This week’s episode of the 2020 Food Safety Consortium Virtual Conference Series focuses on that pesky bug lurking in many food manufacturing and processing facilities: Listeria. The following are highlights for Thursday’s session:
Listeria monocytogenes: Advancing Food Safety in the Frozen Food Industry, with Sanjay Gummalla, American Frozen Foods Institute
Shifting the Approach to Sanitation Treatments in the Food & Beverage Industry: Microbial Biofilm Monitoring, with Manuel Anselmo, ALVIM Biofilm
A Look at Listeria Detection and Elimination, with Angela Anandappa, Ph.D., Alliance for Advanced Sanitation
TechTalk on The Importance of Targeting Listeria Where It Lives, presented by Sterilex
The event begins at 12 pm ET on Thursday, October 29. Haven’t registered? Follow this link to the 2020 Food Safety Consortium Virtual Conference Series, which provides access to 14 episodes of critical industry insights from leading subject matter experts! We look forward to your joining us virtually.
The food processing environment is ripe with hot spots where biofilm can hide. A rapid biological hygiene indicator in the form of a spray gel has been developed to provide companies with a visual indication of biofilm on a surface. Once the gel makes contact with biofilm it produces foam within two minutes. Manufactured by Sterilex, Indicon Gel does not require mixing and is appropriate for seek-and-destroy missions. It enables detection of microorganisms that include Listeria, E.coli and Salmonella on both large surfaces as well as niches that cannot be accessed by a swab.
It hides in the crevices. Once it gets onto equipment, it can linger for years. It’s biofilm, a formation of bacteria that adheres to surfaces and can be quite difficult to eradicate. A host of microorganisms, including Listeria and Salmonella, are linked to biofilm contamination. The following are insights gathered from Dominique Blackman, general manager at Realzyme, LLC and Jeff Mitchell, vice president of food safety at Chemstar during Food Safety Tech’s recent Listeria Detection & Control Workshop.
Biofilm Facts
Protected by multiple layers of polysaccharides
Acts as binding site for antimicrobials as well as a diffusion site, protecting bacteria within
Mechanisms of dispersal
Active: Releases cells based on environmental changes
Passive: Occurs as a result of shear or agitation (i.e., when doing deep cleans or moving equipment)
Hot spots
Transfer points in facility
Product contact points on equipment
Drains
Seams in walls/floor-wall junctures
Door seals
Cart wheels
Overhead vents and pipes
Causes a variety of problems within food manufacturing facilities, including:
Product contamination = Economic loss (i.e., as a result of recalls)
Reduced product shelf life (i.e., result of recurring contamination)
Reduced productivity, especially when equipment isn’t cleaned properly
Bacterial resistance to disinfection
Surface corrosion (the longer biofilm is in one place, the more time it has to damage equipment)
Successful removal requires complete penetration of extracellular polymeric substance without inactivating any sanitizer
More effective environmental monitoring and improved sanitation practices, along with databases such as PulseNet, are helping the industry find Listeria contamination. However, once detected, many processing facilities have difficulty removing the bacteria.
Next month Food Safety Tech is holding a Listeria Detection & Control Workshop to educate food industry professionals about how to integrate prevention and mitigation procedures into existing sanitation, operation and testing programs. The two-day workshop, which takes place May 31 – June 1 in St. Paul, MN, will cover the basics of controlling Listeria, along with the following topics:
Detecting and penetrating biofilm
How to build an effective environmental testing program
Producing reliable testing to detect and control Listeria
Sanitation departmental role in prevention, control and mitigation
Building a master sanitation schedule
Innovative Listeria mitigation programs
Gaps in proactive food safety programs
Hygienic equipment design
Industry speakers include:
John Besser, Ph.D., deputy chief, enteric disease laboratory branch, CDC
Gina (Nicholson) Kramer, Savour Food Safety International
Dominique Blackman, Realzyme
Janet Buffer, The Kroger Company
Ken Davenport, Ph.D., 3M Food Safety
Bert de Vegt, Micreos Food Safety
Joellen Feirtag, Ph.D., University of Minnesota
Melinda Hayman, Ph.D., GMA
Sanja Illic, Ph.D., Ohio State University
Paul Lorcheim, ClorDiSys Solutions
Douglas Marshal, Ph.D., Eurofins Scientific
Jeff Mitchell, Chemstar
Megan Murn, Microbiologics
Robin Peterson, Micreos
Errol Raghubeer, Ph.D., Avure Technologies
The event takes place at the 3M Innovation Center in St. Paul, Minnesota. Workshop hours are Tuesday, May 31 from 11:00 am–6:00 pm and Wednesday, June 1 from 8:30 am–5:00 pm. For more information, visit the Listeria Detection & Control Workshop event website.
