The new test that works quickly and in places with few of the amenities - even seemingly basic ones like refrigeration - has been developed by the researchers at Stanford University. Tuberculosis (lat. Phthisis), a distant memory to most Americans, remains a serious public health threat in developing countries, in part because the most common test for the disease was developed a century ago and is not the most reliable. Now, a team of basic chemists working in collaboration with doctors and public health researchers in South Africa has developed a new test that makes it easier to diagnose and therefore treat the disease. Professor Carolyn Bertozzi and her lab have been studying tuberculosis for 20 years. Among their most important discoveries was that of a special sugar molecule, called trehalose, that only living tuberculosis bacteria consume and that other bacteria eschew.
The goal back then was mainly to understand how tuberculosis worked, but over time she realized her results might have clinical significance as well. What those people needed, in other words, was a test that was fast, cheap and good. The researchers accomplished all three with a solution based on what they’d learned previously about the tuberculosis bacteria’s penchant for trehalose. They attached the sugar to a fluorescent dye that, once ingested, glows about 700 times brighter than before: Spot a very bright cell, and live tuberculosis must be present.
The test, called DMN-Tre, takes just a few steps and produces results in under an hour. Because of the test’s speed, doctors may be able to test antibiotics against sputum samples to quickly find the right antibiotics for the particular strain a patient carries. Still, the real test comes not in the lab but out in the real world with real patients. For that, the researchers turned to collaborator Bavesh Kana and his team at the University of Witwatersrand in Johannesburg, South Africa. They conducted tests on 40 tuberculosis patients who had not yet been treated for the disease. DMN-Tre, the researchers found, performed as well as existing tests that took more steps to complete.
Another important test will be seeing whether they can accurately track the decline of tuberculosis bacteria in drug-treated patients, which will take much longer. Those bacteria, she said, can take three months or more to clear out of a patient’s system, so it will be important to assess whether DMN-Tre can help quickly determine drug efficacy during patient treatment in rural areas.
The work so far has already opened up a number of new possibilities. Other researchers in South Africa are looking at whether it could help diagnose TB in patients with HIV, for whom standard sputum tests often do not work. DMN-Tre could also help researchers trying to understand how tuberculosis circulates in rooms and buildings. There is a lot about the life cycle of tuberculosis that people don’t understand, and it’s hard to study. This tool could be an enabling reagent for a variety of tuberculosis-related research projects.