AOAC RI ERP Final Action Recommendations eBook

FINAL (Version 4)

DuPont™ BAX ® System Real-Time PCR Assay for Salmonella : Collaborative Study

Introduction

1 Salmonella is a leading cause of foodborne illness. The low infectious dose of the bacterium makes it 2 critical to detect even low concentrations of the Salmonella in foods. Additionally, the presence of high 3 concentrations of closely related non-pathogenic bacteria create the need for highly accurate 4 methodologies. Traditionally, labs concerned with detection of Salmonella screened food samples with 5 culture methods, such as those provided by the United States Department of Agriculture Food Safety 6 and Inspection Service (USDA-FSIS) and the U. S. Food and Drug Administration’s (FDA), which require 7 several days to detect and confirm Salmonella . Rapid methods of screening for Salmonella have been 8 developed, but these generally require two days of enrichment. By contrast, the DuPont™ BAX® System 9 detects the pathogen less than 90 minutes after enrichment, and the DNA-based results are both 10 reliable and reproducible, leading to quicker release of cleared product. 11 The BAX® System Real-Time PCR Assay for Salmonella was certified by the AOAC Research Institute in 12 August, 2012 and designated Performance Tested Method SM (PTM) #081201. No significant differences 13 were reported for detection of Salmonella in the matrices tested when comparing the BAX® System 14 method results to the standard reference culture procedures described in the U.S. Department of 15 Agriculture-Food Safety and Inspection Service Microbiological Laboratory Guidebook (USDA-FSIS MLG) 16 [1], U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) [2], and Health 17 Canada Compendium of Analytical Methods (HC CAM) [3]. The matrices validated in the PTM study 18 included raw ground beef (85% lean, 25 g and 375 g), chicken carcass rinse, cream cheese, fresh bagged 19 lettuce, dry pet food, and stainless steel. Inclusivity testing demonstrated that the BAX® System method 20 was reactive with 317 Salmonella isolates, representing over 100 different serotypes. The test method 21 did not detect 37 different non- Salmonella strains tested. 22 Following the completion of the PTM study, a pre-collaborative study was conducted on an additional 18 23 matrices, including ground beef with soy (85% lean), beef trim, frankfurters (beef), shrimp, ground 24 turkey, chicken wings, dried eggs (whole, powdered), shell eggs, frozen peas, orange juice, instant 25 nonfat dry milk, ice cream (12% fat), peanut butter, cocoa (unsweetened), white pepper, milk-based 26 infant formula, ceramic tile, and plastic surfaces. The results obtained using the test method indicate no 27 statistical difference with the reference method when compared to the corresponding reference 28 method results. 29 In addition, two of the pre-collaborative study matrices – frankfurters (pork plus turkey) and orange 30 juice(pasteurized not-from-concentrate) – were evaluated in a total of 15 independent laboratories as 31 part of the collaborative study to demonstrate repeatability of the internal laboratory results 32 independent of the end user. The results obtained using the test method indicate no statistical 33 difference when compared to the corresponding reference method results. 34 35 Collaborators analyzed 2 representative matrices (pork and turkey frankfurters and pasteurized, not- 36 from-concentrate orange juice without pulp) at 3 contamination levels (low, high and un-inoculated) 37 comparing the performance of the BAX® System Real-Time PCR Assay for Salmonella to appropriate 38 Study Design

DuPont Nutrition & Health

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