The Xpert MTB/Rif test is a cartridge-based fully automated NAAT (nucleic acid amplification test) for TB
case detection and rifampicin resistance testing, suitable for use in disease-endemic countries. It
purifies, concentrates, amplifies (by rapid, real-time PCR) and identifies targeted nucleic acid sequences
in the TB genome, and provides results from unprocessed sputum samples in less than 2 hours, with
minimal hands-on technical time.
Although molecular amplification is already a proven technology in TB diagnosis, other existing test
methods are too complex for routine and widespread use in developing countries. The need for sample
processing and DNA extraction adds another level of complexity to implementation in settings where
resources are limited.
GeneXpert, the test device platform, was launched by Cepheid in 2004 and simplifies molecular testing
by fully integrating and automating the three processes (sample preparation, amplification and
detection) required for real-time PCR-based molecular testing. The Xpert MTB/RIF test is currently the
only molecular test of its kind and uses a cartridge containing all elements necessary for the reaction,
including lyophilized reagents, liquid buffers and wash solutions. Target detection and characterization is
performed in real time using a six-colour laser detection device.