Recent recalls and outbreaks associated with Listeria coupled with FDA’s finalization of the FSMA preventive controls rule have heightened the industry’s need to focus on environmental testing programs. The need for a preventive control program with higher resolution is especially highlighted by the government’s increasing use of whole genome sequencing data to more rapidly link human illness to food processing establishments. I work with many customers who simply do not recognize all of the factors that influence their ability to detect Listeria in environmental samples. For many, an environmental sample is collected, shipped to a third-party lab, results are received within two to four days, and few questions asked. Most companies have not invested the time and resources needed to truly understand how each component of an environmental sample impacts their ability to detect Listeria. So what factors should be considered to maximize Listeria detection in the plant environment?
Learn innovative ways to mitigate the threat of Listeria at the Listeria Detection & Control Workshop | May 31–June 1, 2016 | St. Paul, MN | LEARN MOREListeria is a True Survivor
Listeria is inherently a hearty organism that can withstand highly adverse conditions in the plant environment. It is able to survive and grow across a wide range of temperatures, including refrigeration, and it is more tolerant to heat than Salmonella and E. coli. Additionally, the organism survives across a wide pH range, including extended periods in highly acidic conditions, and can survive food processing and preservation with up to 25.5% salt. These traits may result in highly injured Listeria being collected in environmental samples, and requires optimization of the sample collection and analysis process in order for detection and culture confirmation to occur.
Sanitation Programs May Not Destroy Listeria
Sanitation practices are intended to destroy Listeria in the plant environment, but not all sanitizers will be 100% effective. In some cases, sanitizers may not fully kill Listeria, leaving highly injured Listeria that may require an extended lag phase in order for growth and detection during testing. Sub-lethally injured Listeria remains a food safety concern, as the bacteria maintain the ability to recover and flourish in a nutritive environment. Additionally, Listeria readily forms biofilms in the plant environment, which many traditional sanitizers do not effectively remove. Biofilms in the plant environment may maintain low levels of Listeria that may be challenging to detect without the use of a sensitive detection method.
Sample Collection: Choose the Right Tool for the Job
The neutralizing and nutritive capacity of the collection media used with the collection device can have a significant impact on the ability to resuscitate, detect and culture stressed Listeria. When selecting a collection media, it is important to ensure that the media will effectively neutralize the sanitizers used in the plant environment. For instance, peroxyacetic acid and quaterinary ammonia-based sanitizers will not be neutralized well by commonly used collection media such as Neutralizing Buffer or Letheen Broth. Neutralization of the sanitizer in environmental samples is important in order for resuscitation and growth of any Listeria present within the sample. Additionally, use of a collection media that contains nutrients to begin the resuscitation process for Listeria immediately upon collection is also important for detection and culture confirmation of Listeria in samples. Collection media such as Neutralizing Buffer contains monopatassium phosphate, sodium thiosulfate, and aryl sulfonate complex intended only to neutralize sanitizers. Conversely, D/E Broth and HiCap Broth have components to nourish Listeria and facilitate resuscitation in addition to neutralizing sanitizers.
