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Biofilm and food safety: What is important to know?

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Dr. Bassam A. Annous, Eastern Regional Research Center, USDA–ARS–NEA, and Dr. Ruth Eden, BioExpert.

Part 1: What are Biofilms?

In nature, most bacteria do not exist as suspended (planktonic-free floating) cells. Bacteria live in a group (mass of bacterial cells) attached to each other and to surfaces, in a biofilm form.
A biofilm is as a complex community of microorganisms, embedded in self-created extracellular polymeric substances (EPS). Therefore, the biofilm is a microbial population adherent to each other and to surfaces or interfaces enclosed in the matrix. In this complex biofilm network of EPS, the bacterial cells perform less as individual cells and more as a collective living system, frequently creating channels to deliver nutrients and water to the cells located inside the biofilm.
Bacteria create biofilm as a protection mechanism, for better survival in the environment. Cells in a biofilm are more resistant to cleaning and disinfection processes in the food industry. The bacteria in the biofilm attaches so firmly to the equipment’s surface that it becomes resistant to conventional sanitation procedures used by the food industry.
Various techniques such as molecular methods, chemical methods, and physical methods have been used to better understand the complex mechanism of biofilm formation, and to get an insight into how to create a process that will eliminate the biofilm formation and/or inactivate cells within the biofilm.
Moisture and nutrients from food (organic and inorganic material) are commonly found on production lines. These two elements bond together to create a conditioning layer. This layer allows for the initial attachment of the bacterial cells to the surface of the layer and the secretion of EPS. The production of ESP enhances the biofilm attachment to the food contact surfaces and protects the cells within the biofilm from the external stresses such as sanitizing agents.

How is Biofilm Formed?

The formation of biofilm can be described as a stepwise process, as shown in Figure 1, consisting of:
  1. Initial reversible attachment of the planktonic (free-floating) bacteria cell to the surface
  2. Irreversible attachment by the production of EPS
  3. Bacteria multiplication and development of biofilm structure
  4. Development of a microcolony covered by mature biofilm, stabilizing the microcolony from environmental stress
  5. Dispersion of cells from the biofilm into the surrounding, and the return of cells to their planktonic form.
 
Figure 1: Formation of biofilm (adapted from Wikimedia , and Firstenberg-Eden et al )
Organisms in a biofilm act less as individual cells and more as a combined living system and are significantly more resistant to environmental stresses such as antibiotics, sanitizers, chemical stress (pH, oxygen) and biocides than their planktonic cells. This increase in resistance to external stresses, as well as a shield against desiccation, is probably due to the presence of the EPS material.
Quorum sensing (cell to cell signaling) has been shown to play a role in biofilm formation, allowing bacteria to display a unified response that benefits the whole population. Research shows that transfer of antibiotic resistance gene is common in the biofilm environment. This transfer happens readily through conjugation or transformation.
Quorum sensing also enhances the ability of bacterial cells within the biofilm to access nutrients and increases their defense mechanism against competing bacteria and environmental stresses.
A recent publication in Cell showed that bacteria residing within biofilm communities could coordinate their behavior through cell-to-cell electrical signaling. Combining experimental data and mathematical modeling point to an extracellular potassium produced in the biofilm as a mechanism of changing the membrane potential of remote cells, thus, directing their motility.
Therefore, cells embedded within the biofilm can not only influence their behavior but influence the behavior of far-away cells through electrical signaling.  A genetic mechanism appears to allow electrically mediated attraction between bacterial species

Why are Biofilms important to Food Safety?

Continual low-level contamination can be caused by biofilm, releasing bacteria, including pathogens and therefore, causing a food safety concern. Bacteria residing in biofilms are more resistant to antimicrobial agents and cleaning agents. Biofilms on processing equipment can reduce the lethality of the process.
Attached cell increased resistance to cleaning chemical because of the protection provided by the EPS layer. The decreased effectiveness of chemicals might also be as a result of cells being in a compact format reducing exposed surfaces that the chemical can make contact with the bacteria.
Product contamination can occur as bacteria detach from the microcolony periodically and can contaminate the processed foods and the lines.  Pathogenic bacteria such as, Listeria, Salmonella, E. coli, or Pseudomonas, can form a multi-species biofilm, which is more stable and resistant to sanitizing agents.
 
Many outbreaks of foodborne disease are associated with biofilm. Research shows that biofilm has become a problem in food industries such as dairy, fish processing, poultry, meat, and Ready-To-Eat foods, because of the residing organisms increased resistance to external stresses.

