New automated test can diagnose tuberculosis in less than two hours
A new rapid automated molecular test system (Xpert MTB/RIF) can detect TB and find out whether it is resistant to the drug rifampicin in less than two hours. The system needs minimal hands-on time and can be operated by relatively unskilled workers without laboratory facilities. Its development was supported by the Foundation for Innovative New Diagnostics (FIND), Geneva and the University of Medicine and Dentistry of New Jersey in collaboration with a commercial partner, Cepheid.
The test system results on sputum specimens from 1462 people from Peru, Azerbaijan, South Africa and India with symptoms suggestive of active TB of the respiratory tract were reported in the New England Journal of Medicine on 9 September 2010. The investigation was funded by FIND, the National Institutes of Health, Cepheid and the Bill and Melinda Gates Foundation. The test results were compared with the microscope examination of sputum smears and with sputum cultures as the “gold standard”. The new test correctly identified 98.2% of 561 smear and culture positive subjects and 99.2% of 609 who were smear and culture negative. Of those smear negative but culture positive, three repeated tests identified 90.2%. The test correctly identified 97.6% of rifampicin-resistant and 98.1% of rifampicin-sensitive TB.
The researchers believe that the simplicity and safety of the system could allow for cost-effective and highly sensitive detection of TB and drug resistance outside reference centres. Increased access would decrease delays in diagnosis without the need to build large numbers of laboratories equipped for advanced protection of lab staff from infection.