Good-bye to bad bugs

Prevent Listeriosis through smarter testing

A test from 3M Molecular Detection System uses a combination of LAMP and bioluminescence detection technologies, resulting in a simpler, more robust DNA amplification and detection method.

John David 3MBy John M. David, 3M

Listeriosis is a very serious foodborne illness caused by Listeria monocytogenes. While rare, primarily affecting high-risk groups including pregnant women, newborns and immune-compromised individuals, the mortality rate is very high as compared to other foodborne diseases. Just last year in the United States, a Listeria outbreak associated with Italian-imported ricotta salata cheese sickened 22 people, including four deaths.

Dairy foods processors must be especially diligent in their efforts to combat Listeria, as it has been found in pasteurized or unpasteurized milk products, including soft cheeses made such as queso fresco, Brie, Feta and Camembert.

Listeria monocytogenes is a resilient organism

L. monocytogenes is found virtually everywhere in the environment, including soil, water and certain animals. It is a resilient organism, surviving in a broad range of environmental conditions. Unlike other foodborne bacteria, L. monocytogenes can grow at refrigeration temperatures and even at less than 1°C (34 °F), contributing to its ability to cause disease and high risk for certain refrigerated and ready-to-eat foods. Although pasteurization does kill the bacterium, contamination may still occur during the packaging process and processors must be vigilant in their prevention and testing procedures.

Fortunately, thorough and regular plant cleanings that follow HACCP and good manufacturing practices are highly effective in reducing the presence of Listeria. The pathogen can be transferred between sites inside a plant via human activity, so floors, drains, pallets, equipment and even cleaning supplies must be cleaned properly to prevent cross-contamination. And of course, enforcing proper personal protective equipment and employee hygiene, such as regular hand washing, should not be overlooked.

Clean, sample and test for Listeria in a dairy processing plant

Listeria monocytogenes contamination has been found in many types of food processing plants, and in some cases has been show to persist in the environment for years. While proper cleaning and sanitation is crucial, no food safety program is complete without an effective sampling and testing plan to ensure the absence of harmful pathogens. This can be a combination of environmental monitoring and product testing. Regular sampling should occur over a ranged of sites and/or product types, and location and frequency will depend on the layout of the premises, product flow, amount of product produced, and other factors.

As food processors require faster turn-arounds to meet the pace of today’s needs, testing strategies have shifted from slower, traditional culture-based methods to more rapid detection methods. Technologies using nucleic acid amplification have revolutionized the detection of foodborne pathogens from food or environmental samples by providing highly rapid and specific detection. While many molecular methods have utilized polymerase chain reaction (PCR) technology, advances in molecular biology have resulted in newer, robust technologies including loop mediated isothermal amplification (LAMP). A widely recognized method for rapid molecular amplification, LAMP has now been cited in nearly 1,000 scientific articles and has been recognized for its ability to reliably and efficiently target DNA compared to conventional PCR methods.

While PCR uses thermal cycling, i.e., alternating heating and cooling steps to enzymatically amplify DNA, LAMP uses isothermal amplification – amplification at a constant temperature. Using multiple primers to recognize the target gene, unlike the two used in PCR, LAMP’s continuous amplification of DNA results in a process that is both highly specific and rapid.

Isothermal amplification methods for detection of foodborne pathogens 

In recent years, systems using isothermal amplification methods for detection of foodborne pathogens have recently started to become commercially available. In particular, the 3M Molecular Detection System utilizes the innovative combination of LAMP and bioluminescence detection technologies, resulting in a simpler, more robust DNA amplification and detection method and providing significant user benefits over older PCR technology. These two technologies make the system a cost effective, easy to use method with the molecular accuracy requested by customers. Corresponding pathogen-specific assays, or test kits, are also available for the detection of Listeria as well as Salmonella and E.coli O157 (including H7).

Listeria monocytogenes may not be a leading cause of foodborne illness as compared to other pathogens such as Salmonella or E. coli O157:H7, but its resilience and lethality make it a serious concern in the food industry. With robust sanitation practices and food testing, dairy processors can maintain safe environments and products.

John M. David is a global technical services engineer with 3M Food Safety, St. Paul, Minn.

Did you enjoy this article? Click here to subscribe to Dairy Foods Magazine.

You must login or register in order to post a comment.



Image Galleries

4 mouth-watering grilled cheese sandwiches you have to make in April, National Grilled Cheese Month

In recognition of National Grilled Cheese Month (April), Arla Dofino asked two food bloggers to re-imagine this comfort-food classic.

Heidi Larsen of and Maria Lichty of created four grilled cheese sandwich recipes that call for creamy Havarti, dill Havarti, smoked Gouda and Eureka! Organic Breads products.

Arla Foods, a cooperative owned by European dairy farmers, is the fifth largest dairy company in the world. The Arla Dofino brand of cheese includes Havarti, Gouda, Edam and Fontina, which are made by the Hollandtown Dairy in Kaukauna, Wis.

3/31/15 2:00 pm EST

Raising the bar with in-line mixing and blending technologies: high output with flexibility and low costs

On Demand In this webinar, you will be introduced to advanced in-line blending, dosing and mixing technologies that offer high flexible productions, reduced product losses, shorter batch times, uniform products, and reduced ingredient costs. As a result, Food Manufacturers can optimize their productions and increase their profitability.

Dairy Foods Magazine

april df cover

2015 April

We look inside Kroger's Denver plant; Also, see what trends are happening in yogurt.

Table Of Contents Subscribe


What is your favorite way to eat cheese?
View Results Poll Archive


Tharp & Young on Ice Cream: An Encyclopedic Guide to Ice Cream Science and Technology

An at once an all-inclusive guide to the meaning of hundreds of technical terms and ideas needed for ice cream manufacturing, as well as a practical introduction to the ingredients, freezing methods, flavoring, and packaging of ice cream, sherbet, sorbet, gelato, frozen yogurts, novelties and many other kinds of frozen desserts.

More Products

Clear Seas Research

Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Facebook logo 40px 2-12-13 Twitter logo 40px 2-12-13  YouTube logo 40px 2-12-13  LinkedIn logo 40px 2-12-13google plus

Dairy Foods Buyers Guide

cover df july 2013Resource for buyers in the dairy processing industry to find information on the leading suppliers and manufacturers.

Find Ingredients, Equipment, Distribution, R&D and More.

Start Your Search Today.