GeneXpert MTB Culture (MTB Culture) Test
About GeneXpert MTB Culture (MTB Culture) Test
| Field | Value |
|---|---|
| Also Known As | GeneXpert + MTB Culture, CBNAAT with AFB Culture, Xpert MTB/RIF with TB Culture, TB Comprehensive Panel, CBNAAT and Liquid Culture Combo |
| Sample Type | Sputum (pulmonary) or extrapulmonary samples (pleural fluid, CSF, lymph node aspirate, gastric lavage, urine, pus) |
| Fasting Required | No fasting required |
| Report Time | GeneXpert: approximately 2 hours; MTB Culture: 2 to 6 weeks (liquid culture typically 10 to 21 days for positive results) |
| Recommended For | All genders and ages; particularly those with suspected active tuberculosis |
| Price | Starting at ₹2,200 |
What is a GeneXpert MTB Culture (MTB Culture) Test?
The GeneXpert MTB culture test is a combined diagnostic panel that uses two methods to detect tuberculosis (TB) in a patient sample. The first part, the GeneXpert + MTB culture (also called CBNAAT), produces rapid molecular results, while the second part grows bacteria in the laboratory to confirm the finding and check which medicines will work against it.
It is also known as the TB comprehensive panel or CBNAAT with AFB culture. Sputum is the most common sample used, though other body fluids may also be tested depending on the suspected site of infection.
What Does a GeneXpert MTB Culture (MTB Culture) Test Measure?
This panel combines two distinct tests, each providing different but complementary information. The table below summarises what each component analyses.
| Component | What It Does |
|---|---|
| GeneXpert MTB/RIF (CBNAAT) | Detects genetic material (DNA) of the tuberculosis bacterium and identifies resistance to rifampicin, a key anti-TB medicine |
| MTB Culture (Liquid/MGIT) | Grows the bacteria from the sample to confirm TB and tests its response to multiple anti-TB medicines (drug susceptibility testing) |
The CBNAAT and liquid culture combo approach is valuable because the molecular test gives fast answers, while the culture provides a complete picture of drug resistance.
Why is a GeneXpert MTB Culture (MTB Culture) Test Done?
A doctor may order the Xpert MTB/RIF with TB culture when a patient shows signs that suggest tuberculosis, or when a confirmed TB patient needs treatment monitoring.
Common Symptoms That May Require This Test
The following symptoms are among the most common reasons a doctor may request this test:
- A persistent cough lasting three weeks or longer
- Coughing up blood or blood-stained sputum (haemoptysis)
- Chest pain or discomfort when breathing
- Unexplained weight loss and loss of appetite
- Drenching night sweats
- Ongoing low-grade fever
- Persistent fatigue without a clear cause
Conditions This Test Can Help Detect
This panel can help identify several TB-related conditions. The following are key among them:
- Active pulmonary tuberculosis (TB affecting the lungs)
- Extrapulmonary tuberculosis (TB affecting lymph nodes, the brain, spine, kidneys, or the lining around the lungs)
- Smear-negative TB, where standard microscopy has failed to detect bacteria
- Rifampicin-resistant TB, which is a marker for multidrug-resistant TB (MDR-TB)
- Drug-resistant TB strains requiring specialised treatment planning
GeneXpert MTB Culture (MTB Culture) for Chronic Disease Monitoring
This test plays an important role in tracking treatment response in patients already diagnosed with TB, particularly those with MDR-TB. Conversion of the sputum culture from positive to negative is one of the most reliable signs that treatment is working. Monthly culture monitoring is recommended for MDR-TB patients to detect treatment failure at the earliest opportunity.
The GeneXpert component, however, is not suitable for monitoring treatment progress; only the culture result should be used for this purpose.
How to Prepare and What to Expect
Collecting a good quality sample is the most important part of preparation for this test.
Do You Need to Fast?
No fasting is required for this test. However, for sputum collection specifically, avoid eating, drinking, or brushing your teeth for at least one hour before providing the sample, as this helps keep the specimen free from contamination.
Practical Tips Before Your Test
The following steps will help ensure the best possible sample quality:
- Collect sputum early in the morning, when bacterial counts are typically highest
- Take a deep breath and cough from deep within the chest, not from the throat
- Continue collecting early-morning samples on three consecutive days if advised by your doctor
- Inform your doctor about any antibiotics or medicines you are currently taking
Note: While deep-lung sputum can easily be collected at home, all extrapulmonary fluid samples (such as cerebrospinal fluid, pleural fluid, or lymph node aspirates) require a specialised, sterile invasive procedure and must be collected by a healthcare professional at the diagnostic centre.
Step-by-Step Procedure
- You are given a sterile, wide-mouthed container with a secure lid for sputum collection.
- You take a slow, deep breath, hold it briefly, and then cough firmly from deep within your lungs to produce sputum (at least 2 to 5 ml is needed).
- The sputum is deposited directly into the container, taking care to avoid mixing it with saliva.
- For the GeneXpert part, the sputum is mixed with a special reagent and loaded into a single-use cartridge that the machine reads automatically.
