At-home test checks your spit for TB

A probe lights up blue if you're infected. This quick and cheap tool could be used in remote locations where the disease is especially common.
Written by Janet Fang, Contributor

Scientists have developed a new fluorescent probe that can be used to quickly detect tuberculosis bacteria from a sputum sample -- using just a homemade LED box and a camera phone. Nature News reports.

In 2010, TB killed nearly 4,000 people a day, mostly in remote places around the world. Treatments are available, but diagnosis can take several weeks – during this time, patients can transmit the infection. (If a person with active TB goes untreated, that individual will infect up to 15 people a year, on average.)

The most common test for active TB is called the ‘sputum smear microscopy.’ That’s when your coughed-up saliva and mucus are examined under a microscope for the presence of TB bacteria (pictured). But this requires a lot of trained staff, and it can’t diagnose TB in children.

And, compared to chest X-rays or blood tests, this fluorescent molecule is a much cheaper and quicker diagnostic test, one that can be used in places that lack clinical infrastructure.

To create an efficient detection method, Stanford’s Jianghong Rao and colleagues developed a simple fluorescent molecule.

  1. In nature, a TB protein known as BlaC breaks down a particular class of chemicals called β-lactams. Here, the researchers designed their molecule to resemble a β-lactam so that it’s cut in half by BlaC.
  2. This probe is normally colorless, but when it’s cut by BlaC from TB bacteria, it releases a blue fluorescent product.
  3. And that’s detected using a homemade box containing a light-emitting diode and a couple of filters.
  4. The faint light that’s emitted can be captured by a camera phone, making it easy to share with clinicians. No microscope, no lab.

A prototype test is currently being developed by Global BioDiagnostics in Texas, with the product expected to be available by 2015.

The work was published in Nature Chemistry this week.

[Via Nature News]

Image: Mycobacterium tuberculosis / CDC via Wikimedia

This post was originally published on Smartplanet.com

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