Three new rapid tests can significantly cut the time for accurate detection of extremely drug resistant tuberculosis (XDR-TB), according to an abstract presented at the European Respiratory Society’s Annual Congress (Barcelona, Spain; Sept. 8-11). The National Institutes of Health-funded Global Consortium for Drug-Resistant TB Diagnostics studied rapid drug susceptibility tests at clinical sites in India, Moldova, and South Africa with the goal of reducing XDR-TB detection time to a week (compared to the 21 days to three months that traditional methods of drug-susceptibility testing can take) and ascertaining the level of agreement between rapid tests and standard drug susceptibility tests for five drugs with known resistance. The three new tests evaluated were pyrosequencing, a DNA sequencing technique; the HAIN line probe test (Hain Lifescience; Germany), a commercial test that detects genetic mutations in the bacteria; and the microscopic observation drug susceptibility (MODS) test, which screens samples using a microscope. Based on samples from 1,000 participants, the researchers found that all tests were more rapid than traditional methods with MODS taking 15 days to complete, pyrosequencing taking eight days, and the line probe assay taking five days. All three tests produced highly concordant results to standard testing, ranging from 95 percent […]
Three new rapid tests can significantly cut the time for accurate detection of extremely drug resistant tuberculosis (XDR-TB), according to an abstract presented at the European Respiratory Society’s Annual Congress (Barcelona, Spain; Sept. 8-11).
The National Institutes of Health-funded Global Consortium for Drug-Resistant TB Diagnostics studied rapid drug susceptibility tests at clinical sites in India, Moldova, and South Africa with the goal of reducing XDR-TB detection time to a week (compared to the 21 days to three months that traditional methods of drug-susceptibility testing can take) and ascertaining the level of agreement between rapid tests and standard drug susceptibility tests for five drugs with known resistance. The three new tests evaluated were pyrosequencing, a DNA sequencing technique; the HAIN line probe test (Hain Lifescience; Germany), a commercial test that detects genetic mutations in the bacteria; and the microscopic observation drug susceptibility (MODS) test, which screens samples using a microscope.
Based on samples from 1,000 participants, the researchers found that all tests were more rapid than traditional methods with MODS taking 15 days to complete, pyrosequencing taking eight days, and the line probe assay taking five days. All three tests produced highly concordant results to standard testing, ranging from 95 percent to 98 percent for all of the tested drugs. There are trade-offs with the tests, the researchers say. For example MODS is the slowest, but it is also the cheapest of the tests examined.
“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,” says lead author, Antonino Catanzaro, M.D., from the University California, San Diego in a statement. “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.”
Takeaway: Three new tests—pyrosequencing, molecular line probe testing, and MODS—are each accurate and substantially cut the time to results for detecting XDR-TB compared to traditional testing methods. This expanded range of testing options can benefit TB treatment programs across the world.
