Huang et al. (2016) summarize evidence from a progress report on the United States Foodborne Diseases Active Surveillance Network (FoodNet) that shows increasing use of culture-independent diagnostic testing (CIDT) methods such as polymerase chain reaction (PCR) for detecting pathogens in patients.1 The paper covers FoodNet activity between 2012 and 2015, focusing on the incidence of foodborne disease (FBD) in the United States within the population. During this period, the authors note that use of CIDT increased.
As a federal resource, FoodNet follows the appearance of FBD pathogens in the general population, aggregating and tracking records throughout the US. With this information, food safety officials can monitor and react swiftly to outbreaks, as well as direct resources proactively to maintaining food chain safety.
In 2015, FoodNet reported 20,107 cases in the population where laboratory culture confirmed infection with an FBD pathogen. This resulted in 4,531 hospitalizations and 77 deaths. Huang et al. also note that a further 3,112 cases occurred, with FBD confirmation arising from CIDT. Although CIDT may not be sufficient to identify the subtype or strain involved in the infection, there is a rising trend in its application for medical diagnosis.
CIDT methods are also available for food-safety testing. Testing is based on molecular methods that focus on pathogen genomic material such as nucleic acid sequence, antigenic markers or toxin signatures. These tools enable rapid detection in hours, rather than the traditional assays that need days for enrichment and in vitro culture.
Furthermore, using sensitive techniques such as PCR, laboratory technicians can screen foodstuffs for trace amounts of pathogen. Positive identification then flags the need for confirmation by traditional culture. However, if a product is clear, the rapid testing protocol clears it much faster than traditional methods.
As producers such as Florida Urban Organics have found, this strategy pays off in a multitude of ways. Not only does the testing equipment occupy a much smaller footprint in the laboratory, but the faster turnaround also reduces inventory storage on-site, freeing up valuable production space for microgreens. According to the company, switching to the SureTect PCR system (Thermo Scientific) gained their retail products an extra week in shelf life simply by speeding up the testing process.
It’s not just fresh produce that benefits from molecular testing for food safety protocols; poultry pathogen testing has also gone molecular with MicroSEQ™ and TaqMan™ assays for Salmonella species (Thermo Scientific). Not only do these tools detect low amounts of microbial contamination, but they also function well in situations with high backgrounds of competing flora. The SureTect Listeria PCR assay offers similar rapid and sensitive results in a wide variety of food matrices.
Producers should also consider molecular testing for environmental monitoring; they can use CIDT to monitor hygiene and cleaning protocols within processing plants or keep an eye on water quality, for example. With results available quickly, the food industry can take immediate steps to avoid product contamination or a recall.
For routine monitoring, switching to CIDT methods could benefit both food safety and production for many producers. Although it does not replace traditional culture testing, molecular testing provides reliable confirmation within hours and is a useful screening strategy.
Learn more about molecular testing for food safety in our food community.
1. Huang, J.Y. et al. (2016) “Infection with Pathogens Transmitted Commonly Through Food and the Effect of Increasing Use of Culture-Independent Diagnostic Tests on Surveillance — Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2012–2015“, Morbidity and Mortality Weekly Report MMWR / April 15, 2016 / Vol. 65 / No. 14 US Department of Health and Human Services/Centers for Disease Control and Prevention
Molecular Testing and Food Safety FAQs: https://www.thermofisher.com/blog/food/molecular-testing-and-food-safety-faqs/