DNA sequencing method to improve TB diagnosis

Detecting and characterising the bacteria that cause tuberculosis (TB) could be a lot easier as researchers have developed a new diagnosis approach that relies on direct sequencing of DNA extracted from sputum (a technique called metagenomics).

"Laboratory diagnosis of TB using conventional approaches is a long drawn-out process, which takes weeks or months," said co-researcher Mark Pallen, a professor at the Warwick Medical School in Britain.

"Plus, relying on laboratory culture means using techniques that date back to the 1880s!" Pallen added.

"Metagenomics using the latest high-throughput sequencing technologies and some smart bioinformatics allows us to detect and characterise the bacteria that cause TB in a matter of a day or two," he added.

The new technique also provided the researchers key insights into bacteria's genome sequences and the lineages that they belong to.

The team detected sequences from the TB bacteria in all eight sputum samples they investigated and were able to assign the bacteria to a known lineage in seven of the samples.

Metagenomics may also help detect mixed infections caused by more than one kind of bacterium, the researchers said.

However, they stress that metagenomics is still some way from routine diagnostic use.

The study appeared in the journal PeerJ.