Biofilm formation on food surfaces

Fruit and vegetable

Research has shown that bacteria can attach, colonize on the surfaces of plants, eventually forming biofilms. The ability of sanitizers to inactivate the bacterial cells in the biofilm is significantly reduced
Disinfection steps by a diverse group of chemicals (e.g., chlorine, peroxide, surfactants, organic acids, etc.), UV, and irradiation were tested without successfully eliminating pathogens in the biofilms formed on fresh produce (without significantly affecting the product quality).  Pathogens that are incorporated into mixed-species biofilms make them less susceptible to antimicrobial treatments as well as increase their tolerance to other stresses such as desiccation and UV.
Biofilms on plant surfaces are composed of a wide variety of bacterial species.  The population dynamics of biofilms vary greatly corresponding to environmental conditions such as temperature, relative humidity, and the availability of nutrients.
Biofilm formation on plant surfaces is probably a survival mechanism for bacteria to endure harsh environment, including desiccation, UV exposure, and temperature fluctuations.
Research data (Bassam A. Annous 2005 ) shows Salmonella produces fimbriae and cellulose, starting biofilm formation, which helps the organism attach and colonize on melon and cantaloupe surfaces. Once attached to the fruit Salmonella cells survive better, and are less susceptible to the harsh sanitizing environment. The organism becomes difficult to remove from the cantaloupe surfaces due to attachment to inaccessible sites and biofilm formation on the cantaloupe rind surface, thus avoiding contact with the sanitizing solution.
After that, the surviving cells can be transferred from the surface of the fruit into the internal tissue of the fruit during processing, presenting a major obstacle for ensuring the microbiological safety of fresh-cut cantaloupe.
The produce most frequently associated with outbreaks include cantaloupe melons, apples (unpasteurized juice or cider), and leafy greens.

Meat

There are meat surfaces to which bacteria attach readily and other meat surfaces to which they attach much slower. The smooth chicken breast muscle (fascia) was the best surface for attachment of all bacteria examined. A linear relation between the concentration of bacteria attached to the surface and time during the attachment process was observed. On some surfaces, this linearity continued for a long time [teats of a cow, chicken breast with fascia, chicken skin]. Bacterial strain also impacts the attachment kinetics.
The bacteria are easily removed in the water film stage. With time, these bacteria could attach to the meat and become difficult to remove due to EPS formation. Brown et.al showed the attachment and biofilm formation by Campylobacter jejuni to extruded chicken meat. They demonstrated that chicken juice contributes to C. jejuni biofilm formation by covering and conditioning inert surfaces and is a source of nutrients. The organism preferentially attached to chicken juice particulates, increasing the attachment rate.
 
Escherichia coli O157:H7 from cattle had the ability to produce biofilm on food contact surfaces such as stainless steel. The attached organisms in the biofilm were able to transfer onto a variety of products such as raw meat, raw poultry, ready-to-eat deli meats, and produce products.
Strains isolated from cattle, retail chicken, and retail beef were able to form strong biofilms in addition to curli fimbriae and EPS production.
Spoilage and/or Pathogenic bacteria can attach to production food contact surfaces, and eventually form a biofilm. The biofilm formation is a major challenge to the meat industry due to the potential of cross-contamination of the meat, causing short-shelf life and/or spread of diseases.

Equipment

Both Gram negative and Gram positive bacteria present on food processing equipment can colonize on stainless steel.  Gram-negative bacteria produced much greater biofilms on stainless steel than Gram positives.
The ability of Listeria monocytogenes to develop biofilms and survive on different types of materials was studied by Wong 2002. The materials studied included two types of stainless steel (304 and 316L), two types of rubber (Buna-N and silicone), and three materials used in conveyor systems (Polyester 3000 and TURE-2 used as belting material, and Delrin, a hard plastic, used in rollers for conveyor belts).
Biofilm formation was best supported by the plastic material Delrin, followed by stainless steel type 304. Food grade silicone rubber and stainless steel type 316L surfaces were the most resistant to biofilm development. L. monocytogenes was capable of forming a biofilm at 10°C, in low nutrient medium on all surfaces tested. The 5-day biofilm cells were more resistant to cleaning and sanitizers as compared to the 2-day biofilms.
The persistence of bacterial cells within a biofilm in the whole food industries including cheeses, dairy products, raw foods, and ready to eat produce continue to contribute to the short shelf-life and/or human pathogenic foodborne outbreak. ESP Material produced by the bacterial cells in biofilms and the complexity of processing equipment makes it difficult to remove and/or inactivate these bacterial cells on food processing surfaces. Therefore, biofilm control relies on the implementation of effective cleaning and sanitizing procedures. Also, the design of processing equipment and the food processing environment that reduces and/or eliminates the accumulation of bacterial and that allows easy, and thorough soil removal can be a significant issue in controlling biofilm formation.
Comming soon our second chapter about Part 2: What are the best control strategies?
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Consumption of Unpasteurized Cow’s Milk and Cheese and its Impact on Outbreaks and Diseases

