.A., Shariat, N. 2022. Use of selective pre-enrichment in assessing salmonella presence during broiler processing. Poultry Science. https://doi.org/10.1016/j.psj.2022.101949.
DOI: https://doi.org/10.1016/j.psj.2022.101949

Interpretive Summary: Salmonella is a food borne bacterial pathogen that is commonly traced to mishandled chicken meat. Traditional cultural methods to detect and isolate Salmonella from chicken products take 5 days to complete. Earlier, we developed a method that combined the first two steps in traditional Salmonella culture to lessen the time required by 24 h. Herein we test that method by sampling processing drip water from 500 broiler carcasses at two processing points in two replication in each of three commercial broiler slaughter plants. Our results show that the improved shorter method works as well as the traditional 5 day method. Both methods detected the same prevalence and serotypes of Salmonella. The new method will be useful to poultry industry processors and their governmental regulators as they work to lessen the risk of human illness by monitoring the salmonella status of chicken and chicken meat products.

Technical Abstract: Conventional Salmonella surveillance requires a week for isolation, confirmation, and subsequent serotyping. We previously showed that this time burden could be reduced by 24 hours by combining the pre-enrichment and enrichment steps to assess Salmonella prevalence in broiler carcasses directly after picking. This was done by adding some selective components from the traditional Rappaport-Vasilliadis (RV) and tetrathionate (TT) selective Salmonella enrichment broths to the non-selective neutralizing buffered peptone water (nBPW) pre-enrichment after four hours of pre-enrichment in nBPW alone. We found good concordance between the two culture methods and in the present study we sought to investigate the efficacy of selective pre-enrichment to isolate Salmonella at five different points during broiler processing. Duplicate carcass drip samples, each representative of 500 broiler carcasses, were collected by catching processing water drip under moving carcass shackle lines in each of three commercial broiler slaughter plants. Samples were collected post-pick, post-inside-outside body wash (IOBW), and post-chill; duplicate wing rinses were performed pre- and post-antimicrobial parts dip. Each processing plant was sampled six times for a total of 180 samples collected. The number of positives identified with selective pre-enrichment condition(48/180) was similar to traditional selective enrichment culture conditions (52/180) (Fisher’s exact test, P = 0.72). Importantly, the incidence of Salmonella reduced dramatically after antimicrobial intervention (post pick 67 % vs. post chill 8.3%). Collectively, these results suggest that a selective pre-enrichment step reduces the time required for Salmonella isolation without negatively affecting detection. We detected four different Salmonella serovars, Kentucky, Infantis, Schwarzengrund, and Typhimurium using CRISPR-SeroSeq, and their incidence rose between post-pick and post-IOBW. The relative abundance of Infantis within individual samples increased between post-pick and post-IOBW while the relative abundance of the other three serovars decreased.