Enrichment Media Determines Recovery & Growth
Enrichment media plays a major role in the speed of recovery and growth of Listeria in environmental samples. Medias that facilitate faster recovery of injured Listeria allow for shortened lag phases facilitating more rapid growth. Enrichment media that facilitate faster recovery and growth allow Listeria to reach the limit of detection for screening tools more quickly. When paired with a highly sensitive method, enrichment media, which foster greater Listeria growth and recovery, can allow for significant reductions in time to results for screening methods. Additionally, faster recovery and growth of Listeria due to enrichment media can increase the likelihood of culturally confirming Listeria found at low levels pre-enrichment.
Not All Detection Methods are the Same
The ability of a detection method to find Listeria in an environmental sample is impacted by two factors: 1) method sensitivity and 2) method robustness in the presence of sanitizers. The more sensitive a rapid test method, the greater the chance of finding low levels of Listeria in an environmental sample. Low levels of Listeria in environmental samples are likely due to the injured state of Listeria in the plant environment post sanitization. Immuno-based rapid methods have a sensitivity of 105–106, DNA-based methods have a sensitivity of 104–105 and RNA based methods have a sensitivity of 102–103. Using an RNA-based method offers 1 to 2 logs greater sensitivity and greatly increases the chance of finding low-level Listeria.1 This can be particularly true when sampling conditions such as collection media or enrichment media are less than optimal for the neutralization of sanitizers and growth and recovery of Listeria.
Another important factor that influences a test method’s ability to detect Listeria in an environmental sample is the method’s ability to amplify and detect the organism in the presence of sanitizers. Most molecular-based methods do not include a sample clean up step resulting in sanitizer being present during the amplification step. For some methods, sanitizers may inhibit amplification, resulting in indeterminate or false negative results.
Confirmation Requires Optimization of the Sampling Process
The ability to culturally confirm a Listeria sample that screens positive is influenced by the entire environmental sampling process. In order to culture confirm samples with highly injured, low-level Listeria, it is necessary to optimize the sample collection media, enrichment media, and confirmation process to provide the greatest likelihood of culture recovery. If Listeria is not adequately resuscitated and able to achieve sufficient growth, the level of Listeria present in the sample post-enrichment may be below the limit of detection for culture. The likelihood of culture confirmation can be increased by incorporating steps such as a secondary enrichment or concentration via IMS capture. Culture confirmation for samples that screen positive on a rapid method can be especially challenging if a highly sensitive test method is used for screening that may detect Listeria at lower levels than culture. Thus, optimizing the environmental sample program is especially important if confirmation of screening results for highly sensitive methods is desired.
Method Sensitivity and Increased Positivity
Employing a highly sensitive screening tool for environmental samples provides a better lens to view risk within the food safety processing environment. Many companies fear that a more sensitive method will result in significant increases in positivity and cost for increased sanitation. In working with customers who have moved from immune-based methods to a highly sensitivity molecular method, I’ve observed an initial increase in positivity followed by a leveling off of low-level positivity after enhanced interventions are taken in the plant. Companies that proactively seek out and destroy Listeria in their plants are then able to maintain low level rates of positivity with routine cleaning measures, while also maintaining the confidence that they are using the best tool available for Listeria monitoring.
Understand Your Risk & Establish a Culture of Food Safety
It is important for food safety professionals to fully consider the hidden risks that may exist in their plant environment due to the environmental sample process masking the true presence of Listeria. Each component of the environmental monitoring process, sanitizer, collection media, enrichment media, detection method and culture process plays an important role in a company’s ability to be able to detect and culture confirm Listeria in the plant environment. Optimizing each step within the environmental sample process allows a company to be proactive instead of reactive. This approach creates a company culture of food safety that can seek out, detect and destroy Listeria in the plant environment, can significantly mitigate risk. The good news is that by incorporating the right food safety culture and making data-driven choices, today’s manufacturer can achieve both short-term dividends of risk reduction as well as a long-term elevation of control of its process.
