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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #391259

Research Project: Holistic Tactics to Advance the Microbiological Safety and Quality of the Red Meat Continuum

Location: Meat Safety and Quality

Title: Characterization and comparison of Salmonella spp. isolated from the mesenteric lymph nodes of cattle and the feedlot environment

item Schmidt, John
item HABIB, KELLEN - Kansas State University
item NICHOLS, CODY - Legacy Animal Nutrition
item Arthur, Terrance
item Bosilevac, Joseph - Mick
item GRAGG, SARA - Kansas State University
item Harhay, Dayna

Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Cattle lymph nodes (LNs) harbor Salmonella and understanding if a relationship exists between environmental and LN contamination is important for identifying mitigation strategies to protect public health. Purpose: This study aimed to characterize Salmonella spp. isolated from the mesenteric lymph nodes (MLNs) and feedlot environment of cattle to probe at a possible relationship between environmental and MLN contamination. Methods: Samples were collected from water troughs (WT) and pen surfaces (PS; dirt floor) at the feedlot of a convenience sample (N=2,160) of cattle enrolled in a commercial feeding trial, and MLNs (N=427) were collected at harvest. Environmental samples were enumerated on xylose lysine desoxycholate (XLD) agar+antibiotics, while MLNs were enumerated on Enterbacteriaceae petrifilm® replica plated to XLD. Samples underwent immunomagnetic separation, secondary enrichment in Rappaport-Vassiliadis broth, and isolation plating on XLD. Isolates were serotyped and subjected to multiplex PCR to identify and quantify up to 7 virulence genes, indicating Highly Pathogenic Salmonella (HPS) serotype designations (HPS1-7). Results: Salmonella was detected in 98.6%, 50%, and 13.8% of PS, WT, and MLN samples, respectively. Salmonella in PS ranged from 200-5,200 CFU/g, with 29.2% =200 CFU/g. Anatum HPS3, Lubbock HPS4, and Montevideo HPS4 were most frequently detected from PS and WT, while MLNs most frequently harbored Lubbock HPS4, Montevideo HPS1, and HPS4, with Anatum HPS3 also commonly recovered. Pens with enumerable levels of Salmonella in PS were more likely to have Salmonella isolated from corresponding WTs, than those with lower levels of Salmonella. Some Salmonella subtypes were recovered from MLNs but not from the environment. Significance: These data raise additional questions about point of cattle LN contamination, duration/persistence of Salmonella in LNs, and suggest that Salmonella in LNs may not reflect prevalence and subtypes detected in the most proximal environment prior to harvest. These questions must be addressed to effectively mitigate LN contamination.