Droplet Digital Polymerase Chain Reaction Assay for Quantifying Salmonella in Meat Samples.

Area of Science:

• Food Microbiology
• Molecular Diagnostics
• Food Safety Science

Background:

• Salmonella is a major foodborne pathogen causing salmonellosis globally.
• Accurate quantification of Salmonella is crucial for microbiological criteria and risk assessments.
• Traditional methods like plate count and most probable number (MPN) are time-consuming and labor-intensive.

Purpose of the Study:

• To develop and validate a novel droplet digital PCR (ddPCR) assay for the rapid and accurate quantification of Salmonella.
• To evaluate the performance of the ddPCR assay compared to conventional methods.

Main Methods:

• Development of a ddPCR assay targeting the invA gene of Salmonella.
• Validation of the assay's specificity, sensitivity, and limit of quantification in meat samples.
• Comparison of ddPCR results with traditional plate counting and mathematical modeling of growth kinetics.

Main Results:

• The ddPCR assay demonstrated high specificity and sensitivity.
• The limit of quantification was determined to be 1.1 × 10^2 colony-forming units/mL in meat samples.
• Strong linear correlation (R^2 > 0.99) was observed between ddPCR and plate count measurements, with a high correlation coefficient (0.996) in growth kinetics modeling.

Conclusions:

• Droplet digital PCR (ddPCR) is a viable and powerful alternative to the MPN method for Salmonella quantification.
• The developed ddPCR assay provides a rapid, specific, and sensitive tool for quantitative risk assessment in food safety.