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Introduction

Despite of everything we learned about the danger of raw milk and its products, the sales of raw or unpasteurized milk and milk products are still legal in at least 30 states in the United States.  Raw milk and milk products from cows, goats, and sheep continue to be a source of bacterial infections attributable to a number of virulent pathogens, including Listeria monocytogenes, Campylobacter jejuni, Salmonella species, Brucella species, and Escherichia coli O157.
A report published in Emerging Infectious Diseases, Volume 23, Number 6—June 2017  by Solenne Costard , et,al. stated that the growing popularity of unpasteurized milk in the United States raised public health concerns. The authors estimated the impact of outbreak-related illnesses and hospitalizations caused by the consumption of cow’s milk and cheese contaminated with Shiga toxin–producing Escherichia coliSalmonella spp., Listeria monocytogenes, and Campylobacter spp. by using a model relying on publicly available outbreak data.
The trend towards increased availability of unpasteurized dairy products raises public health concerns, especially since raw milk consumers include children.

Why Raw Milk

Consumers are increasingly demanding more natural and organic foods (i.e., minimally processed foods). Following a similar trend the popularity of unpasteurized milk in the U.S. has been growing as well. Advocates of raw milk claim that it is rich in beneficial bacteria, natural vitamins and food enzymes. Many small-scale and local dairy farmers also strongly support the raw milk movement, as do many natural health advocates. 
Raw milk enthusiasts claim that the products taste better, produce fewer allergic reactions and can cure illnesses — claims that are all anecdotal and unproven. Consumers also point out that raw milk tends originate from family farms rather than “factory farms”.
Efforts to limit the sale of raw milk products have met with opposition from those who are advocates of the alleged health benefits of consuming raw milk products, which contain natural or unprocessed factors not inactivated by pasteurization.
However, the increased consumption of raw milk and its products is raising public health concerns. This is because, in contrast to some perceptions, natural food products are not necessarily safer than conventional ones, as evidenced by higher rates of foodborne illnesses associated with unpasteurized dairy products.
The CDC believes that “There are no health benefits from drinking raw milk that cannot be obtained from drinking pasteurized milk that is free of disease-causing bacteria. The process of pasteurization of milk has never been found to be the cause of chronic diseases, allergies, or developmental or behavioral problems.” and the CDC condemns its consumption.

The Study

In the study a total of 87 outbreaks causing 750 laboratory-confirmed illnesses and 215 hospitalizations were considered. The incidence rates of STEC, Salmonella spp., and Campylobacter spp. illnesses and hospitalizations per 1 billion servings were higher for unpasteurized dairy product consumers than for pasteurized dairy product consumers. Illnesses and hospitalizations caused by L. monocytogenes infections which were more often attributed to the consumption of pasteurized cheese than unpasteurized cheese.
The authors calculated that if the percentage of unpasteurized milk consumers in the United States were to increase to 3.8% and unpasteurized cheese consumers to 1.9% (i.e., an increase of 20%), the number of illnesses per year would increase by an average of 19% and the number of hospitalizations by 21%.
If the percentages of unpasteurized milk and cheese consumers were to double, the number of illnesses would increase by an average of 96%, and the number of hospitalizations would increase by 104%, resulting in additional 733 illnesses/year and 22 hospitalizations/year, which correspond to a total of 1,493 illnesses/year mostly caused by Salmonella spp. and Campylobacter spp.
In this study bulk milk tanks on US raw milk farms has been found to contain STEC in 2.5% of the cases, Salmonella spp. in 4.6%,  L. monocytogenes in 2.5%, and Campylobacter spp. in 4.7% of the cases.
 

