Salmonella tape

Iowa State University researchers have developed a quick technique for testing the presence of salmonella.

Iowa State University researchers have developed a technique for testing the presence of salmonella.

The process, developed by Byron Brehm-Stecher, assistant professor in food science and human nutrition, and his graduate student Bledar Bisha, begins with applying a strip of adhesive tape to the food. The tape is then carefully removed, taking a sample of whatever is on the skin of the produce.

That sample is then put on a slide and soaked in a special warm, soapy mixture that contains a genetic marker that binds with salmonella and gives off a fluorescent glow when viewed under an ultraviolet light.

Use of the genetic marker approach is called Fluorescent In-Situ Hybridisation, or FISH. The approach can tell investigators if the produce is contaminated with salmonella in about two hours. Current methods of detecting salmonella take one to seven days.

Brehm-Stecher and Bisha call the process ‘tape-FISH’ and note that it could be an important technique for salmonella investigators.

‘I think this will be good tool in outbreak investigation and routine surveillance especially since all you need is tape, a heat block, a small centrifuge and a fluorescence microscope,’ said Brehm-Stecher. ‘It has the potential to be very portable.’

The tape-FISH technique can also be used to test produce that is not suspected of being contaminated, but the volume of produce that would need to be tested may make this impractical. However, the technique could be very valuable as a basic research tool, said Brehm-Stecher.

Salmonella-contaminated produce – contained in a biosafety cabinet – is tested using Brehm-Stecher and Bisha’s tape-FISH method