Most recently we have seen an increase in foodborne illness outbreaks from Listeria to Salmonella to Norovirus to E.coli, many of which are a result of post-lethal contamination of processed foods. This is often a direct result of a gap in the sanitation programs that were in place at the processing facilities. Every facility should conduct a sanitation gap analysis on an annual basis. In order to receive unbiased feedback, this activity is best performed by a third party that is not a chemical provider.
Join Gina Kramer at the Listeria Detection & Control Workshop, May 31–June 1 in St. Paul, MN | LEARN MOREDeveloping and implementing a sound environmental hygiene program at a food processing facility is essential to its success in producing safe food for consumer consumption. There are fundamental basics of sanitation that every plant must follow in developing a strong program. The fundamental basics include: Developing sanitation standard operating procedures (SSOPs) for; Floors and drains, walls, ceilings, equipment and utensils, and employees. SSOPs must also contain perimeter control, foot traffic control into food preparation areas, zoning, and environmental sampling procedures.
VIDEO: Jeff Mitchell and Gina Kramer discuss the increase in Listeria recalls. | WATCH NOW
When developing SSOPs, using the proper risk reduction formula will lead to sanitation success. To determine the best risk reduction formula, I sought the advice of sanitation expert, Jeff Mitchell, vice president of food safety at Chemstar. Before working for Chemstar, Mitchell was the Command Food Safety Officer for the United States Department of Defense (DOD). Serving more than 20 years for the DOD has given him the opportunity to visit thousands of processing facilities all over the world, seeing the best and the worst, and assisting in finding the root cause of contamination issues and negative environmental sampling results. In this article, I share Mitchell’s risk reduction formula for sanitation success and how to use the formula to build a solid and successful sanitation program.
Foundational Science
“An understanding of the difference between transient and persistent (or resident) pathogens is a key part in the foundational science of sanitation solutions,” explained Mitchell as we discussed the details of the risk reduction formula. Transient pathogens are those that are introduced to the processing facility from the external environment. Entrance occurs from deliveries on transportation vehicles and pallets, food, and non-food products and its packaging, employees and visitors, pests and rodents, along with leaks in the roof or improper cleaning of drains, which are known reservoirs.
“Persistent pathogens are those pathogens that establish residency within the processing facility. Most bacteria will aggregate within a biofilm, allowing them to live in communities. A biofilm is a survival mode for the bacteria; it protects it from sanitizer penetration. The biofilm layers actually masks it from sampling detection. You could swab a surface or an area and not get a positive pathogen test result, because the biofilm is masking it,” Mitchell stated. He continued to explain that most contamination risks are likely from established populations. Four things need to exist for resident populations to form: Pathogen introduction, water, trace organics and niche area for attachment and growth. Food processing facilities should be most concerned about these populations, as they’re being traced to many recent outbreaks and recalls.
In his experience, Mitchell shared that sanitation efforts should focus on areas within the processing facility where moisture and nutrients are collected; both are needed for biofilm formation. Disruption of these niche areas containing biofilm can result in direct (food contact) and indirect (non-food contact) contamination if the biofilm is not completely penetrated or removed. This can occur through active and passive dispersal of pathogens. Active dispersal refers to mechanisms that are initiated by the bacteria themselves where they naturally eject from the biofilm and land on other surfaces. Passive dispersal refers to biofilm cell detachment that is mediated by external forces that shear the biofilm, causing it to move and further spread. This can be caused through fluid shear, abrasion and/or vibration due to power washing, equipment vibration, or deep cleaning/scrubbing that does not penetrate and remove all the aggregate layers of biofilm. In other words, the biofilm and pathogens are just smeared around the facility like cleaning a mirror with a greasy wiping cloth.
Chemistry and Application
The cleaning matrix must be considered to properly remove soils that house both transient and persistent pathogens. This is done by combining proper cleaning and sanitizing agent concentration (PPM), adequate exposure time, proper temperature and mechanical action (agitation) or good old elbow grease. If there is a decrease in one area of the matrix, then an increase in the other areas needs to be made as an accommodation to the cleaning process. My years working in industry have taught me that the most expensive quadrant of the cleaning matrix is agitation, because it requires manual labor. Reduction of labor is one of the first ways companies build in efficiencies to increase profit margins. That means a solution must be built that focuses on temperature, concentration and proper contact time to produce the sanitation results necessary to prevent persistent pathogens from establishing residency within processing facilities.