The Take-Home Message

In the US outbreaks associated with dairy consumption cause on average 760 illnesses/year and 22 hospitalization/year, caused mostly by Salmonella spp., and Campylobacter spp. While unpasteurized milk is consumed by only 3.2% of the population, and cheeses from unpasteurized milk by only 1.6% of the population, they caused 96% of the illnesses caused by dairy products.  This result means that unpasteurized dairy products cause 840 times more illnesses and 45 times more hospitalizations than pasteurized dairy products.
Despite a decrease in dairy consumption in the United States, recent studies suggest that over the past 15 years the number of outbreaks associated with unpasteurized dairy products has increased.
The authors state that as consumption of unpasteurized dairy products grows, illnesses will increase steadily; a doubling in the consumption of unpasteurized milk or cheese could increase outbreak-related illnesses by 96%.
Consequently, those who consume raw milk are taking chances with their health since consuming raw milk increases the chances of getting an outbreak-related illness by more than 800 times.
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A New Method for the Detection of Salmonella in Powdered Dairy Products

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The Journal of Dairy Sciences reports that a team of researchers from China (Zhao et al. J. Dairy Sci. 100:3480–3496  May 2107) developed a new method for the detection of Salmonella in infant powdered milk.
The developed method is claimed to be rapid, specific, and sensitive. It is is based upon loop-mediated isothermal amplification technique combined with a lateral flow dipstick (LAMP-LFD) as the detection step.

Loop-Mediated Isothermal Amplification Technique (LAMP)

LAMP is a powerful new nucleic acid amplification method that detects very low levels of DNA. The method amplifies a few copies of target DNA with high specificity, efficiency and rapidity. The method uses a set of 4 specifically designed primers that recognize 6 distinct sequences of target DNA, and a DNA polymerase.
The cycling reaction can result in the accumulation of 109 fold of copies in less than 1 hour. The method is claimed to be more specific and less susceptible to interference than PCR, it is very fast, without the need of denaturing step.
 

Target Genes

The target gene invA encodes a Salmonella invasion protein and is thus considered a virulence gene located on Salmonella pathogenicity island (SPI), and is used frequently for the detection of Salmonella. The SPI4 region includes genes from siiA to siiF that are important for adhesion to polarized epithelial cells, and plays an important role in Salmonella pathogenicity.
The authors claim that this is the first attempt to use LAMP and the siiA gene to detect Salmonella.

 Lateral Flow Dipstick (LFD)

Lateral flow immunoassays dipsticks are used routinely to detect pathogens in food. Lateral flow dipstick use a sandwich type ELISA and the majority use polyclonal antibody as a capture antibody and a monoclonal antibody as the detection antibody. The antibodies are fixed on a hydrophobic membrane in immobilized in lines. Their role is to react with the analyte bound to the conjugated antibody. Recognition of the sample analyte results in an appropriate response on the test line, while a response on the control line indicates the proper liquid flow through the strip.
In the LAMP-LFD assay LFD strip is inserted into a tube that allows the strip to be immersed in the amplified sample. The sample migrates through the conjugate pad, which contains antibodies specific to the target analyte and are conjugated to colloidal gold and latex microspheres. The sample, together with the conjugated antibody bound to the target analyte, migrates along the strip into the detection zone
A number of researchers have combined LAMP with LFD. In this combination the LFD is soaked in LAMP amplified sample and the liquid travels by capillary action across the membrane to react with the antibodies and provide a color band.

Elimination of carryover Contamination

The high sensitivity of LAMP can become its largest potential disadvantage because trace left over material can be amplified and detected, causing false positive results, after several times of detection in the same place. Therefore, there is a need to eliminate any contamination from previous LAMP reactions.
To reduce incidence of LAMP contamination, the authors applied propidium monoazide (PMA) to eliminate carryover contamination of LAMP. The appropriate concentration of PMA diluted in water was applied to the working environment of any contaminated area and adequate light exposure conditions were used to complete the decontamination process.
 

