New TB Meningitis test bests the rest

Tuberculous meningitis

TB meningitis is a major cause of death in Southern Africa, but the current diagnostic tests are not as quick or as sensitive as they need to be. Finding a sensitive, rapid test for TB meningitis has been elusive until now, but that is changing thanks to BioFISA II funding and researchers at Antrum Biotech.

Antrum Biotech, in partnership with the University of Cape Town, have developed a  new rapid test, able to diagnose TB meningitis within two hours. The test is currently undergoing validation to enter the global market.

The accurate diagnosis of TB meningitis represents an unmet need in public health, with problems of missed diagnosis and misdiagnosis affecting health outcomes,” says Antrum Biotech CEO Khilona Radia. “The greatest need for the test is in populations with a high burden of TB and HIV; particularly in sub-Saharan Africa where the test will be evaluated and launched. The long-term goal of this project is to reduce global TB meningitis deaths.”

Two percent of tuberculosis (TB) cases, which are caused by Mycobacterium tuberculosis, develop into an infection of the membranes around the central nervous system (meninges). This TB meningitis can cause death or disability, especially in children, but is easily treatable if diagnosed early.

The new Antrum Biotech test will compete against TB meningitis tests that either take too long to detect Mycobacterium, or are not sensitive enough to find it when it is there. The test surpasses smear microscopy and the WHO-recommended GeneXpert diagnostic in sensitivity, and since it takes less than a day to yield results, it is much more rapid than growing a culture in a lab.

“Detection under the microscope only works 5% of the time. Smear microscopy is a very poor test,” says Professor Keertan Dheda, the director of the Centre for Lung Infection and Immunity at the University of Cape Town.

“Another existing test for TB meningitis involves growing the bug in the lab in a culture, and there are problems with that too,” he says. This culture-based test has a sensitivity of only 60% to 70%, and it can take four to eight weeks to give a result. “By then most people would have died, or they would have developed severe disabilities due to the disease,” says Dheda.

The GeneXpert DNA detection test for TB is widely used in South Africa, but studies show that it is not sensitive enough to detect TB meningitis. but the test has limited sensitivity. “Although it is rapid in getting the answer on the same day, the problem is that it detects TB meningitis in only 50-60% of cases; we have a major unmet need for a more sensitive test,” says Dheda.

“Preliminary results from our studies show a vast improvement in sensitivity when compared to GeneXpert.

Funding from the BioFISA II programme has allowed researchers to develop the test further, and it is now undergoing a series of validation studies in southern African populations to pin down its sensitivity more accurately. This will include comparative sensitivity to GeneXpert.

“The funded collaboration between the University of Malawi College of Medicine, the Biomedical Research Training Institute in Zimbabwe, and Antrum Biotech was a first; this has solidified our partnerships for future research and development,” says Radia.

Antrum Biotech and its partners plan continue with validation studies even after the test goes on sale in the near future.

“There will be even larger studies and studies by different groups of people in different parts of the world to confirm the results that we found in southern Africa,” Dheda says.