Acid Fast Bacilli (AFB) Smear, Genexpert Ultra MTB/RIF, TB Culture, MGIT

What is the TB culture MGIT test?

Millions of individuals are affected by tuberculosis each year, which is still a serious health concern in the world. Controlling the condition requires a precise and quick diagnosis. Fever, coughing, and weight loss are symptoms of the chronic respiratory illness tuberculosis. Mycobacterium tuberculosis frequently causes it (M.tb). Staining, culture, and nucleic acid detection are only a few of the several diagnostic methods available for the diagnosis of TB. Among the methods for finding nucleic acids include polymerase chain reaction (PCR), cartridge-based nucleic acid amplification technique (CBNAAT), line probe assay (LPA), and next-generation sequencing (NGS).

A culture method used to find M.tb is called a Mycobacterium growth indicator tube (MGIT). A fluorescent dye is used in the liquid culture test, which yields results in 7 to 10 days. To diagnose the condition and do further susceptibility testing, this test is used to isolate M.tb in pure culture. It is regarded as the benchmark for M. tb diagnosis.

The test is also called:

• TB Culture and Sensitivity
• AFB Smear and Culture
• Mycobacteria Smear and Culture

What is the Purpose of the TB culture MGIT test?

Mycobacterium species or the Mycobacterium tuberculosis complex may be quickly and precisely diagnosed using this method. It combines growth supplements that promote the growth of mycobacteria and extra antibiotic supplements that prevent the formation of additional pathogenic bacteria, ensuring the purity of the mycobacteria. WHO and RNTCP both endorse this approach. Compared to the traditional L. J. solid culture method, it has a 15-20% higher culture-positive rate.

What does TB culture MGIT test diagnose?

So, medical professionals can assess if a TB bacteria thrives in the culture, indicating whether or not the TB bacterium is responsive to the TB medications that are being tested, much more quickly. This implies that patients can obtain the right medications more quickly and receive effective, timely treatment. The increased risk of contamination in liquid culture methods is a significant drawback. This implies that other germs may enter the system more readily, leading to inflammation.

The MGIT test finds M.tb or other mycobacteria that are not tuberculous in samples. Furthermore, leprosy and other respiratory illnesses are detected with it. The test is used to identify active TB brought on by M. tb.

Why do you need a TB culture MGIT test?

If you show signs of active TB, a TB Culture MGIT test may be necessary. They comprise:

• coughing for at least three weeks
• having a bloody or sputum cough
• an ache in the chest
• Fever
• Fatigue
• sleepless nights
• Loss of weight without cause

Other than the lungs, the body might exhibit signs of active TB. The symptoms change depending on which bodily area is impacted. Thus, if you have: you could require testing.

• Pain in the back
• Urine containing blood
• Headache
• Joint pain
• Fever
• Fatigue
• night sweats
• Mysterious weight reduction

Depending on your risk factors, you could additionally require tests. The following may increase your chance of developing TB:

• Had a strong relationship with a person who had TB and had been diagnosed
• Possess HIV or another immune-depleting illness
• Living in a location where tuberculosis infections are prevalent or working there. Inmates' facilities, nursing homes, and destitute shelters are among the examples.
• chest discomfort

In addition to the lungs, the body might exhibit signs of active TB. Each damaged body part has a unique set of symptoms.

Preparation and procedure required for TB culture MGIT test

Specimens must be gathered in sterile, clean containers with tight-fitting lids or caps. Each new case should have at least two-morning samples that were taken on different days. The specimens for patients who have respiratory symptoms should be expectorated sputum, not saliva, and should have a volume of between 2 and 10 ml each.

• The culture will require a sample of your sputum.
• You will be instructed to spit into a sterile container after coughing loudly. This will need to be done over the course of two or three days.
• By doing this, you can ensure that your sample contains enough bacteria for testing.
• If you are having difficulties producing enough sputum, your doctor may urge you to inhale a sterile saline (salt) mist, which can encourage deeper coughing.
• If you still struggle to produce enough sputum, your doctor could carry out a procedure called a bronchoscopy.
• You will be given medication to numb the discomfort.
• Next, your mouth or nose will be used to insert a tiny, lit tube into your airways. Suction or a tiny brush might be used to gather the sample.

Understanding TB culture MGIT test results

Results from a typical sputum culture can be obtained in 1 to 8 weeks. Within 24 hours, a quick sputum test can determine if someone has TB. When a person is suspected of having TB but sputum culture findings need to be confirmed, a test may be performed.

• Original specimen fluorescent acid-fast stain: 24-72 hours after laboratory receipt.
• When feasible, but no later than 14–21 days after receiving the material, identify M. tuberculosis from culture.
• Results of M. tuberculosis susceptibility tests must be obtained as soon as feasible, but no later than 15–30 days after receiving the specimen.

M.tb was discovered, indicating that M.tb was cultivated from the material. According to the advice of the treating physician, this growth can be employed for assessing the susceptibility of different antibiotics.

M.tb Not detected - This indicates that M.tb could not be grown from the sample and that it is unlikely that the patient has TB. Your doctor may order further tests for detection, such as PCR because this test's sensitivity is not 100%. 

You have an active TB infection if your culture test results are positive. To choose your course of therapy, your doctor may also suggest susceptibility testing. You do not have an active TB infection if the culture test yields a negative result. The sample might not have had enough germs to enable accurate identification, though. Hence, if you experience symptoms, your doctor could advise you to repeat the test or run another test to confirm the results.