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

Area of Science:

• Food Microbiology
• Molecular Diagnostics
• Veterinary Public Health

Background:

• Accurate enumeration of bacterial pathogens like Salmonella in meat products is crucial for food safety.
• Traditional methods for Salmonella detection can be time-consuming, delaying response to potential contamination.
• Development of rapid and reliable quantification techniques is essential for effective pathogen load assessment in meat.

Purpose of the Study:

• To develop and validate a rapid real-time quantitative PCR (RT-PCR) method for Salmonella enumeration in pork and beef lymph nodes.
• To utilize the BAX®-System-SalQuant® assay for this purpose.
• To compare the performance of the developed RT-PCR method against existing standard methods.

Main Methods:

• Study one involved spiking pork and beef lymph nodes with known concentrations of Salmonella Typhimurium and analyzing them using the BAX®-System-RT-PCR Assay to develop PCR curves.
• Study two compared the BAX®-System-SalQuant® method with traditional methods: 3M™EB-Petrifilm™ + XLD-replica plate and Most Probable Number (MPN).
• Method performance was evaluated based on recovery times, limit of quantification (LOQ) of 10 CFU/LN, and statistical comparison of slopes and intercepts.

Main Results:

• The BAX®-System-SalQuant® method demonstrated a limit of quantification of 10 CFU/LN with a recovery time of 6 hours.
• Statistical analysis showed no significant difference (p < 0.05) in slopes and intercepts between the BAX®-System-SalQuant® and MPN methods for lymph nodes.
• In contrast, the 3M™EB-Petrifilm™ + XLD-replica plate method showed significant differences (p > 0.05) compared to MPN.

Conclusions:

• The BAX®-System-SalQuant® assay is capable of accurately enumerating Salmonella in pork and beef lymph nodes.
• This RT-PCR-based quantification methodology provides a rapid and reliable alternative for assessing pathogen loads in meat products.
• The findings support the broader adoption of PCR-based quantification techniques in routine food safety testing.