Three new diagnostic tests may provide faster TB diagnoses
Current methods of TB diagnosis require a sputum sample that must be collected then cultured. The test typically takes between 21 days and three months to complete. A faster diagnosis improves a patient's chances of survival and helps prevent the development of drug-resistant TB or extremely-drug-resistant TB.
A new study developed three new diagnostic tests and tested their effectiveness. The tests were a pyrosequencing test using a DNA sequencing method, the HAIN line probe test that can identify genetic mutations in bacteria and the microscopic observation drug susceptibility test, which observes samples underneath a microscope.
More than 1,000 patients in India, Moldova and South Africa were tested during the study. Traditional and experimental methods were used to test for drug resistance to isoniazid, moxifloxacin, rifampin, Capreomycin, amikacin and kanamycin. The results found that the MODS test was complete in 15 days, pyrosequencing took 8 days and the line probe took 5 days to complete at 95-98 percent efficacy.
"Our findings suggest these three tests could provide a quicker way to identify patients who need alternative treatment regimens," Professor Antionino Catanzaro from the University of California, San Diego, said. "This is very important and could potentially save lives as well as help to curb the rise of drug resistant TB. There are benefits and disadvantages to each test. For example, the MODS test, although the slowest of the three new tests we looked at, is much cheaper. It is important to have this range of options available so that TB treatment programmes across the world can assess which method is right for them including consideration of the financial restrictions they work within."