Temperature should be regulated by the type of soils that need to be removed. High fat soils need a higher temperature of about 140⁰ F. However, when removing high protein soils, the temperature needs to be reduced so that the protein is not baked onto the surface. Baked proteins that are not removed become nutrients for bacteria to aggregate and reside. High temperature is does not work in every food processing plant, Jeff explained.
Proper balance of detergent and sanitizer is necessary to remove and destroy both transient and persistent pathogens. The detergent needs to be the right formulation and contact time to break down soils and biofilms with application of the right concentration and contact time of sanitizer to kill the exposed pathogens. Without the right balance in place it can create the perfect storm for spread and contamination within the processing facility.
Validation
Do your homework. Research is the most valuable tool when validating the effectiveness of a cleaning process. Private research is good but not the only form of validation on which to base a business decision. I have found that peer reviewed published research is best to use in validating all quadrants of the cleaning matrix. Academic research based on sound science that has practical application results is worth the investment to make sound business decisions.
Many products have been developed to penetrate and destroy the biofilm layers that bacteria aggregate. Again, do your homework. Choose a product that also provides a pathogen kill once the biofilm has been penetrated. I cannot stress enough to make sure that the SSOPs follow the manufacturer’s validated processes and the sanitation team follows the SSOPs’ directions.
Solution
Applying the desired solution requires dividing the processing facility into zones to designate specific sanitation requirements. This will assist in the development of specific SSOPs that apply the right solution in the right zone throughout the site.
Mitchell also gave great advice about cleaning tools and cleaning chemical basics. He explained that a facility should color code the cleaning tools according to zone and only use them in the designated zone area. This prevents cross contamination from occurring, because cleaning tools can be vehicles of contamination transfer. Utilize foam detergents and foam sanitizers as they are more forgiving and increase contact time, and sanitation crew can see where they have applied the chemicals. Use the Ross-Miles foam test for stability: Foam should last more than three minutes before breaking and turning into a liquid solution that runs down the drain, costing a site money and opening up the potential for introducing pathogens into production rooms.
Mitchell advised the development of sanitation procedures that focus on daily thorough cleaning of everything from the knees down in Zones 1-3. “You want to knock everything down and keep it down. The objective is to keep bacterial creep from occurring,” he said. “Creep is where bacteria are moved by processes like water spray, splash and aerosolization, causing the bacteria to move from one area (it usually develops on the floor) to then move up walls and the legs of equipment, etc.— eventually causing contamination of food during food production and packaging.” Obviously, all food contact surfaces in Zone 1 need to have specialized SSOPs according to the equipment, food processing shifts per day, and type of foods that are being processed.
Mitchell stressed that perimeter and foot traffic control entry programs should incorporate a good foam sanitizer that stands up to the Ross-Miles test with optimal duration of five minutes. The distribution of the foam should cover a large enough area that the employees’ foot path and equipment must travel through the foam to achieve contact to control transient pathogen entrance into Zones 1–3. Concentration levels of these areas should be at least double what the food contact area strength is for effectiveness of log kill needed for control.
Environmental monitoring procedures should follow the zoning process set up for sanitation. “Swabbing for Adenosine Triphosphate (ATP) and/or Aerobic plate count (APC) are tools that can be used to help identify biofilm locations. One thing to note is that the bacteria located under the biofilm are in a modified dormant state requiring less energy and making less ATP available for detection. With that said, ATP and APC swabbing are still both viable tools to use in sanitation verification,” said Mitchell. If you only test for general risk pathogens in your facility you may receive false negatives due to biofilm masking the pathogen from showing up as a positive in environmental testing. Utilizing both general pathogen, ATP and APC in concert, is the best combination in a facility’s environmental monitoring program. The goal is to seek and find then destroy and verify.
