Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2016
Publication Date: 8/1/2016
Citation: Cosby, D.E., Cox Jr, N.A., Berrang, M.E., Cason Jr, J.A., Richardson, K.E. 2016. Evaluation of a newly developed triple buffered peptone broth for detection of Salmonella in broiler feed [abstract]. International Association for Food Protection Proceedings. 50:P1-85.
Interpretive Summary: none
Technical Abstract: Lactose broth (LB) and buffered peptone (BP) are used as pre-enrichment media to recover Salmonella from feed. Bacterial utilization of feed carbohydrates results in the production of acidic byproducts causing a drop in the media pH which can injure or kill Salmonella and yield false negative results. The objective of this study was to evaluate a new triple buffered peptone (TBP) against LB and BP for the recovery of Salmonella from inoculated broiler feed. In each of two replications, triplicate 5 g samples of non-medicated broiler feed was individually inoculated with approximately 70 cells/gram of one of four nalidixic acid resistant Salmonella serovars (Enteritidis, Heidelberg, Kentucky or Typhimurium, n=6 per serogroup). Samples were incubated (24h, 37oC) in 45 mL of broth (LB, BP or TBP). After incubation, the pH of the broth was measured and all broths were streaked on brilliant green sulfa agar containing 200 ppm nalidixic acid, incubated overnight at 37oC and evaluated for the presence of typical Salmonella colonies. The mean pH of TBP pre-enrichment media containing feed (6.6) was significantly (P<0.01) higher than BP (5.1) or LB (4.4). Salmonella was recovered from all (24+/24) samples pre-enriched in TBP. All samples (24+/24) pre-enriched in BP yielded positive Salmonella results. However, significantly fewer (P<0.01) samples pre-enriched in LB were found to be positive (2+/24). One positive sample was a S. Typhimurium and one was a S. Heidelberg. Broiler feed pre-enriched in LB or BP suffers a significant decrease in pH during incubation compared to TBP. Pre-enrichment of feed in LB results in lower recover of inoculated Salmonella than either BP or TBP. TBP showed promise as a means to maintain near neutral pH in feed samples during pre-enrichment and may allow the accurate detection of Salmonella in feed and other similar samples.