AFB C/S (Joint Fluid for Mycobacterium Tuberculosis)

Specimen Required

JOINT FLUID

Fasting Required

Purpose of the Test

The AFB C/S (Acid-Fast Bacilli Culture and Sensitivity) test for Joint Fluid samples is used to detect the presence of Mycobacterium tuberculosis (MTB) in a patient’s joint fluid. The test helps diagnose tuberculosis (TB) infection in patients who have symptoms such as joint pain, stiffness, swelling, and limited range of motion.

When this test is required

The AFB C/S test requires a sample of the patient’s joint fluid, which is collected using a needle that is inserted into the joint. The sample is then sent to a laboratory for analysis. In the laboratory, the joint fluid is processed and cultured in a special medium that promotes the growth of MTB. If MTB is present in the joint fluid sample, it will grow within the culture, and the laboratory can then identify the organism and perform a sensitivity test to determine which antibiotics will effectively treat the infection.

What the Test Detects

Preparation for the Test

No special preparation is required for the AFB C/S test for Joint Fluid. However, the patient may be instructed to avoid certain medications, such as antibiotics, before the test, as these can interfere with the accuracy of the test results.

Sample Requirements

The test requires a sample of the patient’s joint fluid, which is collected using a needle that is inserted into the joint. The sample is then sent to a laboratory for analysis. In the laboratory, the joint fluid is processed and cultured in a special medium that promotes the growth of MTB. If MTB is present in the joint fluid sample, it will grow within the culture, and the laboratory can then identify the organism and perform a sensitivity test to determine which antibiotics will effectively treat the infection.

Additional Notes

It is important to note that a negative result on the AFB C/S test does not necessarily mean that the patient does not have TB infection. It is possible for the test to produce a false negative result, particularly if the MTB bacteria are present in low numbers in the joint fluid or if the patient has received antibiotic treatment prior to the test. Therefore, additional testing may be required to confirm a TB diagnosis.

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