SPOTLIGHT

By Jennifer Williams and Dan Mallin, Ph.D.

Back to the Future: From STEC to Salmonella

Five hard-won keys to reducing the presence of pathogens

Animal product, Food, Ingredient, Cuisine, Dish, Beef

Photo credit: ShaneKato/E+ via Getty Images

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After being given the opportunity to present a point of view from our life’s work within food safety, we knew it would be around our beef food safety journey. The most time-consuming part of preparation was in how we would describe the past, present, and future. Beef is a delicious and nutritious protein, and for many Americans, it is consumed less than well done.¹ The debate around whether a consumer can or should have the responsibility of safe cooking preparation will be left for another time, as will the focus on the industry politics of the Shiga toxin-producing Escherichia coli (STEC) era. Rather, our focus is the key learnings that have led us to reflect on what did and did not work in the battle to reduce STEC-related illnesses. We also focus on how that work was achieved and the less-described sector of food safety—industry research and execution of food safety systems. Within our company alone, E. coli O157:H7 findings have been reduced 95 percent from the first year of testing in 2003 to now. At the outset of trim and ground beef product testing, most in or around the industry would not have believed that a drive to zero was possible. 

A Little Background

Laboratory methodology progressed in the 1980s and 1990s with regards to specificity, sensitivity, and cost. The ability to detect foodborne pathogens accelerated as did the ability find connections between those consumers with foodborne illness. In June 2001, a hands-on fight with E. coli O157:H7 began. While microbiological testing within the process itself was not new, the debate that spring and summer had turned to recent illness outbreaks related to ground beef and E. coli O157:H7. The U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) communicated its intent to make an additional rule and declare that E. coli O157:H7 was a hazard reasonably likely to occur in harvest, trim production, and ground beef processes and significantly increase its testing of raw ground beef and raw ground beef components.² Why is this an important point to remember? Many in the industry consider it a key moment when E. coli O157:H7 was declared an adulterant. The adulterant declaration had already happened almost 10 years before. It was the summer and fall of 2001 that USDA-FSIS intended to increase verification samples and communicated the intent to recall any product associated with a confirmed positive USDA-FSIS test from cleanup to cleanup. This was the key point in time that led to widespread industry testing of trim and ground beef and to further defining and supporting the production lot associated with microbiological results in the event of a downstream positive. As a result of widespread testing, the test results themselves would serve as feedback to the beef harvest decision-making process on an everyday, ongoing basis. These data were a key difference maker within the plant food safety team’s assessment of the process itself. 

“Within our company alone, E. coli O157:H7 findings have been reduced 95 percent from the first year of testing in 2003 to now.”
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Monochrome photography, Parallel, Black, Black-and-white, Line, White

Key #1: Focus on Food Safety Outcomes

In the summer of 2002, the daily receipt of results became the predominant obsession of plant teams. Our experience was that our food safety team, which included management, operations, food safety/quality assurance, and maintenance, was incredibly responsive to the data. We would get calls if the lab results were late by those looking for the positive and negative results. Pre-STEC testing, we were looking for others to follow up on key items, but now that same team was in search of us and those results. The following 18 months were a blur of research, in-plant data review, new process techniques, and, yes, increasing regulatory policy on enforcement. It would be impossible to unpack all  the positives and negatives of the regulatory enforcement policies, so suffice it to say that in the span of 5 years, the number of regulatory policy pages related to beef pathogen food safety increased at the same pace that the number of beef pathogen test analyses did.³ The in-plant impact from that increase in regulatory policy pages was as nerve-racking as the receipt of our daily test results. The key lesson learned for many beef food safety professionals who worked on the plant floor during the past 20 years is this: Focus on the food safety impact first, regulatory compliance second. If positive food safety outcomes are present, the regulatory enforcement actions are less likely. There were and are still exceptions to this rule or belief, but in general, this brings the first key learning: Focus on food safety outcomes.

Key #2: Food Safety Is a Team Effort

Now, let’s move on to what we can control. The academic and industry research identified the intestinal tract and the hide-removal process as key concerns with transfer of STEC to the carcass surface. We became obsessed with the details, relearning what pieces of the carcass were associated with certain lean points and connecting those test results with the process itself. We increased our data collection and monitoring observations to identify where cross-contamination or transfer might be occurring and then problem-solved that process step or created new harvest processes. Team members, supervisors, maintenance—anyone associated with the processes was invited to be creative and try new things that a few years later would become industry expectations. 