I recently discovered a great biofilm visual detection test from Realzyme that is wonderful to use to verify whether the sanitation system in place is working. It can also differentiate between protein build-up and biofilm formation. In my professional opinion, this visual detection test is essential to incorporate in a robust environmental testing system.
Safe Food: The End Product
Our responsibility as food safety/quality professionals is to provide the safest, most delicious food for our customers to enjoy. To ensure safe food in our end product, we need to develop a robust sanitation and environmental testing program that follows the risk reduction formula (Foundational Science + Chemistry & Application + Validation = Solution) and conduct an annual sanitation gap analysis by a third-party expert for continuous improvements.
Apply these steps to protect your food, protect your brand and protect your customers so that they Savor Safe Food in every bite!
“When a flower doesn’t bloom you fix the environment in which it grows, not the flower.” A quote, by Alexander Den Heijer, trainer, speaker, purposologist, that rings true in food safety. When there is a contamination issue in food processing, one must fix the environment in which food is being processed. Safe food is a product of a clean environment.
We have better environmental sampling programs in our food manufacturing plants and processing facilities, and we have sanitation standard operating procedures, so why are we seeing a prevalence of Listeria, and in rising numbers? I recently sat down with Jeff Mitchell, vice president of food safety at Chemstar, about the recent increase in Listeria outbreaks and how you can rid your facility of the dangerous pathogen.
We’re seeing Listeria—in product recalls and outbreaks—over the last couple of years, and in multiple numbers. Why do you think this is happening?
My interview with Jeff Mitchell about the increase in Listeria recalls. Watch the video
Jeff Mitchell: The distribution of Listeria in the environment has not changed, and the processes that we use for processing food really haven’t changed. What’s changed is the way that we collect data. We have PulseNet now, which gathers information. If someone goes to a medical treatment facility with a foodborne illness, they’re going to investigate that and they’re going to get the whole genome sequencing on the pathogen.
There’s a difference between understanding what transient Listeria is and resident Listeria. I think there are a lot of sanitation efforts being put forth to eliminate the resident populations—those are the populations we’re most concerned about, and they’re the ones that are being related back to a lot of these recalls.
If I have resident Listeria in my facility, why can’t I find it?
Food Safety Tech is organizing a Listeria Detection & Control Workshop, May 31 – June 1, 2016 in St. Paul, MN. LEARN MOREMitchell: Resident populations of Listeria are found in a biofilm—most bacteria aggregate within a biofilm. A biofilm is a survival mode for the bacteria; it protects it from sanitizer penetration. That layer actually masks it from sampling. You could swab a surface or an area and not pick it up, because the biofilm is masking it.
Jeff goes on to discuss the type of sanitation program that companies should have in place to get rid of resident Listeria. You can learn about the steps you need to take in my video interview.
Why has the food industry been seeing more Listeria outbreaks in recent years? What is the reason behind it? According to Jeff Mitchell, vice president of food safety at Chemstar, the prevalence in Listeria-related recalls may have more to do with the fact that industry is collecting more meaningful data. During a Q&A with Gina Kramer, founder and executive director of Savour Food Safety International, Inc., Mitchell discusses the methods through which industry is collecting data and how food companies should be using a sanitation program to rid facilities of resident Listeria at the 2015 Food Safety Consortium.
By Gina R. Nicholson-Kramer, Jeff Mitchell No Comments
Listeria: It has been in the news and in our food throughout the past year. It has cost companies millions of dollars in recalls, shutdowns and mitigation; it has cost the government thousands of dollars in outbreak investigation, inspection and follow-up; and it has cost millions of dollars in medical bills for victims and for some, it has cost their lives.
I have asked Jeff Mitchell, vice president of food safety at Chemstar, to share his knowledge about Listeria mitigation and control, and to talk about the research that supports the innovative program that Chemstar uses with its customers.
