A new disc-based polymerase chain reaction (PCR) assay called GeneDisc reliably and reproducibly detects E. coli serotypes in ground beef, according to new research from the U.S. Department of Agriculture that was published in the December issue of Frontiers in Cellular and Infection Microbiology.
The technology permits simultaneous detection of multiple targets by real-time PCR, the researchers wrote. “It’s very easy to use, and it’s fast,” said Pina Fratamico, PhD, a microbiologist and lead scientist in the USDA’s Microbial Food Safety Research Unit. “We always knew what we were putting in, and we got perfect results with a detection limit of less than one CFU per gram.”
The GeneDisc assay differs from standard PCR approaches, which usually mix in a tube or plate. Instead, it uses discs divided into either 6 or 12 sections. “Each section can assay one sample,” said Dr. Fratamico. “There are wells in the central part of the disc where you put in your reagents and the DNA that you’ve extracted using extraction material that also comes with the kit. Then you use a vacuum to pull material into the outer wells and pop it into the thermal cycler machine and get results in a little over an hour. The flexibility, simplicity, and rapidity mean that it could be easily used by the food industry.”
The nine serogroups tested included STECS 026, 045, 091, 0103, 0111, 0113, 0121, 0145, and 0157.