What Does GeneXpert Mean on a TB Test Report?

What it means

GeneXpert is the name of a testing machine. On TB reports, it usually refers to the Xpert MTB/RIF test, which searches a sample, most often sputum, for the DNA of Mycobacterium tuberculosis, the germ that causes TB. It can give a result within a couple of hours, much faster than growing the germ in a culture.

The report usually gives two answers. The first is whether TB germ DNA was detected ("MTB detected" or "MTB not detected"), sometimes with a level such as very low, low, medium or high. The second is whether the germ shows signs of resistance to rifampicin, one of the main TB medicines ("RIF resistance detected" or "not detected"). These answers help the TB team decide quickly whether to start treatment and which medicines to use. In India, the same test is often called CBNAAT.

GeneXpert is different from an AFB smear. A smear is a microscope check for acid-fast bacteria, while GeneXpert looks specifically for TB genetic material and can find smaller amounts.

Where you may see it

• Sputum results at TB clinics and chest clinics
• Hospital lab reports for people with a long-lasting cough, fever or weight loss
• Results on samples other than sputum, such as lymph node fluid or spinal fluid
• Referral forms and TB treatment cards