P3-21 ISO 16140 Extension Study of the a Method for Detection of Salmonella in 375 g Raw Beef and Raw Veal Samples

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Melinda Maux, Eurofins IPL Nord, Lille, France
Alice Peplinski, Eurofins IPL Nord, Lille, France
Peggy Nomade, bioMérieux, Marcy L'Etoile, France
Jean-Louis Pittet, bioMérieux, Marcy L'Etoile, France
Introduction: The VIDAS® UP Salmonella (SPT) assay is a specific phage protein ligand assay performed in the automated VIDAS instrument in conjunction with a 1-step enrichment procedure. The method has previously been ISO 16140 certified by AFNOR Certification for detection of Salmonellain all 25 g food samples.

Purpose: The objective of this study was to extend the application to 375 g sample size of raw beef and raw veal samples .

Methods: Samples (375 g), ¼ diluted in pre-warmed supplemented Buffered Peptone water, were enriched for 22-26 hours at 41.5±1°C. Two protocols were tested, one with the addition of vancomycin and the other with the addition of the proprietary salmonella supplement. After incubation, samples were boiled for 5 ±1 minutes before performing the assay. All presumptive positive samples were further confirmed after streaking on a chromogenic agar plate. This new method was compared with the ISO 6579 reference method, according to the ISO 16140 standard.

Results: In the comparative study, 63 confirmed positive samples were detected by the new method and 66 with the reference method. No statistically significant difference (X2 < 3.84) was observed between both the methods.  Using spiked samples with a strain of Salmonella Ohio, the 50% level of detection was found between 0.3 and 0.9 CFU/375g for the reference method and between 0.2 and 0.8 CFU/375g for the immunoassay method.

Significance: The results of this study demonstrated equivalence of the method with the traditional reference methods for the detection of Salmonella in 375g raw beef and raw veal samples. The ¼ dilution of the matrix into the enrichment broth is an advantage in terms of cost, handling weight for the technician and requirement of space in the incubator.