- For the culture part, the same sample is processed and placed into a liquid growth medium (the MGIT system) and observed over several weeks for bacterial growth.
- The sealed sample is stored in a cool environment and transported to the laboratory promptly.
Factors That Can Affect Accuracy
Several factors may influence the reliability of results. These include:
- Poor sample quality (saliva instead of deep-lung sputum)
- Sample volume below 5 ml, which can reduce the chance of detecting bacteria
- Recent use of antibiotics before sample collection
- Delays in transporting the sample to the laboratory without proper cooling
- Contamination of the specimen during collection
Understanding Your GeneXpert MTB Culture (MTB Culture) Test Results
Results from this panel should always be reviewed alongside a doctor, who will consider your symptoms, medical history, and any imaging findings before drawing conclusions.
| Parameter | Normal / Expected Result | What It Means |
|---|---|---|
| GeneXpert MTB | MTB NOT DETECTED | No TB bacterial DNA found in the sample |
| GeneXpert Rifampicin Resistance | NOT DETECTED (reported only if MTB is positive) | TB bacteria are sensitive to rifampicin |
| MTB Culture | NO GROWTH / NEGATIVE | No tuberculosis bacteria grew after the full incubation period |
These are diagnostic outcomes. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain health conditions can affect how this test performs or how results should be read.
- People living with HIV have a higher chance of developing active TB because a weakened immune system struggles to suppress the bacteria. Lower bacterial loads in such patients may occasionally affect test sensitivity.
- People with diabetes mellitus face a two to four times higher risk of active TB compared to those without diabetes. Up to 30% of TB patients may also have diabetes, so results in this group require careful clinical assessment.
- Patients who have previously been treated for TB may show altered results, particularly in follow-up cultures used to confirm treatment response.
How to Maintain Health and Prevent Infection
The following general wellness measures support respiratory and immune health:
- Ensure good ventilation in your home and workplace to reduce the risk of airborne infections
- Eat a balanced diet with adequate protein and micronutrients to support immune function
- Seek medical attention promptly if you develop a persistent cough, night sweats, or unexplained weight loss
Lupin Diagnostics GeneXpert MTB Culture (MTB Culture) Test Price and Home Collection
The GeneXpert + MTB culture panel is available at Lupin Diagnostics starting at approximately ₹2,200. While convenient home sample collection is available for standard sputum samples across major cities, please note that patients requiring invasive extrapulmonary fluid collections (like CSF or pleural fluid draws) must visit the diagnostic centre to have the sample securely taken by medical staff.
The table below shows indicative prices by city.
| City | Approximate Price (₹) |
|---|---|
| Bangalore | ₹2,200 |
| Mumbai | ₹2,800 |
| Pune | ₹2,800 |
| Hyderabad | ₹2,200 |
| Chennai | ₹2,200 |
| Kolkata | ₹2,800 |
| Indore | ₹2,800 |
| Bhopal | ₹2,800 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website
- Choose your city and preferred time slot
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre
- Receive your report via email or WhatsApp within the stipulated turnaround time
Home Collection
Home collection for the GeneXpert MTB combo test is available across major Indian cities, with samples collected by trained professionals and processed in NABL-accredited laboratories. Digital reports are delivered to your registered email or WhatsApp, so there is no need to visit the lab to collect them.
Frequently Asked Questions
The GeneXpert + MTB culture panel uses two different methods. GeneXpert is a molecular test that detects TB bacterial DNA and checks for rifampicin resistance within about two hours. The MTB culture actually grows the bacteria in the laboratory and can take two to six weeks, but it provides a complete picture of drug resistance across multiple medicines.
GeneXpert delivers fast results that allow doctors to start treatment quickly, while the culture provides a thorough check of drug sensitivity beyond just rifampicin. Used together as a TB comprehensive panel, the two tests offer both speed and depth of information.
Liquid culture systems typically report positive results within 10 to 21 days. If no bacteria grow, the culture is held for up to six weeks before a negative result is confirmed. Solid media culture can take six to eight weeks in total.
No. People with latent TB do not have active bacteria in their sputum, so both the GeneXpert and culture results will be negative. Latent TB is identified through blood-based tests such as IGRA or skin tests, not sputum-based panels.
Sputum is the preferred sample for suspected lung TB. For TB outside the lungs, other samples such as pleural fluid, cerebrospinal fluid (CSF), gastric aspirate, lymph node material, urine, or pus may be used. Your doctor will decide which sample is appropriate based on your symptoms.
Yes. GeneXpert is particularly useful in children because TB in this age group often involves very low bacterial counts, making it harder to detect by conventional methods. Molecular testing provides quicker and more reliable detection in paediatric cases compared to standard microscopy.
No. The GeneXpert test detects bacterial DNA, including DNA from bacteria that are no longer alive. This means it can show a positive result even after successful treatment. Only MTB culture results are appropriate for monitoring treatment response.
GeneXpert MTB Culture (MTB Culture) Test
