Finding the right tests…
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Emergency services available 24 x 7
Finding the right tests…
Molecular
GeneXpert MTB is a cartridge-based PCR test that detects Mycobacterium tuberculosis DNA and screens for mutations linked to rifampicin resistance in the same run, using a closed system that needs minimal hands-on lab work. Your sputum sample goes directly into a single-use cartridge, where the machine handles processing, amplification, and detection without a technician manually transferring the sample between steps. The World Health Organization has endorsed this test since 2010 as the preferred initial test for people at risk of drug-resistant or HIV-associated TB, and it also picks up cases that smear microscopy, which needs a higher bacterial load to detect anything, can miss. Rifampicin resistance matters because it's a strong marker for multidrug-resistant TB overall.
This test reports two separate results from one sample: whether M. tuberculosis DNA was detected, and if so, whether rifampicin resistance mutations were also detected. TB detected with rifampicin resistance not detected means standard first-line treatment is likely to work. TB detected with rifampicin resistance detected raises concern for multidrug-resistant TB and usually prompts further testing, including the extended XDR panel, to guide treatment. TB not detected means the test didn't find M. tuberculosis DNA in your sample, though a very low bacterial load can still occasionally cause a false negative.
The cartridge holds all the reagents needed to break open mycobacterial cells, extract DNA, and run PCR amplification in a sealed, single-use unit. This design cuts out most of the manual handling that can introduce contamination or human error in older TB tests, and it's part of why results don't depend on a highly specialised lab.
Rifampicin resistance is closely linked to multidrug-resistant TB as a whole, since the same bacterial changes that cause it often travel alongside resistance to isoniazid, the other cornerstone first-line drug. Detecting it in the same run as TB itself means your doctor can flag a likely drug-resistant case immediately, rather than waiting for a separate resistance test.
The World Health Organization recommends this test over conventional smear microscopy as the initial test for anyone at risk of drug-resistant TB or living with HIV, since it detects more true cases, including many that smear microscopy misses because it needs a higher concentration of bacteria to show anything.
A rifampicin-resistant result doesn't tell your doctor whether the bacteria also resist other TB drugs, such as isoniazid, fluoroquinolones, or the injectable second-line drugs. That's why a rifampicin-resistant result commonly leads to a follow-on test built specifically to check those additional drugs.
This test detects genetic material directly rather than waiting for bacteria to grow, so it returns an answer well before a culture-based test, which needs the organism to multiply to detectable levels first. Ask your doctor or the centre about what to expect for your specific case.
This standard test checks only for rifampicin resistance, while the XDR version adds isoniazid, fluoroquinolones, and other second-line drug resistance markers. Doctors typically order the XDR panel as a follow-up once rifampicin resistance is found on this test.
Not completely. A very low bacterial load in the sample can occasionally cause a false negative, so your doctor may still pursue further testing, including culture, if TB is strongly suspected despite a negative result.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Rifampicin resistance is a strong marker for multidrug-resistant TB as a whole, so checking it in the same test as the TB diagnosis lets your doctor flag a likely drug-resistant case right away instead of waiting for a separate test.
Cartridge-based PCR platforms like this one can process several specimen types, including some non-sputum samples, depending on what your doctor is investigating. Ask your doctor or the centre which sample type applies to your situation.
It generally detects more true TB cases than smear microscopy, including some that smear microscopy misses because it needs a higher concentration of bacteria to produce a visible result. That's part of why health authorities recommend it as an initial test in higher-risk situations.