Millions were invested in machinery, labor additions, intervention strategies, and testing strategies in the beef industry. At the same time, industry food safety leaders made the deliberate decision to openly share data and learnings associated with beef food safety. The Beef Industry Food Safety Council, or BIFSCo, was born. Early each year, BIFSCo members openly share problems, discoveries, and solutions in a noncompetitive setting. Another key industry learning came with this experience—the awareness that even if one’s company doesn’t have a connection to a foodborne illness outbreak or recall, we are all affected by consumer and customer loss of confidence. As we draw nearer to BIFSCo’s 20th anniversary, our focus has become leveraging what we’ve learned combating STEC to the reduction of Salmonella-related foodborne illness. BIFSCo and industry collaboration illustrates the second key learning: Food safety is a team effort.

Key #3: Take Action on the Data

Before turning our attention to current and future beef food safety, it’s important to recognize the transition in STEC reduction that occurred. Somewhere in the middle of these last 20 years, the industry became the leading voice in this crusade. A key illustrative point of this leadership is that many in the industry took findings to USDA-FSIS to inform future policies. A case in point is the realization that a negative result is not always a negative result. As testing became implemented throughout the industry, more and more samples were gathered. While appropriate product test-and-hold strategies are still a pain point today, we realized that we had some unfortunate things happening with downstream samples. On one such painful day while poring over data together, we realized that previously tested negative trim had yielded a positive ground beef result. Those negative-tested beef trimming lots were sandwiched between positive lots. We decided that we would gather more data to determine how likely to occur this phenomenon was. As painful and scary as it was to discover that negatives were not always negative, this was an important discovery that was shared with industry and USDA-FSIS for one important purpose. Multiple positives within a sequence of testing signal that the process has shifted and must be considered differently with both possible root-cause identification and product disposition. This yields the third key learning for the food safety professional: Take action on the data. 

“Millions were invested in machinery, labor additions, intervention strategies, and testing strategies in the beef industry.”
Tints and shades, Monochrome photography, Black, Black-and-white, Line, Style
Monochrome photography, Parallel, Black, Black-and-white, Line, White

Key #4: Acknowledge Good Work and Adopt It

All the weapons within the STEC arsenal work to reduce findings of Salmonella: harvest dressing practices, reduction of contamination transfer, multiple-hurdle intervention strategies, data analysis, and microbial testing feedback. Unfortunately, Salmonella reduction in the meat and poultry world is not as simple as STEC mitigation strategies. Salmonella is not only more prevalent within the live animal setting, but it also is more complex in terms of the control strategy within the production process. In some ways, the STEC mindset may have put blinders on the food safety professional, as it’s not enough to have a sanitary harvest-dressing practice. Within the STEC journey, it was and is normal for academic and industry researchers to make new discoveries that become the single-minded focus of new work. Case in point: In the beef STEC battle, the hide-removal process became identified as the almost-always root cause of positive test results. As an industry, we’ve since come to realize that there are other places within the process involved in either the transfer or the outgrowth of pathogenic E. coli. It is critical that we avoid a simplistic focus on “smoking gun” theories. Reducing foodborne illness attributed to Salmonella will require discipline to gather more data on a broader platform than what STEC required. In the earlier days of industry collaboration on STEC actions, there were many who hotly discussed a given company’s point of view. Vigorous debate and discussion followed on testing methods for a number of years, and while we do not all agree on one way, we have progressed to a place where we can recognize ideas and work that did not originate from our own enterprises. We can now acknowledge each other’s contributions, adopt good work if it makes sense, and move on. The fourth key point in the food safety professional’s learning journey is: Acknowledge good work and adopt it.

Key #5: Don’t Let Perfect Get in the Way of Better

While cattle can carry pathogenic E. coli within their intestinal tract, they do not typically become ill from pathogenic E. coli.⁶, ⁷ Because their immune system is not highly responsive, STEC is typically not found in tissues of cattle, whereas Salmonella can be found in their lymph tissue.⁸,⁹ Another key difference is that many Salmonella strains survive at lower temperatures than STEC typically does and are less sensitive to competition by native microbial environment, meaning that initial chilling and cold chain management become even more critical.¹⁰ The complexities of Salmonella contamination within the supply chain and production process are numerous, and as a result, the solutions to this problem will be numerous. The hand-wringing over the complexity of Salmonella contamination within the food chain has, at times, stalled additional reduction of foodborne illness attributed to Salmonella. The reality is that within the next 10 years, we’ll look back and realize how much we did not know. This brings the focus back to key learning number one: Focus on food safety outcomes. 