Listeria Mitigation & Control Program
By Jeff Mitchell
Jeff Mitchell, Vice President of Food Safety, Chemstar
Thus far this year there have been several recalls of ready-to-eat (RTE) foods due to contamination with Listeria monocytogenes. Efforts to prevent contamination of food products with Listeria monocytogenes must be conducted at all levels of production. This is a difficult task given the fact that the bacteria is so widespread in the environment. Focusing efforts in your process where contamination risk is of greatest concern to the consumer is important. There is solid evidence that commercially prepared foods that have been contaminated with Listeria monocytogenes has occurred after the food product has been subjected to an initial lethality treatment. The product may be exposed in this area as a result of slicing, peeling, packing, re-bagging, cooling, or other procedures that may expose the product to potential contamination.
Listeria monocytogenes survives extremely well in food processing and retail food preparation environments. It may be introduced into your facility through a variety of routes, including:
Raw materials
Employees’ shoes or clothes
Equipment (boxes, crates, carts)
Controlling traffic flow into critical areas of the process can help reduce the chances of introducing and spreading the organism.
Once Listeria is introduced into the nonsterile environment, retail and factory conditions that promote its growth increase the risk of post-processing contamination. Several factors, including moisture, nutrients, temperature, competitive microflora and pH, affect the growth of Listeria in the food preparation and processing environment. Moisture is the most crucial factor, as it is essential for microbial growth and is the most easily controlled of the factors.
Listeria tends to form a biofilm to enhance its survival when resident populations become established in the food prep/processing environment. The resident populations that are referred to as “persistent” are not easily eliminated by general cleaning and sanitizing procedures. Biofilm penetration is necessary for removal and inactivation of Listeria. The correct blend of chemical, contact time and agitation will aid in the removal. This combination dissolves the biofilm and the organic material to which it adheres, allowing the sanitizer to inactivate the released, sensitive cells.
To learn more about Listeria from Gina and Jeff, check out their archived webinar with Food Safety Tech, Preventing Listeria Contamination: A Practical Guide to Food Safety ControlsBiofilm removal is important, because persistent L. monocytogenes can be dispersed from a biofilm into the environment and onto food processing equipment, and non-food contact and food-contact surfaces. Passive dispersal of Listeria can occur by aerosolization from high-pressure hoses or brushing; once aerosolized, Listeria can contaminate other growth niches in the food handling/processing area, eventually contaminating food contact surfaces and food. Another form of passive dispersal is the movement of processing equipment. If a biofilm is present, cells can be released by the movement or vibration of the equipment.
Inactivation of L. monocytogenes in biofilms is an important part of a Listeria control program. Understanding this face prompted our team to perform research with the University of Georgia using a mixed culture biofilm formed by Pseudomonas putida and L. monocytogenes to evaluate the ability of Chemstar’s foaming sanitizer to inactivate L. monocytogenes present in biofilms under realistic use conditions. The results revealed that it provides for a greater than four-log reduction.1
Identifying Listeria in the environment and eliminating the resident populations can reduce the risk of secondary contamination. Once these procedures are established, employee training and environmental monitoring are vital. An effective Listeria control program requires that employees understand their role in mitigating the spread of Listeria, and management must relay those expectations. Control strategies are not likely to be effective if employees won’t cooperate, or don’t understand what they are expected to do, or why it is important, and that expected procedures or behavior will be monitored.
Reference
Frank, J. and Mitchell, J. (December 3, 2010). Evaluation of Chemstar foaming sanitizer for inactivating Listeria monocytogene in floor drain biofilms.
Join us for the Listeria Mitigation and Control Workshop at the Food Safety Consortium in Schaumburg, IL on November 17, 2015. Learn about the Five Key Elements in building an effective Listeria Control Program:
Specific Sanitation Controls for Listeria
Training of Personnel (they need to understand their role in the program)
Traffic Control
Targeted Environmental Monitoring and Testing
Control Water Introduced into the Process Environment
The workshop will be a hands-on approach to learning about Listeria and practical solutions to take back and implement into your company’s sanitation program.
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