P2-208 Detecting Listeria monocytogenes in Mozzarella Cheese with the BAX® System Real-time PCR Assays for Genus Listeria and L. monocytogenes Using 24 LEB Complete Media

Tuesday, July 11, 2017
Exhibit Hall (Tampa Convention Center)
Nisha Corrigan , Qualicon Diagnostics, LLC, A Hygiena Company , Wilmington , DE
Teresa Brodeur , * , Wilmington , DE
Julie Weller , Qualicon Diagnostics, LLC, A Hygiena Company , Wilmington , DE
Andrew Farnum , Qualicon Diagnostics, LLC, A Hygiena Company , Wilmington , DE
Pheakdey Ith , Qualicon Diagnostics, LLC, A Hygiena Company , Wilmington , DE
Troy Ayers , Qualicon Diagnostics, LLC, A Hygiena Company , Wilmington , DE
Introduction: Listeria species, including Listeria monocytogenes, are psychrotrophic bacterial pathogens capable of growing and multiplying under low temperatures. This characteristic has particularly impacted the dairy industry, which relies on cold temperatures to maintain product quality during extended storage. For this reason, reliable microbiological testing methods are needed to prevent Listeria-related illnesses associated with the consumption of contaminated milk and other dairy products.

Purpose: The purpose of this study was to assess the ability of two real-time PCR assays to detect L. monocytogenes in mozzarella cheese enriched in 24 LEB Complete media.

Methods: Mozzarella cheese (n=20) was artificially inoculated with L. monocytogenes to obtain fractional recovery in 125g portions and held at 4°C for 72 hours to cold stress the target organism. Samples were homogenized with 1,125 mL pre-warmed (35°C) 24 LEB Complete media and incubated at 35°C for 22-26 hours. After incubation, all samples were analyzed by real-time PCR and confirmed using the reference culture method.

Results: The real-time PCR assays for Genus Listeria and L. monocytogenes detected all 10 culture positive samples after 22 hours of enrichment in 24 LEB Complete media.

Significance: The results of this study demonstrated no significant statistical difference between the real-time PCR detection method and the reference culture method to detect Listeria spp. and L. monocytogenes in 125g of mozzarella cheese.