Rapid Quantitative Method Development for Beef and Pork Lymph Nodes Using BAX® System Real Time Salmonella Assay

David A Vargas; Gabriela K Betancourt-Barszcz; Sabrina E Blandon; Savannah F Applegate; Mindy M Brashears; Markus F Miller; Sara E Gragg; Marcos X Sanchez-Plata

doi:10.3390/foods12040822

Rapid Quantitative Method Development for Beef and Pork Lymph Nodes Using BAX^® System Real Time Salmonella Assay

Foods. 2023 Feb 15;12(4):822. doi: 10.3390/foods12040822.

Authors

David A Vargas¹, Gabriela K Betancourt-Barszcz¹, Sabrina E Blandon¹, Savannah F Applegate², Mindy M Brashears¹, Markus F Miller¹, Sara E Gragg³, Marcos X Sanchez-Plata¹

Affiliations

¹ International Center for Food Industry Excellence, Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409, USA.
² HygienaTM, 2 Boulden Circle, New Castle, DE 19720, USA.
³ Department of Animal Science & Industry, Kansas State University, Manhattan, KS 66506, USA.

Abstract

The goal of this study was to develop a rapid RT-PCR enumeration method for Salmonella in pork and beef lymph nodes (LNs) utilizing BAX^®-System-SalQuant^® as well as to assess the performance of the methodology in comparison with existing ones. For study one: PCR curve development, pork, and beef LNs (n = 64) were trimmed, sterilized, pulverized, spiked with 0.00 to 5.00 Log CFU/LN using Salmonella Typhimurium, and then homogenized with BAX-MP media. Samples were incubated at 42 °C and tested at several time points using the BAX^®-System-RT-PCR Assay for Salmonella. Cycle-Threshold values from the BAX^®-System, for each Salmonella concentration were recorded and utilized for statistical analysis. For study two: Method comparison; additional pork and beef LNs (n = 52) were spiked and enumerated by (1) 3M™EB-Petrifilm™ + XLD-replica plate, (2) BAX^®-System-SalQuant^®, and (3) MPN. Linear-fit equations for LNs were estimated with recovery times of 6 h and a limit of quantification (LOQ) of 10 CFU/LN. Slopes and intercepts for LNs using BAX^®-System-SalQuant^® when compared with MPN were not significantly different (p < 0.05), while the same parameters for 3M™EB-Petrifilm™ + XLD-replica plate were significantly different (p > 0.05). The results support the capability of BAX^®-System-SalQuant^® to enumerate Salmonella in pork and beef LNs. This development adds support to the use of PCR-based quantification methodologies for pathogen loads in meat products.

Keywords: Salmonella quantification; beef lymph nodes; pathogen control; pork lymph nodes.

Grants and funding

This study was funded by in-kind contributions from Hygiena and the International Center for Food Industry Excellence (ICFIE) at Texas Tech University.