Results

A very specific and conserved Salmonella target gene siiA was used to establish the LAMP-LFD detection method for Salmonella in powdered Infant formula.
In this study, the limit of detection of the LAMP-LFD for inoculated powdered infant formula, without enrichment was 2.2 cfu/g, which is 100x lower than the limit of detection for most PCR methods. A pure culture study of 21 Salmonella strains (with limited number of serotypes), and 60 inoculated samples of powdered infant formula yielded all positive results.  31 non-Salmonella strains (75% gram positive), including 20 non inoculated samples all yielded negative results.
 While more testing of this method is required, the reported method seems to be very rapid, specific, and sensitive for the detection of Salmonella in powdered infant formula.  PMA needs to be used to eliminate the LAMP carryover contamination.
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Multi State Outbreak of Listeriosis due to Soft raw Milk Cheeses

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The recall

The Center of disease Control (CDC) and the US Food & Drug Administration (FDA) are investigating a multistate outbreak of Listeria monocytogenes infections in raw milk cheeses.  Six people from four states were hospitalized, and two people from Connecticut and Vermont died. One illness was reported in a newborn.
The FDA found Ouleout cheese contaminated with L. monocytogenes. Epidemiological and laboratory data indicates that the source of the infections is the cheese made by Vulto Creamery of Walton, NY. Whole Genome Sequencing (WGS) performed on clinical isolates from all six ill people shows that the isolates are closely related genetically. This close genetic relationship provides additional evidence that people in this outbreak became ill from a common source.
The same strain of Listeria was identified in samples taken from three intact wheels of Ouleout cheese collected from Vulto Creamery. As a result on March 7, 2017, Vulto Creamery recalled all lots of Ouleout, Miranda, Heinennellie, and Willowemoc soft wash-rind raw milk cheeses.
The Connecticut Department of Public Health collected leftover cheeses from the deceased person’s home in Connecticut. The outbreak strain of Listeria was identified in a leftover cheese that the family identified as Ouleout cheese from Vulto Creamery.
The New York Division of Milk Control and Dairy Services collected three intact wheels of Ouleout cheese from the Creamery during a joint inspection with FDA. The outbreak strain of Listeria was identified in samples taken from the three wheels of cheese. Investigations concerning this outbreak are ongoing, and more cases are believed to become linked in the future.
The Company recalled cheeses of Ouleout, Miranda, Heinennellie, and Willowemoc soft wash-rind raw milk cheeses. The cheeses were distributed nationwide, with most being sold at retail locations in the northeastern and Mid-Atlantic States, California, Chicago, Portland, Oregon, and Washington, D.C.
On March 11 the FDA had increase the recall to include all the lots of the previously recalled cheeses and four additional cheeses.  As a result Vulto Creamery has recalled the following eight cheese items: Heinennellie, Miranda, Willowemoc, Ouleout , Andes, Blue Blais, Hamden & Walton Umber due to potential contamination of Listeria monocytogenes

Creamery History

Jos Vulto, an artist in trade, came to the United States from the Netherlands in 1990.  According to the company’s website, before Vulto started the business, he “had been making cheese in his apartment, in Brooklyn NY, for about five years, aging it under the Brooklyn sidewalk. He had never set out to become a cheese maker but after half a year of experimenting and favorable reception of some of his creations, he started to explore the possibility of starting a creamery.”
Expanding his business, he moved to Walton, N.Y., in the Catskills in 2012, closer to the source of his milk. Ouleout was an instant hit when it came out a few years ago. Mr. Vulto quickly earned a reputation among cheese lovers. When Vulto started creating Miranda in 2012, his aim was to make something that evoked his immediate geography.
During aging, the cheese are washed with Meadow of Love absinthe, made by Delware Phoenix Distillery (down the street from the creamery) from a variety of herbs, many grown in New York State. “I wanted something hyperlocal,” Vulto says.  “When Miranda is at its best, the influence of the absinthe wash is forward without being overwhelming,”. “The flavor is a complex but well-balanced swirl of brothy, meaty, and earthy, with nutty and grassy notes and a hint of fried onions on top.”
While getting accolades for the cheeses, the operation of manufacturing these cheeses was amateurish, with 3 part time employees and handmade operation, with limited controls over manufacturing.

The Lawsuit 

The widow of Richard Friedman, Vermont resident Veronica Friedman, has filed suit against Vulto Creamery after their cheese tainted with Listeria hospitalized her husband and led to his death. Ms. Friedman is alleging wrongful death as well as emotional and financial damage.
The Friedman’s purchased raw milk cheese that was manufactured by Vulto Creamery, cheese contaminated with Listeria, sometime in early October. Mr. Friedman’s symptoms began to take hold around October 11, 2016, when he went to the Emergency Room at Brattleboro Hospital. He was transferred to Dartmouth-Hitchcock medical center on October 12, where he stayed for a week and a half before being transferred to Mt. Ascutney Rehab in Windsor, Vermont. On October 31, at the rehab facility, Richard Friedman suffered a massive stroke, and was airlifted back to Dartmouth-Hitchcock where he died on November 2, 2016. The stroke was caused by the Listeriosis infection.