Unlike with E. coli O157:H7, we know that in many cases, people must ingest more than a few cells of Salmonella to become sick.¹¹ It’s also understood that certain Salmonella strains display virulence factors that are more or less likely to lead to worsening human health outcomes.¹²,¹³ Coupling these two general known factors with the work that must be done at the start of a Hazard Analysis and Critical Control Points-based process to understand the products’ intended use brings us to where to start with Salmonella. A Salmonella reduction strategy built upon enumeration or limits of detection strategy, emerging virulence factors in certain serovars or strains, and product-based risk profiles can lead to better human health outcomes. In this day and age, it is difficult to be a gradualist in many professions and debates. However, we must not let perfect get in the way of better. Reduction in foodborne illness attributed to Salmonella must be the top priority. The next year will hold many discussions on regulatory framework and processes to define Salmonella objectives. Key learning point number five is: Don’t let perfect get in the way of better.

“Best practices for food safety are part of an ever-changing landscape as we learn more.”
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In Closing

The largest challenge that we have with Salmonella is purely how much we do not know. Although some within the industry are working on the general path of understanding enumeration, virulence, and product risk, there still are many unknowns. While live animal lairage conditions do impact levels of STEC within the intestinal tract, considerably more supply chain factors impact Salmonella and the live animal. Seasonality, regionality, and supply chain type all affect Salmonella prevalence, enumeration, and virulence factors. Couple these live-animal unknowns with the Salmonella organism’s ability to survive and thrive more broadly than STEC in the plant harvest, chilling, and processing environment. The number of unknowns with Salmonella cause and effect looms large, but this work has begun and is picking up speed in the research and industry communities. 

Through research, discoveries will be made and new approaches developed to implement better methods to realize this type of food safety impact. Best practices for food safety are part of an ever-changing landscape as we learn more. While there have been food safety giants who’ve led during this process, the names and faces of our food safety heroes are the thousands of people in the plants who implement the best food safety practices with agility, purpose, and ownership to provide safe and nutritious food to people they will never meet. 

References

  1. Røssvoll, E., et al. 2014. “Consumer Preferences, Internal Color and Reduction of Shigatoxigenic Escherichia coli in Cooked Hamburgers.” Meat Sci 96: 695–703.
  2. https://www.govinfo.gov/content/pkg/FR-2002-10-07/pdf/02-25504.pdf.

  3. https://www.fsis.usda.gov/wps/portal/fsis/topics/regulations/directives/10000-series.

  4. https://www.bifsco.org/.

  5. www.fsis.usda.gov: https://www.fsis.usda.gov/wps/wcm/connect/e0f06d97-9026-4e1e-a0c2-1ac60b836fa6/Compliance-Guide-Est-Sampling-STEC.pdf?MOD=AJPERES.

  6. Keen, J.E., et al. 2010. “Distribution of Shiga-Toxigenic Escherichia coli O157 in the Gastrointestinal Tract of Naturally O157-Shedding Cattle at Necropsy.” Appl Environ Microbiol 76(15): 5278–5281.
  7. Menge, C. 2020. “The Role of Escherichia coli Shiga Toxins in STEC Colonization of Cattle.” Toxins 12(9): 607.
  8. Samuel, J.L., et al. 1980. “Distribution of Salmonella in the Carcasses of Normal Cattle at Slaughter.” Res Vet Sci 28(3): 368–372.
  9. Webb, H.E., et al. 2017. “Salmonella in Peripheral Lymph Nodes of Healthy Cattle at Slaughter.” Front Microbiol 8: 2214.
  10. Semenov, A.V., et al. 2007. “Influence of Temperature Fluctuations on Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in Cow Manure.” FEMS Microbiol Ecol 60(3): 419–428.
  11. https://www.medscape.com/answers/228174-77482/what-is-the-infectious-dose-of-salmonella.

  12. Worley, J., et al. 2018. “Salmonella enterica Phylogeny Based on Whole-Genome Sequencing Reveals Two New Clades and Novel Patterns of Horizontally Acquired Genetic Elements.” mBio. https://doi.org/10.1128/mBio.02303-18.
  13. Johnson, R., et al. 2018. “Typhoidal Salmonella: Distinctive Virulence Factors and Pathogenesis.” Cell Microbiol 20(9): e12939.

Jennifer Williams in the vice president of food safety/quality assurance at Tyson Fresh Meats.

Dan Mallin, Ph.D., is the senior director of food safety/quality assurance at Tyson Fresh Meats. 

APRIL/MAY 2021

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