A simple experimental blood test appears to accurately diagnose tuberculosis among patients with varying degrees of exposure to the disease, a leading cause of death worldwide, researchers reported on Tuesday.
TB is typically diagnosed by analyzing mucus secretions coughed up from the lungs and airways.
“However, not all patients can produce sputum when they first seek medical care, especially those with early disease or those with low bacterial burden,” study leader Dr. Sheng-Wei Pan of Taipei Veterans General Hospital in Taiwan said in a statement.
“For that reason, non-sputum-based diagnostic tools are urgently needed,” he said.
TB is almost always curable with antibiotic therapy when the M. tuberculosis bacteria is detected in the initial stages of the disease, the researchers noted.
Using a newly designed biosensor, researchers were able to sensitively detect a blood marker produced by the bacteria called ESAT-6, they reported at the Association for Diagnostics & Laboratory Medicine meeting in Anaheim, California.
While ESAT-6 has been studied before, most earlier sensors used to detect it have not been sensitive enough to distinguish active pulmonary TB from latent TB infection, TB exposure, or other lung diseases.
The ESAT-6 marker did an excellent job of differentiating between TB- and non-TB patients, the researchers said.
They saw the lowest levels in uninfected people who had been exposed to infected contacts, medium amounts in those with latent tuberculosis, and the highest levels in patients with active TB.
Unlike biomarkers that measure the body's immune response to infection, ESAT-6 is derived directly from the TB bacteria.
“We believe this is one reason why it performs so well in identifying active TB,” Dr. Pan said.
“We are currently planning a prospective study to further evaluate if this can be used in a real-world clinical setting,” he said.
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