Advocates of Raw Milk

Advocates of raw milk believe that pasteurization destroys much of the beneficial bacteria in raw milk, enzymes and micro nutrients found in raw milk, and that the risk of bacterial contamination is very low given today’s modern, well-managed dairies. Others simply prefer the taste and freshness of locally produced milk over the longer shelf life and additives in commercial milk.
Some consumers say raw milk has more flavor and makes better cheese. Others choose unpasteurized milk as part of a broader shift away from processed foods, which are increasingly seen as unhealthy.
Raw milk has garnered increasing interest and attention nationwide in the last 10 years or so, as a small, but growing, segment of nutrition-conscious Americans choose it over commercially produced and pasteurized milk for taste and health reasons. 
Raw milk products are illegal in 20 US states, can be obtained from farms in 25 states and are available in shops in 13 states. EU countries make their own laws but products made with raw milk must be labeled. About a fifth of French cheese is made using raw milk.
Europeans have eaten raw milk cheese for hundreds of years. In France, for example, 15 percent of its cheese is made of unpasteurized milk, according to French Agricultural Statistics (http://www.agreste.agriculture.gouv.fr/IMG/pdf_primeur264.pdf). The thinking is that when milk is cooked, or pasteurized, many of the flavor-rich enzymes are destroyed.
In the United States, regulations on raw milk cheese are less stringent than in Europe, where more steps are required to ensure that there is no contamination.

The FDA and CDC position on Raw milk Cheeses

The FDA claims that there is a 50- to 160-fold increase in the risk of listeriosis from a serving of soft-ripened raw-milk cheese, compared with cheese made from pasteurized milk.
A mild heat treatment that kills 99.9% of the bacteria (3 log10 reduction) in bulk raw milk before cheese-making, would reduce the mean risk approximately 7-fold to 10-fold, compared with the baseline estimate for raw-milk cheese. This intervention is not full milk pasteurization.
Properly applied, full milk pasteurization kills all bacteria in raw milk. Testing the bulk milk used to make raw-milk cheese reduces the risk approximately 27-fold to 37-fold, but is less effective than testing raw-milk cheese lots, and still results in higher risk than the baseline risk estimate for pasteurized-milk cheese.
According the FDA, an analysis by the Centers for Disease Control and Prevention (CDC), between 1993 and 2006 more than 1500 people in the United States became sick from drinking raw milk or eating cheese made from raw milk. In addition, CDC reported that unpasteurized milk is 150 times more likely to cause foodborne illness and results in 13 times more hospitalizations than illnesses involving pasteurized dairy products.
Raw milk-related outbreaks are more common in states that allow the legal sale of raw milk for people to drink than in states that do not allow its sale. In addition, raw milk sales in one state can lead to outbreaks in neighboring states.
As reported before, this recall comes on the coattails of the cheese distributed by Deutsch Käse Haus of Middlebury, Indiana that included products sold under various brand names, including Sargento, Taylor Farms, Country Fresh, Choice Farm, MDS Foods, Meijer, Sara Lee, Guggisberg Cheese, Biery Cheese , and Saputo and others. These were all pasteurized milk cheeses. However in that case, no one has been reported sick in the outbreak.
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Listeria contamination at Deutsch Käse Haus forced nationwide cheese recall

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The recall of cheeses due to the presence of Listeria monocytogenes in Deutsch Käse Haus caused a snowball effect since Deutsch Käse Haus is a business–to-business provider of cheeses.
Once a food recall is issued, each company that receives the contaminated products has to look at how contamination may have spread through its own plant. The situation becomes more complicated as supply chains grow longer and longer. The globalization of food supply chains makes widespread outbreaks more likely, and in some ways more difficult to track.
It is hoped that the new FDA regulation as shown in the draft “Control of Listeria monocytogenes in Ready-To-Eat Foods” will eliminate the repeat of the ripple effect of recalls.

How Deutsch Käse Haus Started the Snowball

On January 30 the Tennessee Department of Agriculture took a sample of the Amish Classic Colby from a store in Trenton, TN, and found it to be contaminated with Listeria monocytogenes (LM). By February 9, they posted an alert announcing a recall of Amish Classic cheeses and Meijer branded cheeses, all made by Deutsch Käse Haus, a company owned by Michigan Milk Producers association since fall 2016. 
 
