Tackling Listeria monocytogenes: Why it is in the news…

Posted by Stacey Garcia, Ph.D. on Jul 13, 2015 3:32:35 PM

listeria_roundListeria monocytogenes is one of the most virulent food-borne pathogens with 20-30% of clinical infections resulting in death1. It can grow in the cold temperature of the refrigerator, and it does not discriminate, as it’s been implicated in produce, dairy, ready-to-eat meats, and even frozen foods. L. monocytogenes outbreaks are challenging to trace back to the source because listeriosis symptoms can take up to 70 days to appear.

Food manufacturers typically utilize a multi-pronged approach to manage L. monocytogenes levels in their plants and products. This approach often consists of two main components:

  • Monitoring some/all Listeria species on plant surfaces
  • Testing specifically for Listeria monocytogenes in products

Both components test for the pathogen, however, each component has a different purpose. Manufacturers may modify this basic approach based on their specific needs, but the benefits of the approach remain the same: testing plant surfaces is a proactive measure of efficacy of mitigation strategies, and testing product provides additional confidence that ingredients or finished product are safe. The two approaches complement each other to help provide a comprehensive picture of the plant environment and product quality.

However, L. monocytogenes can be challenging to detect and monitor because it grows slowly in enrichment media. This can impact pathogen test turnaround times, which may have an impact on operations. When turnaround time and accuracy are critical to operations, it is valuable for manufacturers to assess available pathogen test methods and determine the best fit for them.

Roka Bioscience recently received AOAC validation for cut cantaloupe and queso fresco with its Atlas Listeria monocytogenes LmG2 Detection Assay. The LmG2 assay was previously AOAC-validated for several foods and environmental surfaces, including vanilla ice cream, hot dogs, and deli turkey. Roka also provides a Listeria species assay that has received AOAC validation for several foods and surfaces. The L. monocytogenes combined with the Listeria species Atlas Detection Assays provide flexibility to manufacturers to apply a Listeria monitoring approach that fits their unique needs.

1Ramaswamy V, Cresence VM, Rejitha JS, Lekshmi MU, Dharsana KS, Prasad SP, Vijila HM. (February 2007). "Listeria – review of epidemiology and pathogenesis." (PDF). J Microbiol Immunol Infect. 40 (1): 4–13.

Topics: Listeria monocytogenes