Early diagnosis of tuberculosis is now a step closer, say scientists from India and Japan.

The disease-causing bacterium M. tuberculosis can be detected in about 12 minutes © Centers for Disease Control and Prevention (CDC)

Bansi Malhotra from the National Physical Laboratory in New Delhi, India and colleagues have made a detection device that is quick, precise and efficient to use.

According to the World Health Organization, tuberculosis kills nearly three million people every year. Patients suffer damage to their lungs, bones and central nervous system. Current detection techniques, such as the polymerase chain reaction (PCR) and immunoassays, although sensitive, can take from hours to days to complete and are expensive. A faster and cheaper test is an absolute necessity, says Malhotra.

Malhotra's sensor detects the DNA of the disease-causing bacterium Mycobacterium tuberculosis. When a serum sample containing the bacterium passes over the sensor, the bacterial DNA binds to complementary nucleotide sequences fixed to a gold surface. This causes a change in optical properties which can be detected using surface plasmon resonance.

The device was so sensitive, it could detect M. tuberculosis DNA without PCR amplification or rigorous washing, decreasing the detection time to around 12 minutes. Malhotra says that the next step is to make a commercial sensor for clinical samples and miniaturise it for point-of-care use. But the research doesn't stop there: 'This technique has implications for the diagnosis of other diseases, such as cholera, and sexually transmitted infections like Neisseria gonorrhoeae,' he explains.

Rebecca Brodie