CRISPR-based TB test could simplify screening

A CRISPR-based tongue swab test has been developed to diagnose of tuberculosis (TB) infections.

Researchers from Tulane University, New Orleans, Louisiana, have used CRISPR/Cas9 to develop a 'one-pot' tongue swab test to screen for TB. The test uses existing CRISPR technologies to rapidly amplify low amounts of bacterial DNA to return test results in one hour, similar to a COVID-19 rapid test.

'Tongue swabs are painless, easy to collect, and don't require trained medical staff,' said Dr Zhen Huang, senior author of the study published in Nature Communications.

The new test showed a 74 percent detection rate compared to 56 percent from standard TB tests, which use sputum (mucus) from lungs to diagnose infections.

The study aimed at developing a lateral-flow-like test for detecting TB in low-resource communities, since high TB burden is associated with increased poverty. Collecting sputum and conducting tests requires expensive infrastructure that is not feasible in some areas. Sputum testing is also impossible in about 25 percent of cases, and as up to 90 percent of infected people are asymptomatic, many remain undetected and untreated.

'More than ten million people worldwide fall ill with tuberculosis every year, but 40 percent of those cases are considered missing as people go undiagnosed,' said Dr Tony Hu, senior corresponding author of this study. 'To find those missing cases, testing needs to be less invasive and more accessible to reach as many people as possible who may not otherwise be tested.'

The test also showed higher sensitivity in detecting TB from adult respiratory (93 percent), paediatric stool (83 percent) and adult cerebral spinal fluid samples (93 percent).

The researchers highlight the need for future studies to validate their findings in larger studies. They also observed that different methods of swab collection and storage of CRISPR reagents have an impact on the performance of the test. Therefore, standardised approaches for swab collection and storage of test reagents need to be developed.

'If we want to end TB, we need tools that work outside the lab and in the communities where the disease spreads,' added Dr Hu.