A TEST that can detect as few as 100 dangerous bacteria in just 15 minutes
has been developed by researchers in Utah. The existing commercial tests take at
least a day.
The test could be used to detect bacteria such as the O157:H7 strain of
E. coli, which causes 20,000 cases of severe food poisoning a year and can
be fatal. It could also pick up other food-poisoning bugs such as Listeria
or Salmonella. Developed by Bart Weimer and his colleagues
at Utah State University in Logan, the sensor uses antibodies attached to a bed
of glass beads. The antibodies bind to specific bacteria in samples of food or
water passing over the beads. Light-emitting chemicals are then used to detect
any bound bacteria.
A high flow rate is vital, says Weimer. It not only brings the bacteria into
contact with the antibodies on the beads, but also prevents the beads getting
clogged by material in the sample such as hamburger meat. The method is so
sensitive samples can be tested directly. In contrast, existing commercial
methods require any bacteria present to be cultured for at least a day before
there are enough to detect. The researchers say that in tests on samples such as
hamburgers, apple juice, beer and bean sprouts, the new system sometimes spotted
bacteria that commercial tests missed.
Advertisement
The latest automated version of the test takes as little as 15 minutes.
鈥淭hat鈥檚 sub real-time for a microbiologist,鈥� says Weimer. In this version, the
beads are housed in a disposable cartridge that is inserted into an instrument
that reads off the results. The technology has been licensed to Stellar
Technologies of Boise, Idaho, which hopes to have a commercial version available
next year.