Afb Zn Stain Microscopy Bronchoalveolar Lavage

This test is used to detect and identify infections caused by acid-fast bacilli. This test helps in diagnosing tuberculosis which is caused by Mycobacterium tuberculosis or any other infection caused by Mycobacterium like leprosy. For this test usually, bronchoalveolar lavage is collected by your healthcare provider.

What is ZN (Ziehl-Neelsen) Stain?

ZN Staining is a classic procedure for staining acid-fast bacilli. In the ZN hot technique, the stain (phenol-carbol fuchsin) is heated so that the dye can penetrate the mycobacterial cell wall. This dye binds to the mycolic acid in the mycobacterial cell wall. After staining the mycobacterial cells an acid decolorizing solution is added which removes the red dye from the background cells, tissue fibers, any other organisms in the smear except mycobacteria which retain the dye. Hence they are called acid-fast bacilli.

What are mycobacterial infections?

Mycobacterium is a type of germ. There are different kinds of Mycobacterium like Mycobacterium tuberculosis, Mycobacterium ulcerans, Mycobacterium leprae. Mycobacterium tuberculosis causes tubercular infection. It mostly affects the lungs. It can also spread to other parts of the body like the brain and spine. The symptoms of tuberculosis of lungs are a severe cough that lasts for more than 3 weeks, sometimes cough with blood, chest pain, feeling tired most of the day, sweating at night, fever with chills, loss of appetite, weight loss, etc. The symptoms of tuberculosis other than lungs, like leprosy, are skin discoloration, thickened skin, skin lesions, skin plaques, skin nodules, nasal congestion, nose bleeds, etc. Mycobacterium infection can spread through the air when the infected person has a cold or flu. When the person sneezes, coughs, talks, laughs, the tiny droplets that contain germs are released. If these are inhaled by the healthy individuals the infection will get transmitted to them.

Why this test is performed?

This test may be recommended to you if you experience certain symptoms like a severe cough that lasts for more than 3 weeks, sometimes cough with blood, chest pain, feeling tired most of the day, sweating at night, fever with chills, loss of appetite, weight loss, etc. This test is also recommended if you have a positive TB blood test or a positive TB skin test. This test is recommended in HIV positive patients because of their weakened immune system. This test is also recommended to people who are in hospitals, nursing home, or correctional facilities. If you experience symptoms of TB other than lungs, then also this test is recommended. These symptoms vary according to the site of infection.

The reference range may vary depending on gender, age, health history, health condition, etc.

If your test results are negative, then it may indicate that there are no signs of growth of Mycobacterium.

If your test results are positive, then it may indicate that you may have tuberculosis.

If abnormal test results were seen, consult your doctor immediately with your lab test reports.