Navigation

P1-44 Evaluation of the DuPont™ BAX® System PCR Assays for Genus Listeria and Listeria monocytogenes for Testing Stainless Steel and Concrete Environmental Surfaces Using 90 Milliliters of Primary Enrichment Media

Sunday, July 26, 2015
Exhibit Hall (Oregon Convention Center)
Teresa Brodeur , DuPont Nutrition & Health , Wilmington , DE
Bridget Andaloro , DuPont Nutrition & Health , Wilmington , DE
Dawn Fallon , DuPont Nutrition & Health , Wilmington , DE
Steven Hoelzer , DuPont Nutrition & Health , Wilmington , DE
Nisha Corrigan , DuPont Nutrition & Health , Wilmington , DE
Julie Weller , DuPont Nutrition & Health , Wilmington , DE
Andrew Farnum , DuPont Nutrition & Health , Wilmington , DE
Pheakdey Ith , DuPont Nutrition and Health , Wilmington , DE
F. Morgan Wallace , DuPont Nutrition & Health , Wilmington , DE
Introduction: Due to increases in industry concern and USDA regulatory policies for environmental Listeria testing in facilities producing Ready-to-Eat meat products, a new importance has been placed on developing rapid Listeria spp. and L. monocytogenes testing methods that are industry-validated, easy to use and cost effective. One way to help support these goals is to develop enrichment protocols that use less media per sample in conjunction with automated PCR testing methods.

Purpose: The purpose of this study was to assess the ability of two commercial PCR assays for Genus Listeria and L. monocytogenes to detect Listeria from stainless steel and concrete environmental surfaces after a modified primary enrichment conducted in 90 ml of Demi-Fraser broth. 

Methods: Stainless steel and concrete surfaces (n = 20 each) were inoculated with L. monocytogenes and L. welshimeri, respectively, at levels likely to give fractional recovery.  Each surface was also inoculated with Enterococcus faecalis as background flora. For the alternative method, sample sponges were added to 90 ml of Demi-Fraser broth and incubated for 22 - 26 h at 30 ± 2°C, then 100 µL of primary enrichment was added to 9.9 ml MOPS-BLEB and incubated for an additional 18 - 24 hours at 35 ± 2°C.  For the reference method, protocols were followed according to the USDA-FSIS MLG method.  All samples were processed in the BAX® System instrument and confirmed according to the reference culture method.

Results: For the alternative enrichment, PCR and culture results were identical with 13 positive samples from stainless steel and 6 from concrete.  The reference method enrichment produced 10 positive samples on stainless steel and 6 on concrete also with identical results from culture and PCR. 

Significance: The alternative and reference methods generated results that were statistically indistinguishable.  These data suggest that the method as modified is an acceptable alternative to the reference method.

Back to: Poster Session 1 – Laboratory and Detection Methods, Low-water Activity; Retail and Food Service Safety; Seafood; Communication Outreach and Education; Produce; Food Toxicology; Non-microbial Food Safety; Food Defense; Microbial Food Spoilage
<< Previous Abstract | Next Abstract >>