Since Deutsch Käse Haus is a business–to-business provider, a number of their customers were required to recall their products. The customers of these customers had again to notify their customers, resulting in a snowball effect.
The voluntary recall covered products made at Deutsch Käse Haus factory between September 1, 2016 and January 27, 2017. All the recalled products were produced by Deutsch Käse Haus. Meanwhile, all production has been suspended at the LaGrange County plant while the Food and Drug Administration (FDA) officials investigate the cause of the contamination.

The Snowball Effect

Sargento Foods Inc 

Sargento recalled seven of its branded sliced and shredded cheese products made by Deutsch Käse Haus. Products included Ultra Thin Slicked Longhorn Colby and Chef Blends Shredded Nacho & Taco Cheese. These products were made on the same line as five other products that Sargento recalled.

Taylor Farms

Secondary recalls related to Listeria discovered in cheese produced by Deutsch Käse Hausis have begun, with Taylor Farms recalling 6,630 pounds of chicken salad and pork products since they contain recalled Sargento cheese. The products packaged under the Signature Cafe and H-E-B brands were recalled. The problem was discovered on Feb. 10, 2017, when the establishments were notified of the recall by Sargento Foods, their supplier of Bevel Shred Pepperjack cheese products.

Country Fresh

Sargento’s products were also used by Country Fresh LLC in a number of cooking and snacking products. The firm recalled 2,552 cases of various kinds of stuffed mushrooms and other snacks that contained Sargento cheeses that were produced and packaged from February 6–9, 2017.

Choice Farm

It’s unclear if the cheese recalled by Choice Farm came from Sargento or Deutsch Käse Haus. The recall pertains to just seven trays of individually-wrapped mushrooms in the following flavors: Traditional Gourmet Portabella Mushrooms, Pizza Style Portabella Mushroomsand/or Stuffed Mushrooms. The products were sold on Feb. 10 at selected stores in Texas and Kansas.

MDS Foods Inc.

MDS Foods cut and packaged cheese from Deutsch Käse Haus, before distributing it under the Amish Classics brand. The firm recalled six cheese products that were found to have Listeria, and another 20 due to potential contamination. The cheese was labeled under various brands such as Amish Classics, Meijer, Deli Made EZ, Old Tyme, and Deli Readi.

Meijer

Meijer recalled its branded Colby cheeses after receiving notice from their supplier MDS that uses Deutsch Käse Haus Colby cheese. All Meijer branded “Colby Cheese” and “Colby Jack Cheese” sold in Meijer’s in-store deli counters (between from Nov. 10, 2016, through Feb. 9) were included in the recall.

Sara Lee 

Sara Lee recalled 734 cases of two types of cheese that were distributed to food retailers in Alabama, California, Louisiana, Michigan, Pennsylvania, and Texas. Three brands of cheese produced by Deutsch Käse Haus LLC and two brands of salads produced by Taylor Farms and included cheese recalled cheeses from Deutsch Käse Haus.

Guggisberg Cheese 

Guggisberg Cheese, which owns Deutsch Käse Haus, recalled a dozen products, mostly cheese available at deli counters. The affected products were manufactured both by Guggisberg Cheese, Inc. and by Deutsch Käse Haus, under the Guggisberg label. These products were packaged in clear plastic and sold primarily in retail stores at deli counters and deli cases.

Dutch Valley Food Distributors, Schlabach branch  

On 2/15/2017 the firm recalled products after they were notified by Deutsch Käse Haus that various cheese product they received may have been contaminated with LM. 

Biery Cheese

On 02-15-17 the firm was notified by Deutsch Kase Haus, that they supplied Biery Cheese with various type cheeses that may be contaminated with LM. These products were packaged at Biery in Louisville, OH and distributed to distribution centers.

Saputo Inc 

Saputo recalled certain Gouda cheese products after having been notified by Deutsch Kase Haus, that these products may have been contaminated with LM. The recalled products were sold to retailers nationwide. The Great Midwest Applewood® Smoked Gouda cheeses were sold primarily in retail stores at deli counters and deli cases.

How does Listeria Enter the Products?

