WHAT IS AFB SMEAR/ ZN STAIN TEST?
BIOPSY: A biopsy is the removal of a small amount of tissue. In this procedure doctor diagnose many different types of fungal infections refer to tissue which has been removed from a living body for examination, to discover the presence, cause, or extent of a disease.
WHAT DOES THE TEST MEASURES?
AFB smear helps in the diagnosis of active Mycobacterium tuberculosis infections as well as infections due to nontuberculous mycobacteria (bacteria found in soils and water). AFB smear is less sensitive than an AFB culture.
The AFB smear test is reported in 24 hours.
FREQUENTLY ASKED QUESTIONS:
Q1. How is the test performed?
- For the Nasal swab AFB smear test, secretions are collected using a swab from the back of the nose and upper throat. Sometimes, a suction device is used to remove the secretions.
- For pleural fluid, sputum is the most commonly collected sample. Sputum is thick mucus that is coughed up from the lungs. If a person is unable to produce sputum, a healthcare practitioner may collect respiratory samples using a procedure known as bronchoscopy. The practitioner will insert a tube into the bronchi and smaller
- Bronchioles and aspirate fluid samples for testing.
- For blood AFB smear, a blood sample is collected.
Q2. Is there any risk associated with this test?
No risk is associated with the test.
Q3. What is the difference between tuberculosis and pneumonia?
Tuberculosis is a contagious bacterial disease while pneumonia is not contagious.
Q4. What are the signs and symptoms of active tuberculosis?
Signs and symptoms of active tuberculosis include
- Coughing that lasts 3 or more weeks
- Cough with blood
- Chest pain
- Pain with breathing or coughing
Q5. How is Mycobacterium spread?
Mycobacterium tuberculosis is carried in airborne particles. TB is spread from person to the person through the air
INTERPRETATION OF THE RESULTS:
- A negative AFB smear may mean that no infection is present, that symptoms are caused by something other than mycobacteria, or that the mycobacteria were not present in sufficient numbers to be seen under the microscope. Usually, three samples are collected to increase the probability that the organisms will be detected.
- If AFB smears are negative and there is still a strong suspicion of mycobacterial infection, then additional samples may be collected and tested on different days.
- A smear negative sample may still grow mycobacteria since the culture media allows low numbers of bacteria that cannot be seen in a microscopic examination to multiply and be detected.
- Positive AFB smears indicate a probable mycobacterial infection. However, a culture must be performed to confirm a diagnosis and identify the species of mycobacteria present.
For people with signs and symptoms of an active TB infection, AFB smear results are considered together with results from NAAT for TB, as recommended by the Centers for Disease Control and Prevention. Though definitive diagnosis requires results from a culture, results from the smear and NAAT may help decide what to do. For example, if there is a presumptive diagnosis of TB based on rapid test results, most health practitioners would treat.