Heat from TB may lead to new detection method

Researchers have developed a potentially faster and cheaper method for diagnosing tuberculosis and hope to test it in Tanzania.
Culture-based methods are the standard for TB tests in the developing world, but can take almost 60 days to give a result. Molecular tests like GeneXpert are fast and accurate but have high costs and require laboratories. The new method uses a microcalorimeter to detect heat produced by Mycobacterium tuberculosis, the bacterium that causes TB, on a growth meter, Sci Dev reports.
"A cheap and fast, culture-based method could therefore decrease diagnostic time and patient treatment," Olivier Braissant a researcher at the University of Basel - Switzerland and one of the study's authors, said, according to Sci Dev. "We made our own instrument with very simple and inexpensive parts for a very low cost of US$1,000 [some rapid detection methods cost more than US$39,000] so we really believe that our method has a strong potential for places with very limited resources."
A study incorporating the new method showed that detection takes four to five days, though Braissant said that more sensitive microcalorimeters could detect tuberculosis in 24 hours.

Braissant and his team are working with the Swiss Tropical and Public Health Institute to test the method at the Ifakara Health Institute in Tanzania.
"I don't think this test has any added value as a TB diagnostic test in developing countries where microbiology culture facilities for TB are rare," Ruth McNerney, a member of the Stop TB Partnership's working group on new diagnostics, said, according to Sci Dev. "The study does not confirm the presence of bacteria, only the fact that something is growing, and you would then need to do a confirmatory test."
Braissant said that while a confirmatory test is required, microcalorimetry could determine which strains of M. tuberculosis  are drug-resistant because they would continue to grow after treatment.