In a far-reaching discovery that will help millions of tuberculosis patients, scientists have developed a TB test which they say is faster, cheaper and more accurate and also identifies multi-drug resistance.
At present, the World Health Organization recommends the sputum-smear microscopy test, which analyses the material expelled from the lungs by a deep cough.
However, the test, though fast, is not accurate in around 50 percent of cases, and it can take up to six weeks to culture the sample, confirm the results and determine whether it is resistant to drugs. These detailed checks are only rarely available in the developing world.
The new test, developed by British, US and Peruvian researchers, is named as microscopic-observation drug-susceptibility (MODS) test. It allows doctors to diagnose TB twice as quickly as previous gold-standard culture tests and to identify multi-drug resistance in a third of the time, reported the online edition of BBC News.
In tests on nearly 4,000 sputum samples MODS identified TB with 97.8 percent accuracy - significantly out-performing the current tests.
The new test works by culturing the TB organism in a liquid, rather than the traditional solid substance. This enables it to grow more rapidly, and for scientists to detect its characteristic pattern of tangles or coils under a microscope relatively easily.
The liquid media also means TB drugs can be more easily administered for testing. If the bacteria grow in the presence of these drugs, this indicates resistance.
The MODS test is also cheaper and more sensitive to drug resistant strains than current tests. It yields results in an average of seven days, and could help save many lives, the researchers said.
The new test offers the best hope of a quick diagnosis for the 50 percent of people in the developing world who are not detected by the current test, an expert said. Details of the test appear in the New England Journal of Medicine.