September is Food Safety Education month and, in recognition, the American Frozen Food Institute (AFFI) and the International Fresh Produce Association (IFPA) will host a virtual Food Safety Forum, where they will convene global research experts, industry professionals, and food safety policy leaders to discuss emerging issues related to non-cultivable foodborne pathogens.
Enteric viruses such as hepatitis A, norovirus and protozoan parasites like Cyclospora and Cryptosporidium are foodborne pathogens associated with different types of foods, and which have been implicated in outbreaks. Concerns about these pathogens have led to calls for more routine product testing and surveillance across the food supply chain; however, detection of these pathogens has several limitations.
Speakers at the Food Safety Forum will discuss technical challenges and regulatory questions associated with detection of these pathogens and interpretation of results.
Following are excerpts from interviews with IFPA’s Jennifer McEntire, Chief Food Safety & Regulatory Officer, and AFFI’s Sanjay Gummalla, Senior Vice President of Scientific, discussing the significance of the forum and the scientific discussions from the perspective of food safety and public health.
Question: Why is the Food Safety Forum addressing non-cultivable foodborne pathogens now and why are AFFI and IFPA encouraging participation from industry, government and academia?
McEntire (IFPA): While concern has grown over the prevalence of these pathogens in foods, they present distinct detection issues not seen with bacterial pathogens. This forum will delineate differences between bacterial and non-cultivable pathogens such as hepatitis A, norovirus and Cyclospora. For instance, they cannot be propagated through pre-enrichment, selective enrichment, or selectively plated, which are gold standards used in identification of bacterial pathogens such as Salmonella or Listeria. An awareness of this topic is relevant to all food safety professionals.
Gummalla (AFFI): Unlike bacterial pathogens that can be grown to high numbers in a lab, enteric viruses must be isolated from the food or environment by concentration and purification, followed by nucleic acid extraction, before a detection method such as PCR can be applied. The forum will help attendees better understand these steps and the implication of positive findings, and the regulatory and public health considerations. All stakeholders should have an improved understanding of this topic as calls for food product testing increase.
Question: Do these pathogens grow in foods? If we cannot culture these pathogens and they do not grow in food, how do we ascertain contamination?
Gummalla (AFFI): No, they do not grow in food and that is a good thing. But since these pathogens can’t be grown, the question we need to ask ourselves is, “is being able to detect a nucleic acid fragment synonymous with contamination?” While a suspected bacterial pathogen such as E. coli or Listeria monocytogenes can be cultivated in a laboratory to confirm presence and viability, there is no such possibility with non-cultivable pathogens. Instead, we use PCR-based methods, like testing for the detection of SARS-CoV-2 in clinical settings.
McEntire (IFPA): In FDA’s BAM detection protocol for Cyclospora, the agency does outline certain PCR thresholds, but there remain questions about the reliability of PCR testing in foods where these pathogens are both heterogeneously distributed and may occur only in low numbers. This situation leads to a complex and ambiguous regulatory interpretation of “what” constitutes “an indicator of contamination” and whether a nucleic acid finding determines contamination or adulteration.
Question: How is sample positivity currently determined?
Gummalla (AFFI): While a PCR test signal may be positive, evidence for food contamination remains unclear. Additionally, confirmatory approaches can support the original PCR-based positive finding, but none of these methods have been adequately vetted, published or routinely used by the technical community.
McEntire (IFPA): For Cyclospora specifically, the organism appears to have a complex life cycle, and is only infectious during one phase of its life. So even if there is a PCR positive, you can’t tell which version of the organism was there, even if it is viable.
Question: What other components can inform risk?
McEntire (IFPA): Given the limitations of testing and the uncertainty with what a positive test for the presence of nucleic acid may mean, there are a range of other factors that should be assessed during the review of a potentially positive PCR test result. This could include a review of the presence of worker illnesses at the farm or facility, a review of site sanitation and the use of Good Manufacturing Practices (GMP) or Good Agricultural Practices (GAP). It is important to understand the totality of public health risk to inform food safety decisions.
Question: What resources are available to assist these communities reducing their risk for these organisms?
Gummalla (AFFI): AFFI recently launched an Enteric Virus Control Specialist certification program in partnership with the International Food Protection Training Institute. This includes courses that address best practices in worker health and hygiene, controlled use of water, waste management, and sanitation of equipment and tools. The course is based on AFFI’s Enteric Virus Control Program, a free resource available to all produce growers and processors.
McEntire: IFPA and AFFI are working closely with FDA in support of industry prevention strategies for specific product- hazard pairs, including berries and hepatitis A, and we’ll share any new knowledge or insights gained. For Cyclospora, we have a technical bulletin free for industry use. But truthfully, we need to better understand this organism and routes of contamination. We do not want the industry to waste resources implementing programs that won’t have an impact.
Question: Why should food safety experts be interested in learning more about non-cultivable foodborne pathogens?
Gummalla (AFFI): We are at the crossroads of setting significant precedents in our approaches to determining “indicators of contamination,” “adulteration,” and ascribing “public health risk” associated with non-cultivable pathogens. It is important for all stakeholders in the food safety community to understand limitations in methods, how we assess contamination, and the regulatory enforcement and public health impact. We are excited to host the Food Safety Forum and drive scientific awareness, debate and understanding of this challenging topic. We welcome food industry professionals to join us virtually on September 21, 2022, at 11 a.m. Eastern.
This information was contributed by AFFI. For more information see www.affi.org/food-safety-forum.
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