Sample6 DETECT: How Does it Work
Over the past 2 years, I have frequently joined presentations, demonstrations and field visits on our first product, Sample6 DETECT/L. The audiences have ranged from microbiologists to plant workers, to plant managers to corporate vice presidents to investors. The conversation always follows a similar pattern. Everybody gets the “why” immediately: a Listeria assay that produces results in less than a single shift is better than diagnostics that takes 24 hours or more. Plant and production teams focus on the logistics opportunity to deliver safe products faster. Quality teams consider the opportunities to test closer to the product. Sanitation teams are excited by the ability to receive clear actionable information and microbiologists are excited to use this type of diagnostic to investigate presumed positives prior to sanitation. We hear unanimously that the opportunity to test and retest when conditions may still be representative will revolutionize testing, investigations and resolutions. But, no matter who I’m talking with, the next question is always the same, “How can you deliver results so quickly, how does it work?”
As Director of R&D, I’m proud of the work my team has done to build this product and happy to share some insight on how it works. The short answer is that the DETECT/L assay does not require the 24-48 hour enrichment step that most other assays need.
Let’s go through a little background on why other assays require enrichment:
Most existing assays require enrichment to multiply the number of Listeria cells in a sample so that there are enough of them to detect. This is because many techniques are not sensitive enough to detect the low number of cells encountered in an environmental sample. This is not an inherent issue for DETECT/L. With our technology, we can routinely detect a single healthy Listeria cell.
Simply put, a perfectly specific test is one that does not detect things that it should not. Assays for Listeria should not detect dead Listeria cells. Most assays available today need enrichment to achieve specificity because most existing assays can’t tell the difference between living cells and dead ones. Picture an episode of CSI where the hero collects a carelessly discarded toothpick, which is then processed in the lab and ultimately snares the criminal. The technology used to process the toothpick is called PCR. This technology is checking the sequence of the DNA found on the toothpick and comparing it to DNA of the suspect. The DNA found on the tooth pick was from dead cells and the DNA collected from the suspect was from living cells. For forensics, this works well.
When protecting food from pathogens, dead cells are to be expected. They are a result of effective cleaning measures in environments that have conditions, which foster the growth of pathogens. Only live cells present a risk to the food. Existing assays manage this issue through multiplication, or enrichment of living Listeria cells. In contrast, DETECT/L cannot detect a dead cell. In fact, we absolutely need living Listeria cells to generate a positive signal. The next question I am typically asked is:
“Is the next version of the assay going to be even faster?”
While that is largely a topic for a future post, I will say a couple of things. First, the technology we are developing is young. Unlike PCR and immunoassays, which have been under development for decades, the limits of our technology are just starting to be explored. We believe there are ways to both reduce the time and simplify the overall process. We believe that with the right technology in food processing plants, we can help make food safer. My team will continue to push the limits of DETECT/L and future assays from Sample6. We look forward to sharing this work with you.