The 2017 Biodefense World Summit
breakout session on food safety detection was a goldmine of information with a whopping 12 presentations. Whether it was nucleic acid aptamers as bioaffinity ligands for detection of human norovirus (try saying that three times fast!), rapid detection of Enterobacteriaceae
as indicator pathogen testing, or food-safety microbiology in the metagenomics era, there was a wealth of knowledge presented for those interested in food-safety detection.
Chris Taitt, PhD, from the US Naval Research Laboratory discussed the use of antimicrobial peptides as a broad-based detection method for pathogens. He highlighted the most common uses for rapid detection—food safety, environmental monitoring, biosecurity, and health monitoring—but also how he and his colleagues are looking for specific molecular markers for rapid detection. The most common approaches to rapid detection are nucleic acid-based technologies and immunoassays as they are sensitive and well-developed; however, they also require knowledge of the specific target (ie, you have to know which organism you’re looking for). Dr. Taitt noted that because of these gaps, we really need a broad-spectrum detection method without specific reagents. The use of antimicrobial peptides (AMPs) may be that new method for detection of cells. AMPs bind to multiple species and are stable to environmental extremes. The best part is that they are semi-selective, and so they can detect a broad range of targets. Dr. Taitt highlighted that a broad-based, semi-selective recognition platform, such as using AMPs, may be the next step in rapid detection in which discrimination is needed.
Lingwen Zeng, PhD, of the Wuhan Academy of Agricultural Sciences presented on nucleic acid biosensors for the detection of pathogen. He first discussed the conventional methods of detection (such as, culture, polymerase chain reaction testing, and antibody testing), highlighting several advantages for some of the tests—rapid detection, cost-effectiveness, etc—but, then he also pointed to substantially more disadvantages for each method—false-positives, expensive equipment, and more. He discussed the future role of nucleic acid biosensors; they can be rapid (several minutes), simple and convenient, and low-cost with no need for instruments. Moreover, he used tests for E. coli
0157:H7 to show the sensitivity of biosensors and hone in on their utility as a detection method that not only does not require an antibody, but is rapid, detects only complete bacteria, and doesn’t require expensive instruments.
Robert Buchanan, PhD, of the Center for Food Safety and Security at the University of Maryland made excellent points about the lower limits of detection, drawing attention to the realities of expectations. He also highlighted that promises that have been made of single-bacterial-cell detection are not deliverable. Perhaps one of his best comments was that “microbial testing is inherently ‘probabilistic’ in nature.” You cannot prove a negative; [you can] only disprove it. Dr. Buchanan noted that the only way to absolutely ensure the absence of microorganisms is to test the entire lot of food.
This particular breakout session on detection for food safety was highly engaging and brought about several gaps within the food-safety chain, specifically the wide variety of detection methods and the need for continuing research and development.