4.2.5
Xpert MTB/RIF Assay
National TB Management Guidelines, 2018 Edition. Chapter 4, Approach to TB diagnosis.
Clinical description
This assay is indicated for the diagnosis of MTB and to screen for rifampicin resistance (RR) in sputum samples. In Malawi, Xpert is recommended to diagnose TB in HIV positive, pediatric and ETB patients. Its biosafety level (BSL-2) is the same as for direct microscopy, making it feasible for peripheral laboratories.
The Xpert MTB/RIF assay simultaneously detects MTB and RR in less than 2 hours, with a sensitivity for detection that is like that of liquid culture (88% when compared with liquid culture as a standard). The superior performance of Xpert MTB/RIF in detecting TB over that of microscopy makes it a particularly useful tool for case-finding among PLHIV. As a tool for detecting RR, Xpert MTB/ RIF has a sensitivity of 95% and a specificity of 98%.
Advantages of Xpert MTB/RIF
- Allows simultaneous detection of both MTB and RR.
- High sensitivity (68%) and specificity (99%) for MTB detection even in smear negative
cases.
- Produces results in two hours.
- Minimal technical training is required to run the assay.
- Does not require sophisticated biosafety precautions.
36 National Tuberculosis Control Programme
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