The Xpert MTB/RIF is a cartridge-based, automated diagnostic test that can identify Mycobacterium tuberculosis (MTB) and resistance to rifampicin (RIF). It was co-developed by Cepheid, Inc. and Foundation for Innovative New Diagnostics, with additional financial support from the US National Institutes of Health (NIH) and technical support from the University of Medicine and Dentistry of New Jersey (UMDNJ).[1]
In December 2010, WHO endorsed the automated NAAT for use in TB endemic countries and declared it a major milestone for global TB diagnosis. This follows 18 months of rigorous assessment of its field effectiveness in TB, MDR-TB and TB/HIV co-infection.[2][3] This test, and others that are likely to follow, have the potential to revolutionize the diagnosis of TB.[4][5]
Contents |
Tuberculosis is one of the deadliest public health threats today, but there remains a lack of effective diagnostic tools. According to the WHO, only 5 percent of the estimated global burden of multi-drug-resistant tuberculosis (MDR-TB) are detected due to critical gaps in laboratory capacity in many endemic countries.[6] This contributes to the global TB problem, as untreated TB patients remain a source of infection for other members of the community. Untreated TB also results in considerable morbidity and mortality, especially in HIV co-infected individuals.[7]
The most widely used method for tuberculosis diagnosis in most disease-endemic countries is the 125 year-old sputum smear microscopy test, which has a number of drawbacks including low sensitivity (especially in HIV-positive individuals and children), inability to determine drug-susceptibility, and variable performance that depends on the expertise of the microscopist.[8]
The Xpert MTB/RIF is based on the Cepheid GeneXpert platform, a highly sensitive, rapid and simple-to-use nucleic acid amplification test (NAAT).[9] The Xpert® MTB/RIF purifies, concentrates, amplifies (by real-time PCR) and identifies targeted nucleic acid sequences in the TB genome, and provides results from unprocessed sputum samples in 90 minutes, with minimal biohazard and very little technical training required to operate.[10][11]
Some concerns have been raised about the Xpert MTB/RIF, including minor operational issues and cost.[12][13]
A major potential problem with widespread use of GeneXpert system is that there is no alternative, there is no other technologies that can do genes amplification and detection on a "as-needed" basis, on this aspect Xpert system is revolutionary. If public health authorities are to recommend use then it would mean a huge market for Cepheid.