A new molecular test for tuberculosis can diagnose TB and detect a drug-resistant form of it far more easily and rapidly than other tests currently available.
A new molecular test for tuberculosis can diagnose TB and detect a drug-resistant form of it far more easily and rapidly than other tests currently available.
Global control of tuberculosis is hampered by slow, insensitive diagnostic methods, particularly for the detection of drug-resistant forms and in patients with human immunodeficiency virus infection. Doctors say current diagnostic testing for TB, which involves microscopy in labs with trained experts and can take weeks, has barely been improved in the last 125 years.
TB afflicts mostly the poor in developing regions such as sub-Saharan Africa, India and China, but also occurs in poor regions of developed nations and is common in patients with the HIV virus that causes AIDS. It is among the world's top 10 leading causes of death. Tests for drug-resistant TB can take months and are notoriously insensitive, so new, more accurate tools to rapidly diagnose TB and its drug-resistant forms are urgently needed.
To assess the performance of Xpert MTB/RIF, an automated molecular test for Mycobacterium tuberculosis (MTB) and resistance to rifampin (RIF), researchers studied 1730 patients with suspected drug-sensitive or multidrug-resistant pulmonary tuberculosis from six countries. Three sputum specimens were taken from all the participants. Two specimens were processed with N-acetyl-L-cysteine and sodium hydroxide before microscopy, solid and liquid culture, and the MTB/RIF test, and one specimen was used for direct testing with microscopy and the MTB/RIF test.
It was found the Xpert MTB/RIF test successfully identified 98 percent of all cases and also identified patients with a form of TB resistant to rifampin, or rifampicin - one of the most powerful TB drugs - and achieved these results in less than two hours.
The study shows that within two hours, you can not only have a diagnosis, but you can also have a good idea of the range of drugs you can use. Limitations of this study include a possible lack of generalizability to settings with less controlled conditions, and the high costs of the manufacturing technology needed for the MTB/RIF test.
Global control of tuberculosis is hampered by slow, insensitive diagnostic methods, particularly for the detection of drug-resistant forms and in patients with human immunodeficiency virus infection. Doctors say current diagnostic testing for TB, which involves microscopy in labs with trained experts and can take weeks, has barely been improved in the last 125 years.
TB afflicts mostly the poor in developing regions such as sub-Saharan Africa, India and China, but also occurs in poor regions of developed nations and is common in patients with the HIV virus that causes AIDS. It is among the world's top 10 leading causes of death. Tests for drug-resistant TB can take months and are notoriously insensitive, so new, more accurate tools to rapidly diagnose TB and its drug-resistant forms are urgently needed.
To assess the performance of Xpert MTB/RIF, an automated molecular test for Mycobacterium tuberculosis (MTB) and resistance to rifampin (RIF), researchers studied 1730 patients with suspected drug-sensitive or multidrug-resistant pulmonary tuberculosis from six countries. Three sputum specimens were taken from all the participants. Two specimens were processed with N-acetyl-L-cysteine and sodium hydroxide before microscopy, solid and liquid culture, and the MTB/RIF test, and one specimen was used for direct testing with microscopy and the MTB/RIF test.
It was found the Xpert MTB/RIF test successfully identified 98 percent of all cases and also identified patients with a form of TB resistant to rifampin, or rifampicin - one of the most powerful TB drugs - and achieved these results in less than two hours.
The study shows that within two hours, you can not only have a diagnosis, but you can also have a good idea of the range of drugs you can use. Limitations of this study include a possible lack of generalizability to settings with less controlled conditions, and the high costs of the manufacturing technology needed for the MTB/RIF test.
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