Breath test for TB developed

It provides rapid information on drug resistance that takes up to six weeks using standard methods, US scientists report in the journal, Nature Communications.

The bacteria emit a unique gas signature within 10 minutes of exposure to an inhaled antibiotic in rabbits.

TB infects 8.6m people each year worldwide and kills 1.3m, second only to HIV.

Early diagnosis and treatment are a priority in the global fight against TB, according to the World Health Organization.

The new research used an inhaled form of isoniazid - an antibiotic commonly used to treat the disease - which is activated by a TB enzyme, BBC reported.

The test exploits the fact that this enzyme is unique to TB, said Dr Graham Timmins, Associate Professor at the University of New Mexico, US, who led the research.

"We realised that we could actually look at the conversion of isoniazid to its active form by monitoring one of the labelled gases that's given off during its activation," he explained.

The researchers gave a special molecularly-labelled form of isoniazid to laboratory rabbits.

In the presence of TB, labelled nitrogen gas was released from the lungs and detected by a machine called a mass spectrometer.

A positive result indicates that TB bugs are present and suggests they are susceptible to isoniazid.

TB is very difficult to treat, requiring at least six months of treatment with multiple drugs.

Failure to complete treatment has contributed to the rise of multidrug-resistant TB (MDR-TB), accounting for 30% of cases in some countries.

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