GeneXpert MTB/RIF

GeneXpert MTB/RIF is a molecular testing method that identifies the Mycobacterium tuberculosis bacteria and resistance to rifampin, a key tuberculosis drug. The test is automated and can be performed by general health workers with minimal training. It provides results in less than two hours.

Overview

The GeneXpert System is a closed, self-contained, fully-integrated and automated platform that represents a paradigm shift in the automation of molecular analysis, producing accurate results in a timely manner with minimal risk of contamination. The GeneXpert System is the only system to combine on-board sample preparation with real-time PCR (polymerase chain reaction) amplification and detection functions for fully integrated and automated nucleic acid analysis. The system is designed to purify, concentrate, detect, and identify targeted nucleic acid sequences thereby delivering answers directly from unprocessed samples.

Use in Tuberculosis Diagnosis

The GeneXpert MTB/RIF test is a nucleic acid amplification test (NAAT) for the detection of Mycobacterium tuberculosis complex DNA and the rpoB gene associated with rifampin resistance. The test is performed on the GeneXpert Instrument Systems. The test is intended for use with specimens from patients for whom there is suspicion of pulmonary tuberculosis and who are either smear-positive or risk factors for rifampin resistance.

Advantages

The GeneXpert MTB/RIF test has several advantages over traditional methods of testing for tuberculosis. It is faster, with results available in less than two hours, compared to weeks for culture-based methods. It is also more sensitive than smear microscopy, particularly in patients with HIV co-infection or in children. The test can also detect rifampin resistance, which is an indicator of multidrug-resistant tuberculosis.

Limitations

While the GeneXpert MTB/RIF test has many advantages, it also has some limitations. It is more expensive than smear microscopy and requires a stable electricity supply and annual calibration of the machine. It also cannot differentiate between live and dead bacteria, so it may give positive results in patients who have been successfully treated for tuberculosis.

See Also

• Tuberculosis
• Mycobacterium tuberculosis
• Rifampin
• Multidrug-resistant tuberculosis