GENEXPERT MTB/RIF (CBNAAT)

GeneXpert MTB/RIF (CBNAAT)

What it is

The GeneXpert MTB/RIF (also known as CBNAAT – Cartridge Based Nucleic Acid Amplification Test) is a rapid molecular test used to detect Mycobacterium tuberculosis (MTB), the bacteria that causes tuberculosis (TB), and simultaneously identify resistance to rifampicin, one of the key first-line TB drugs. This test uses real-time PCR technology and provides results within 2 hours, making it far quicker than traditional culture-based methods.

Uses

This test is widely used to:

• Diagnose pulmonary and extra-pulmonary tuberculosis.
• Detect rifampicin resistance, which is a marker for multidrug-resistant TB (MDR-TB).
• Support early treatment decisions for TB patients.
• Assist in TB control programs by providing rapid, reliable results in high-burden areas.

Symptoms That May Lead to the Test

A doctor may order the GeneXpert MTB/RIF test if you present with persistent cough (more than 2 weeks), fever, night sweats, unexplained weight loss, chest pain, blood in sputum (hemoptysis), or lymph node swellings. It is also recommended for individuals with HIV or those in close contact with TB patients.

Abnormal Results

MTB Detected with Rifampicin Sensitivity: Confirms TB infection but no rifampicin resistance, suggesting drug-sensitive TB.

MTB Detected with Rifampicin Resistance: Indicates drug-resistant TB (MDR-TB), requiring special treatment regimens.

MTB Not Detected: Suggests absence of TB. However, if clinical suspicion is high, further testing such as culture or imaging may be required.

Risks

The risks are limited to the sample collection process. For sputum, there are no risks apart from minor discomfort. In cases where other body fluids or tissue are sampled (e.g., cerebrospinal fluid, pus, lymph node aspirate), there may be minimal discomfort, pain, or risk of infection at the collection site.