Test Detects Live E. Coli in Ground Beef

COLUMBIA, Mo.University of Missouri food scientists have developed a new test that detects live E. coli cells in ground beef in 12 hours, as opposed to older methods, which require up to two days for results. The researchers have successfully tested the technique on ground beef, chicken and eggs.

The two-step method distinguishes between dead and living E. coli cells by using a technique called a real-time polymerase chain reaction (PCR), a quick and reliable method for detecting and identifying pathogens in food. However, PCR cant differentiate viable from dead microbial cells; the presence of dead pathogenic cells may result in false-positive findings, which could lead to unnecessary product recalls. To prevent this, researchers stained samples with a dye called ethidium bromide monoazide. The dye cant penetrate live cells, but it can enter dead cells where it binds to DNA molecules and makes them insoluble and, therefore, invisible to PCR tests.