P2-13 Validation Study of a Real-time PCR-based Method for the Detection of Salmonella in a Broad Range of Food Matrices and Environmental Surfaces

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Patrice Arbault , NEXIDIA SAS, Rue de Mayence 15, 21000 , Dijon , France
Sylvie Hallier-Soulier , Pall GeneDisc Technologies , Bruz , France
Sebastien Bouton , Pall GeneDisc Technologies , Bruz , France
Sirine Assaf , Pall GeneDisc Technologies , Bruz , France
Christelle Nahuet , Pall GeneDisc Technologies , Bruz , France
Patrick Bird , Q Laboratories, Inc. , Cincinnati , OH
Erin Crowley , Q Laboratories, Inc. , Cincinnati , OH
Introduction: Salmonella is one of the most important microbiological criteria inspected routinely by food business operators and national authorities. Since reference methods usually rely on exhaustive and cumbersome procedures, lab operators use alternate methods offering shorter time to results and simpler enrichment and assay protocols. Nonetheless, such alternate analytical methods require official validation studies in order to demonstrate equivalency performances between alternate and reference methods. 

Purpose: The objective of this study was to evaluate the Pall GeneDisc® Plate Salmonella spp., a PCR-based method for the detection of Salmonella in various test portions (25 g and 375 g) of a broad range of food and environmental surfaces in comparison to reference methods using the current AOAC-PTM guidelines.

Methods: The evaluation consisted of method comparison of 19 different food matrices (ground beef, beef trim, raw chicken, ground turkey, chicken carcass rinses, raw shrimp, lettuce, fresh cut cantaloupe, whole cantaloupe, peanut butter, beansprouts, spent irrigation water, dry milk, cheddar cheese, ice cream, milk chocolate, dry pet food, black pepper and shell eggs) and 2 environmental surfaces (rubber and stainless steel).  The performances of the alternate assays were compared to USDA/FSIS MLG 4.05 and FDA/BAM Chapter 5. 

Results: All samples enriched (N = 1,125) and assayed with the alternate Salmonella method were culturally confirmed by the various confirmation procedures (alternate and reference methods). For food matrices with high competing flora (poultry products, beansprouts, carcass rinsates) or with presence of inhibitory compounds (black pepper), some samples required a subculture of the BPW in selective enrichment broths (TT and RV) in order presumptive positive PCR results can be clearly confirmed. The statistical analysis with POD (Probability of Detection) showed the alternate method to be as good as the USDA and FDA reference methods.  

Significance: This molecular method was shown reliable for the detection of Salmonella in various food matrices.