Listeria monocytogenes: The Evolution of Testing Methods

Posted by Mandi Kim, Food Safety Specialist on Jun 30, 2014 9:00:00 AM

An increasing number of foods are being resourced from vast global origins, presenting the risk for food borne pathogens and threatening to undermine the quality and integrity of our food supply. As anyone on the frontlines of food production and testing can tell you, Listeria monocytogenes is a pervasive culprit that requires us to dig deep and find practical, innovative solutions that will “seek and destroy” this pathogen.

As the only pathogenic member of the genus Listeria, L. monocytogenes is commonly associated with the disease listeriosis and is the third leading cause of death among all food borne pathogens. While reduction of listeriosis incidence continues to be a challenge in the United States, advances in technology have led to the development of new food safety testing methods. Such technological advances provide the food safety industry with the tools needed to more rapidly and accurately assess risk and deliver safe and wholesome products.

Listeria species (listeria spp.) are widespread in today’s environment. They can grow in challenging environmental conditions such as low temperatures, low water activity and in high salt concentrations. Environmental testing provides food processors with the information needed to monitor sanitation effectiveness and determine the potential for contamination with pathogenic L. monocytogenes. Listeria monocytogenes’ ability to thrive during post lethality processing and survive in difficult environmental circumstances stresses the critical need for highly accurate and reliable testing.

Historically, food testing has evolved through three major eras of technology. All three methods are used when testing for L. monocytogenes on finished food products as well as for Listeria spp. on environmental surfaces:

  1. Culture Testing: the method to detect pathogens via incubation and selective growth of the target organism in a specific culture media
  1. Immunoassay Testing: the method to detect pathogens through a highly specific antibody-antigen reaction for the target organism 
  1. Molecular Testing: the method to detect pathogens via extraction, amplification and detection of target organism DNA or RNA

The advantages associated with molecular techniques are driving more laboratories away from conventional methods and towards the adoption of molecular testing. In addition to improved accuracy, rapid molecular techniques are ultimately reducing costs to food processing companies and getting safe products to market faster.

The Atlas® Listeria monocytogenes LmG2 Detection Assay is one such molecular tool used in the detection of L. monocytogenes. Recently granted AOAC PTM status, the LmG2 detection assay provides a fast and accurate screening for L. monocytogenes from selected food matrices and together with Roka’s other Atlas Detection Assays, offers a comprehensive and standardized food pathogen testing solution. Read more about Roka’s LmG2 detection assay in Inside Laboratory Management magazine.

Topics: Listeria monocytogenes