Rapid result

2019-03-08 06:07:02

By Nicole Johnston in Washington DC FAST food is a way of life for millions. Now there’s also a fast way of preventing food poisoning—a biosensor that can detect the bacterium Salmonella typhimurium in a matter of minutes. Robert Brackett and colleagues at the University of Georgia and the Georgia Institute of Technology have devised an optic sensor that can identify the presence of the bug, notorious for causing food poisoning from undercooked chicken or contaminated surfaces, in as little as ten minutes. This is a huge leap from the several hours to a few days that similar devices and current laboratory methods demand (This Week, 15 May 1999, p 20). The device uses two translucent strip-shaped sensors—a test strip coated with antibodies specific to S. typhimurium, and a reference strip with a nonspecific antibody. As wash fluid from the chicken passes over both strips, the organisms are trapped by the antibodies in the test strip but not the reference strip. A laser beam shone through the strips registers a pattern of light on an output device. When the bacteria are present and bind to the test strip, they interfere with the beam path, changing the phase of light and causing a different output signal compared to the reference strip ( Journal of Food Protection, vol 62, p 431). According to Mike Doyle, director of the Center for Food Safety and Quality Enhancement at the University of Georgia, today’s immunological tests take as little as eight hours, but are not as likely to pick up pathogens as traditional microbiological methods,