Medical Xpress (09.08.2013)
Aids Weekly Plus
A study, presented this week at the European Respiratory Society's Annual Congress in Barcelona, Spain, unveiled three new tests that could diagnose drug-resistant TB in a much shorter timeframe than the current standard test, but with the same precision. Early and accurate identification of drugs to which TB bacteria are sensitive or resistant is critical in providing the quickest cure to the patient as well as in warding off developing more drug-resistant TB, especially for patients with extremely drug-resistant TB, who might have a short life expectancy if not treated properly.
The current test collects and cultures a sputum specimen and could take between 21 days to three months for results. The three new tests took between five to 15 days. The testing timeframe showed: the microscopic observation drug susceptibility (MODS) test took 15 days to complete; pyrosequencing, a DNA sequencing technique, took eight days to complete; and the HAIN line probe assay took five days. All three tests produced the same results as the standard testing 95–98 percent of the time for almost all the drugs.
"Our findings suggest these three tests could provide a quicker way to identify patients who need alternative treatment regimens. This is very important and could potentially save lives as well as help to curb the rise of drug-resistant TB,” said Antonino Catanzaro, a professor at the University California, San Diego. He added that each new test had benefits and disadvantages. For example, the MODS test, which was the slowest of the three tests, cost much less. “It is important to have this range of options available so that TB treatment programs across the world can assess which method is right for them, including consideration of the financial restrictions they work within," he said.
Researchers selected more than 1,000 patients in India, Moldova, and South Africa to investigate effectiveness of the new tests. For each participant, researchers used the three new tests as well as the standard test to evaluate drug resistance to five drugs: isoniazid, rifampin, moxifloxacin, ofloxacin, amikacin, capreomycin, and kanamycin.