Submitted to: Poultry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2023
Publication Date: 2/17/2023
Citation: Cosby, D.E., Berrang, M.E., Hinton Jr, A. 2023. Evaluation of a triple buffered peptone broth for detection of Salmonella in broiler feed. Poultry. 2(1):46-53. https://doi.org/10.3390/poultry2010006.
Interpretive Summary: Salmonella continues to be a concern in human illness with poultry and poultry products continuing to be implicated. The actual source of Salmonella entry into the production chain has not be fully elucidated. However, feed and feed ingredients have been shown to carry Salmonella and may be a source of contamination. When feed and feed ingredients are incubated in the current pre-enrichment broths, the pH of the media drop to levels which can injure or kill Salmonella. Using a newly formulated pre-enrichment broth, this study determined the recovery of Salmonella after Salmonella was intentionally spiked at low levels into three enrichment broths with and without feed. Salmonella was able to be recovered from the new broth formulations more often than the other two broths. The new broth will add an additional tool capable of identifying the source of Salmonella contamination in the poultry production system.
Technical Abstract: The pH of pre-enrichment media containing feed/ingredients can become acidic during incubation due to bacterial utilization of feed carbohydrates. This decrease in pH can result in cell injury or death, negatively impacting the detection of Salmonella. Our objective was to evaluate a new triple buffered peptone (TBP) against buffered peptone water (BPW) and lactose broth (LB) for the recovery of Salmonella from feed. Liquid cultures of nalidixic acid resistant strains of Salmonella (Enteritidis, Heidelberg, Kentucky or Typhimurium) were added to the pre-enrichment media alone, pre-enrichment media containing feed or to artificially inoculated feed stored 1 or 7 d to evaluate media effect on the recovery Salmonella. Three replicates per treatment were conducted. After incubation at 37oC for 24 h, the pH of the media was measured prior to plating onto brilliant green sulfa agar plates supplemented with 200 ppm nalidixic acid (BGSNA). Plates were incubated and evaluated for presence of typical Salmonella colonies. The experiment was replicated. TBP was observed to exhibit significantly better buffering capacity than BPW or LB. Additionally, TBP was able to recover Salmonella 100% of the time compared to BPW (97.9%) and LB (61.5%). TBP shows promise to maintain neutral pH during pre-enrichment which may allow for a more accurate detection of Salmonella in feed.