Related Experiment Video
Updated: Aug 23, 2026
Modified Most Probable Number Assay to Quantify Salmonella in Raw and Ready-to-Cook Chicken Products
Published on: January 31, 2025
Multicenter validation of PCR-based method for detection of Salmonella in chicken and pig samples
Burkhard Malorny1, Nigel Cook, Martin D'Agostino
1Federal Institute for Risk Assessment, National Salmonella Reference Laboratory, Diedersdorfer Weg, Berlin, Germany.
Abstract:
As part of a standardization project, an interlaboratory trial including 15 laboratories from 13 European countries was conducted to evaluate the performance of a noproprietary polymerase chain reaction (PCR)-based method for the detection of Salmonella on artificially contaminated chicken rinse and pig swab samples. The 3 levels were 1-10, 10-100, and 100-1000 colony-forming units (CFU)/100 mL. Sample preparations, including inoculation and pre-enrichment in buffered peptone water (BPW), were performed centrally in a German laboratory; the pre-PCR sample preparation (by a resin-based method) and PCR assay (gel electrophoresis detection) were performed by the receiving laboratories. Aliquots of BPW enrichment cultures were sent to the participants, who analyzed them using a thermal lysis procedure followed by a validated Salmonella-specific PCR assay. The results were reported as negative or positive. Outlier results caused, for example, by gross departures from the experimental protocol, were omitted from the analysis. For both the chicken rinse and the pig swab samples, the diagnostic sensitivity was 100%, with 100% accordance (repeatability) and concordance (reproducibility). The diagnostic specificity was 80.1% (with 85.7% accordance and 67.5% concordance) for chicken rinse, and 91.7% (with 100% accordance and 83.3% concordance) for pig swab. Thus, the interlaboratory variation due to personnel, reagents, thermal cyclers, etc., did not affect the performance of the method, which will be proposed as part of a developing international PCR standard.
Insights
A European interlaboratory trial validated a novel polymerase chain reaction (PCR) method for Salmonella detection in food. The method demonstrated high diagnostic sensitivity and specificity, paving the way for an international PCR standard.
Area of Science:
- Food Microbiology
- Molecular Biology
- Analytical Chemistry
Background:
- Standardization of molecular methods is crucial for reliable food safety testing.
- Polymerase chain reaction (PCR) offers a rapid and sensitive approach for pathogen detection.
- Previous methods for Salmonella detection required extensive validation across multiple laboratories.
Purpose of the Study:
- To evaluate the performance of a non-proprietary PCR-based method for Salmonella detection.
- To assess the method's accuracy and reproducibility in an interlaboratory trial.
- To determine the suitability of the method for international standardization.
Main Methods:
- An interlaboratory trial involving 15 laboratories across 13 European countries.
- Artificially contaminated chicken rinse and pig swab samples were used.
- Sample preparation involved buffered peptone water (BPW) pre-enrichment, followed by resin-based pre-PCR preparation and PCR assay with gel electrophoresis detection.
Main Results:
- The PCR method achieved 100% diagnostic sensitivity for both chicken rinse and pig swab samples.
- Diagnostic specificity was 80.1% for chicken rinse and 91.7% for pig swab.
- High accordance (repeatability) and concordance (reproducibility) were observed, indicating minimal interlaboratory variation.
Conclusions:
- The evaluated non-proprietary PCR method is highly effective for Salmonella detection in food matrices.
- The method's robust performance across different laboratories supports its adoption as an international standard.
- This standardization effort enhances the reliability and consistency of Salmonella testing in food safety surveillance.
