Food safety is top of mind for today’s food processors and consumers, and processors of meat and poultry products need to make sure their food contains as few unwanted microorganisms as possible. Animals are rife with microbial organisms, including some very significant human pathogens—most notably Salmonella, Campylobacter, and pathogenic E. coli.
According to CDC, 1.4 million cases of foodborne illness and more than 450 deaths are attributed to Salmonella infections in the U.S. annually. Campylobacteriosis is the second-most frequently reported cause of foodborne illness, and Campylobacter jejuni is the most common strain that causes illness. CDC estimates 1.3 million campylobacteriosis illnesses each year in the U.S. When it comes to E. coli, while most strains are harmless to humans, Shiga toxin-producing E. coli (STEC) can cause severe illness. CDC estimates that 265,000 infections occur each year in the United States and, due to its ease of infection and high mortality rate, STEC is among the most feared foodborne pathogens, by processors and consumers alike.
As we increase our understanding of how pathogen contamination occurs, regulations evolve as well. For example, USDA Food Safety and Inspection Service (FSIS) implemented a revised Salmonella and Campylobacter testing program in 2016 while also replacing its Salmonella-specific sampling set approach with a routine sampling approach for all USDA FSIS-regulated products that are subject to verification testing. Salmonella and Campylobacter performance standard verification samples are now taken as part of a “moving window” sampling approach, and the results are used to determine if an establishment is meeting the performance standard on a continuous basis.
More recently, CDC announced new goals as a part of its Healthy People 2020 initiative to drastically reduce the number of foodborne illnesses caused by some of these pathogens by more than 50,000 cases—a goal that will require cooperation and reduction efforts from both consumers and processors.
Consumer advocacy groups also expect processors to shoulder a greater responsibility from a foodborne illness prevention perspective. In January 2020, a law firm filed a petition with USDA to completely ban more than two dozen strains of Salmonella entirely from meat and poultry samples; unlike STEC, Salmonella is not currently considered an adulterant. Government agencies around the world are taking similar steps to reduce pathogen contamination; however, increased regulations place a greater demand on food processors to limit pathogen exposure and contamination as much as possible, lest they suffer a costly recall.
Most foodborne illnesses caused by meat and poultry products occur when consumers ingest these pathogens on improperly handled or cooked product. Many of the most dangerous pathogens live in specific parts of the animal or originate in the farms on which they were raised, but, during slaughter operations, contamination from the farm can spread to processing facilities through bacteria on the skin and intestine. Proper sanitary operations and the use of systemic antimicrobial interventions are necessary to minimize the contamination occurring during slaughter and further processing, if the carcasses are fabricated into parts and comminuted (e.g., ground or mechanically separated non-ready to eat) products.
However, processors can go beyond basic intervention steps to ensure that products delivered to consumers are as safe as possible. Two of the best ways to do this are well-designed environmental monitoring programs and utilization of modern pathogen detection technologies.
Innovations in Poultry and Meat Testing Methods
Testing for pathogens in meat and poultry products can be especially arduous due to the complex nature of the matrices. Detection is often assessed at the primary production level—in broiler carcass and/or in parts rinses and in raw meat. Competitive microflora in all of these types of samples can impact the growth of Salmonella required for detection in most culture-based methods. In addition, confirmation procedures become complex when associated microflora are also recovered in most selective agars. Therefore, traditional agar methods can struggle to rapidly and accurately assess the presence of Salmonella and Campylobacter in poultry products.
Through the early 2000s, DNA-based methods commonly utilized polymerase chain reaction (PCR) to help amplify samples. PCR methods typically require multiple steps to process enriched food samples and amplify target DNA for detection of pathogens. More recently, new molecular tests have been developed with loop-mediated isothermal amplification (LAMP) technology to simplify and quicken the testing process.
Whereas PCR methods typically rely on two primers to copy and amplify a sample’s DNA and then read the strands, LAMP methods use between four and six primers, which, in addition to displacing the target DNA strand, also loop the ends of the strands together before the amplification process. This looping structure accelerates the reaction and increases the sensitivity of the test, allowing for a much, much larger accumulation of the target DNA.
LAMP technology also allows for minimal transfer steps instead of the multistep process used in PCR methods. A process with fewer steps allows labs to process more samples in less time, meaning reductions in cost, time, energy, and manpower.
The advent of molecular pathogen testing methods has also allowed technicians to become much more specific and accurate in their testing. For example, many processors are testing for specific serotypes of concern.
Pathogen Environmental Monitoring Programs
Pathogen testing of finished products, while crucial, should be viewed as only one part of a comprehensive pathogen prevention plan. The implementation of these technologies as part of a well thought-out, well-executed pathogen monitoring program is necessary for processors to prevent contamination with pathogens in ingredients and during processing operations.
Pathogen environmental monitoring (PEM) programs are often considered to represent a proactive approach to microbial food safety. These programs can identify challenges and pathogen sources within the manufacturing environment before they lead to contamination of finished food products.
PEM programs are typically used to validate and verify the suitability and effectiveness of food safety systems and to provide early indication of potential food safety hazards. The validation of sanitation procedures and other control strategies typically requires the use of multiple environmental monitoring approaches, including adenosine triphosphate (ATP) testing, to assess cleaning and total plate count (TPC) methods.
Often, use of these tests is supplemented with pathogen testing to identify specific harborage sites that allow for pathogen growth or survival. The process used to identify specific harborage sites or niches (e.g., as part of validation or similar type efforts) is often referred to as the “seek and destroy” technique. In addition to validation and verification, testing of environmental samples for pathogens is used to support root-cause analysis efforts and to verify that corrective actions taken are effective in addressing specific pathogen-related problems. These activities may be part of “for-cause” and “not-for-cause” investigations.
These tests are much less effective when done in isolation rather than as a comprehensive, custom PEM program tailored to a producer’s specific products and specific facility, which is designed to ensure that no likely harborage site is left untested. But, the specifics of how the plan is executed are just as important as the plan itself.
Small details, from the amount of pressure applied to a sponge to the specific locations tested (e.g., a floor crack vs. an adjacent uncracked floor section), can have a huge impact on whether pathogens are detected. Hence, it is important to design the sampling plan to avoid intentionally or unintentionally providing incentives for the sample collectors to not collect samples that would likely yield pathogen positives. For example, setting numeric targets or key performance indicators for the percentage of positive PEM samples may simply lead to sample collectors not collecting samples that will likely yield positives. The goal of a PEM program is to find and eliminate pathogen contamination in the processing environment, and this goal cannot be compromised.
Technology also plays a large role in pathogen detection. Whether a producer is testing samples as a part of a PEM program or testing finished product or ingredient samples, a test is only as useful as the technology instrument allows.
The entire food industry is striving to meet the highest safety standards, and meat and poultry processors are no exception. The best course of action is to adopt a total solution, from sample collection and preparation to monitoring and detection. Whether it’s Salmonella, Campylobacter, E. coli, or another pathogen, processors can utilize advancements in technology to mitigate risk at every step while improving operational efficiencies and productivity.