Inexpensive test may diagnose TB in 30 minutes

Scientists are developing a portable, battery-powered device that could provide the fastest tuberculosis diagnosis yet, taking less than half an hour to detect the bacteria.
Currently, a method called GeneXpert, can accurately detect Mycobacterium tuberculosis DNA within a couple of hours, but it requires specialised equipment and trained personnel, making it impractical for rural areas or developing countries.
Chemist Jianghong Rao of Stanford and microbiologist Jeffrey Cirillo of Texas A&M Health Science Center in Bryan have developed a chemical called CDG-3, which glows when it is broken down by an M tuberculosis enzyme called BlaC.
The researchers found that they could detect as few as ten bacteria in a millilitre sample, 'nature.Com' reported.

They then tested the method on 50 sputum samples from people in Texas.
It correctly identified all the samples that contained M tuberculosis visible under a microscope, and 80 per cent of those in which infections were not visible.

When tested in people without TB, the CDG-3 probe diagnosed them correctly 73 per cent of the time.
Rao and Cirillo are now working with diagnostics company GBDbio in Temple, Texas, to develop a portable, battery-powered device that measures the fluorescence coming from CDG-3 as it is broken down.
Chief executive Michael Norman said that the company hopes to have the device completed and on the market in 2015.

He expects that a single test will cost about USD 5, and will take less than 30 minutes to deliver a diagnosis.