Listeria Monocytogenes is present all around us, mainly on dust on the ground. Once Listeria enters into a manufacturing facility it is difficult to get rid of it. The primary reason for it is that LM tolerates salty environments and cold temperatures and can even continue to grow at temperatures as low as -5˚C. It is difficult to eliminate it; therefore the focus must be on prevention.
Contaminated boots can allow Listeria to enter the plans. Drains can harbor Listeria and must be properly maintained.  It is important to keep the factory floors dry at all times, since Listeria like most other bacteria needs water to grow.
In the FDA  Draft Guidance for Industry: “Control of Listeria monocytogenes in Ready-To-Eat Foods” there are detailed recommendations on how to control Listeria. The FDA encourages a “seek and destroy” approach.

FDA new rules RTE products- Listeria

For the first time, FDA has a legislative mandate that will require comprehensive prevention-based controls across the food supply to prevent or significantly minimize the likelihood of problems related to LM.
 
Facilities have “one free pass” of detecting Listeria in the environment and continue production, without a need to stop production. The finding still requires the performance of root cause analysis, extensive cleaning, sanitation, retesting, and investigation.
In the draft, there is a differentiation between low risk (do not support more than 1 log of growth) and high risk products. This differentiation affects the monitoring regiment as well as corrective action that need to be taken.  The guidance discusses product formulating as a mean to control of Listeria. The formulation must limit the growth of Listeria to less than one log. To be considered Listeria reduction a process must reduce it by 5 logs.
 
There are instructions on how to develop a robust environmental, sanitation and supplier verification programs. The goal is to find Listeria and eliminating the source of contamination. There is an emphasis on record keeping. There is a lengthy discussion on corrective actions should an environmental sample be found positive.
 
If LM is detected on Food Contact Surfaces (FCS), the food should be reprocessed, diverted or destroyed. The firm should consider a recall.
The guidance includes recommendations for controls involving personnel, cleaning and maintenance of equipment, and sanitation, as well as for treatments that kill Listeria monocytogenes and formulations to prevent it from growing during storage of the food between production and consumption.
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A Food Recall’s Ripple Effect: What We’ve Learned from Valley Milk Products

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The Valley Milk Products recall resulted in a subsequent ripple effect of recalls affecting over 30 companies. As this food safety event has played out over the last several months, it hWaterdropFotolia_9972077_Mas also raised several questions on how the industry should react and handle these types of chain-reaction-like recalls. The full article can be found on the Food online site.

The Ripple Effect

As reported i n details (1, 2, 3 ) The primary recall of Valley Milk Products (VMP) resulted in a ripple effect to a secondary group of companies that used VMP. 
The Ripple Effect Turns Tertiary As described in the Food online article we are currently observing several tertiary effects — companies that used products of the secondary group of products or products that were manufactured by a third party on lines where VMP were processed — of the VMP recall.

Important Facts

No Salmonella was reported to be recovered from VMP or the recalled products. None of the companies that recalled their products due to VMP had experienced any problems or got complaints about the recalled products, and no illnesses have been reported caused by these products.

Questions Raised by the Recalls

First, “Why did VMP refuse to recall products immediately after Salmonella was found in its processing environment?”  Many problems could have been avoided if they did.
Second, “Why did it take several months for the FDA to recall the products and stop their sale?” If the products are dangerous to the public, they should have been removed from commerce immediately after the discovery of the contamination, not several months later. The recalled products were in commerce for several months before the recall with no single report of illness due to the consumption of the products. Therefore, one should pose the questions, “Were the products contaminated in the first place?” and “Were all parties being overcautious?”
Third, a number of laboratories tested the related products and did not recover any pathogens. If the products were contaminated, “Why did so many labs fail to detect pathogens?”
Fourth, “Is there a better way to handle the chain reaction of this type of recall; where trace quantities of a potentially contaminated product get embedded in so many other products?” In the age of the Internet, it shouldn’t take months to complete a recall.
Finally, the most important question: Has the pendulum swung too far by the FDA demanding companies recall products that might be perfectly safe? If we accept GMA’s survey results demonstrating the financial impact of a recall is on average up to $30M, the cost of all the recalls due to VMP has been coming close to $1 billion. All these recalls took place without a single reported illness and without finding of Salmonella in any product.
While the infective dose of Salmonella varies with serotype, for non-typhoidal salmonellosis, the infectious dose is approximately 103 bacilli. Therefore, is it justified to recall so much good product for an infinitesimal chance it contains Salmonella?
Did FDA and the companies involved use too much caution?  How could the situation be handled better? Your opinion is important to us.