Skip to main content
ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #403885
Research Project: Holistic Tactics to Advance the Microbiological Safety and Quality of the Red Meat Continuum

Location: Meat Safety and Quality

Title: Identification of actionable sentinels for Salmonella contamination of beef lymph nodes and determining the impact of environmental contamination levels

Author
item Schmidt, John
item FASHENPOUR, ERIN - Kansas State University
item SOLER-DIAZ, RIGO - Texas Tech University
item Harhay, Dayna
item Arthur, Terrance
item Bosilevac, Joseph - Mick
item Wheeler, Tommy
item KANG, QING - Kansas State University
item GRAGG, SARA - Kansas State University
item SANCHEZ-PLATA, MARCOS - Texas Tech University

Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2023
Publication Date: 6/25/2023
Citation: Schmidt, J.W., Fashenpour, E., Soler-Diaz, R., Harhay, D.M., Arthur, T.M., Bosilevac, J.M., Wheeler, T.L., Kang, Q., Gragg, S.E., Sanchez-Plata, M. 2023. Identification of actionable sentinels for Salmonella contamination of beef lymph nodes and determining the impact of environmental contamination levels. [Abstract]. American Meat Science Association Conference Reciprocal Proceedings. No. 117.

Interpretive Summary:

Technical Abstract: Objective: Determine if finishing pen surface soil material samples (SMSs), cecal content swabs (CCSs), or ileocecal lymph nodes (ICLNs) can be used as sentinels for high-levels of Salmonella in beef cattle peripheral lymph nodes (PLNs). Materials and Methods: Four 10-gram SMSs were obtained from each of 100 finishing cattle pens distributed equally across 10 commercial feedyards. Culture methods were used to detect and quantify Salmonella in SMSs. Quantified SMSs were assigned a Salmonella Index (SalI) equal to their log CFU/g value. SMSs that were Salmonella prevalent but below the limits of quantification (2.30 log CFU/g) were assigned a SalI of 1.00. Salmonella prevalence negative SMSs. were assigned a SalI of 0.00. Eight pens with 100% SMS Salmonella prevalence and SMS SalI = 1.00 and 8 pens with SMS SalI = 0.00 were sampled at harvest in commercial beef processing plant. From each of these 16 pens, (CCSs, ICLNs, superficial cervical LNs, popliteal LNs, and subiliac LNs) were obtained from between 20 and 25 randomly sampled carcasses. Salmonella were enumerated and detected using BAX System SalQuant and BAX Real-time PCR Salmonella assays, respectively. Quantified samples were assigned a SalI equal to their log CFU value. Cecal content sponges and LN samples that were Salmonella prevalent but below the limits of quantification (1.76 log CFU/cecal content sample; 1.00 log CFU/LN sample) were assigned SalIs of 0.88 and 0.50, respectively. Salmonella negative samples were assigned a SalI of 0.00. For each pen, the mean of superficial cervical LNs, popliteal LNs, and subiliac LNs SalI was the mean peripheral lymph node (PLN) SalI. Pens with mean PLN SalI = 1.00 were classified as contaminated with high levels of Salmonella. SMSs, CCSs, and ICLNs were each evaluated as possible sentinels for PLNs. Pens with mean sentinel SalI = 1.00 and mean PLN SalI = 1.00 were considered true positives. Pens with mean sentinel SalI = 1.00 and mean PLN SalI < 1.00 were considered false positives. Pens with mean sentinel SalI < 1.00 and mean PLN SalI = 1.00 were considered false negatives. Pens with mean sentinel SalI < 1.00 and mean PLN SalI < 1.00 were considered true negatives. Results: High Salmonella levels (mean SalI = 1.00) were identified in PLNs from 4 pens (Table 1). SMSs from 8 pens had high Salmonella levels including all pens with high PLN Salmonella levels (Table 1). CCSs from 6 pens had high Salmonella levels including 3 of 4 pens with high PLN Salmonella levels. ICLNs from 6 pens had high Salmonella levels including 3 of 4 pens with high PLN Salmonella levels (Table 1). Evaluation of SMSs, CCSs, and ICLNs as Salmonella sentinels for PLNs found specificities were 67%, 75%, and 75% for SMSs, CCSs, and ICLNs, respectively. SMSs, CCSs, and ICLNs had false negative rates of 0%, 25%, and 25%, respectively. False positive rates were 33%, 25%, and 25% for SMSs, CCSs, and ICLNs, respectively. Conclusion: These results suggest that SMSs, CCSs, and ICLNs each could be used to identify pens of cattle with high-levels of Salmonella in PLNs. However, SMS was the only method with no false negative results. Additional research across diverse production environments is needed to confirm these results.