Rapid test 'may change the face of medicine'
By Roger Highfield, Science Editor
The first DNA-based test that can diagnose a range of diseases within 30 minutes is to go on trial in British hospitals.The test could change the face of general practice and veterinary medicine. Rapid diagnosis could help GPs to prescribe antibiotics only when necessary by revealing if a sore throat is caused by a virus or bacterium, and cut the inappropriate use of antibiotics, which drives the rise of superbugs.
The DNA test can quickly pin down the cause of food poisoning, help farmers detect foot and mouth, and show if a woman is a carrier of the bacterium that causes chlamydia, a "silent disease" that can cause fertility problems.
The portable mini-lab is a spin-off from biological warfare research and works by hunting for the DNA of target organisms, said Dr David Squirrell, one of the developers at the Defence Science and Technology Laboratory, Dstl, Porton Down.
The team bases the test on the PCR (polymerase chain reaction) process, which amplifies target DNA, a method that won Dr Kary Mullis the Nobel prize.
Yesterday, speaking at a conference in Bournemouth, Dr Mullis said tests based on the method had huge potential because "you need to know what a disease is before you can do anything about it".
At first, Porton Down wanted to find a way to use PCR for fast battlefield detectors of biological warfare agents such as anthrax but its wider potential was realised and Dstl has launched a joint venture with industry, called Enigma Diagnostics.
The tests will offer GPs and vets much faster results than currently possible and they could eventually cost less than £10 each.
The team plans to provide two rapid, automated PCR machines for various uses.
The first trials, at hospitals in Portsmouth and Liverpool, will be in using urine samples to diagnose infections, notably chlamydia, within 40 minutes.
At present chlamydia testing requires samples to be sent away for analysis and it can take up to two weeks to get the results back.
Trials of the "while you wait" test, backed by the Department of Health and called NPTGold, will be used in genito-urinary clinics by the end of the year.
There will also be quick-testing at GP surgeries and clinics to give correct and effective prescription of medicines.
The test will be used to detect genetic modifications in food and spot contamination by organisms such as salmonella, listeria and E.coli.
There will also be in-the-field testing for animal diseases, including foot and mouth or tuberculosis in cattle within 30 minutes, rather than having to send samples to a lab.
Tim Rubidge, Dstl head of technology transfer and investments group, said the idea of a tabletop DNA test laboratory was no longer a "a twinkle in the eye of a research scientist looking far out into the future".
"We have a portfolio of more than 20 strong patents, field-tested instruments and continuing research projects supporting the MoD and Department of Health," he said. "It is fair to say that we have taken PCR out of the research lab and into the field where it is most needed."
The heart of the device relies on polymerase chain reaction, which heats and cools samples using an enzyme from a heat-tolerant bacterium to generate billions of copies of segments of DNA from a sample.
It is normally a laboratory-based technique. The Porton team uses custom-built test tubes made from a novel, electrically-conducting polymer to heat and cool samples. This not only speeds up the process, but also creates a lighter, more portable instrument