PUS SWAB for AFB Smear/ZN Stain

Specimen Required

SWAB

Fasting Required

Purpose of the Test

This test is primarily performed to diagnose tuberculosis and other infections caused by Mycobacterium species that can infect soft tissues, wounds, and other parts of the body. The test helps identify the presence of acid-fast bacilli, which are characteristic of mycobacterial infections.

When this test is required

The test is requested when a mycobacterial infection is suspected based on clinical symptoms and history, such as tuberculosis or non-tuberculous mycobacterial infections.

What the Test Detects

The test is used to detect the presence of acid-fast bacilli in the sample obtained from the infected site. Acid-fast bacilli have a unique cell wall structure that makes them resistant to the decolorizing agent used in the ZN staining technique. The acid-fast bacilli appear red when viewed under a microscope after staining, whereas other bacteria and cells appear blue.

Preparation for the Test

No special preparation is needed for this test.

Sample Requirements

A pus swab or discharge from the infected site is required for this test.

Additional Notes

The test is a quick and inexpensive way to screen for mycobacterial infections, but it has limitations. False positives and false negatives can occur, and the test cannot identify the specific type of mycobacterium causing the infection. Therefore, it is usually followed up with other diagnostic tests, such as culture and sensitivity testing, for confirmation and identification of the specific organism.

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