What stain should you use for tuberculosis?
Acid-Fast Bacteria—Ziehl– Neelsen Stain This stain is used to identify Mycobacterium tuberculosis, the causative agent of tuberculosis.
Which staining method is used for detection of TB bacteria in sputum?
Sputum smear microscopy using the ubiquitous Ziehl-Neelsen (ZN) stain, the primary diagnostic strategy for active tuberculosis (TB) worldwide that is recommended by the World Health Organization (WHO),1 is constrained by its reliance on human skill and time-intensive nature.
Why is acid fast stain used for tuberculosis?
Sputum, or phlegm, is often used to test for Mycobacterium tuberculosis, to find out if a patient has TB. This bacterium is completely acid-fast, which means the entire cell holds onto the dye. A positive test result from the acid-fast stain confirms the patient has TB.
What color does tuberculosis stain?
Acid alcohol has the ability to completely decolorize all non-acid-fast organisms, thus only leaving behind red-colored acid-fast organisms, like M. tuberculosis. The slides are then stained a second time with methylene blue that serves as a counterstain.
How do you stain sputum for AFB?
Sputum stain test Your sputum specimen will be spread on a microscope slide. A staining dye is added to the cells of the specimen and then washed in an acid solution. The cells are then examined under a microscope. If the cells retain the stain, this means mycobacterium are present.
What does AFB stain for?
AFB smear—a microscopic examination of a person’s sputum or other specimen that is stained to detect acid-fast bacteria. It is a rapid test used to provide presumptive results within one to two days.
What is AFB in sputum test?
AFB smear—a microscopic examination of a person’s sputum or other specimen that is stained to detect acid-fast bacteria. It is a rapid test used to provide presumptive results within one to two days. It is valuable in helping to make decisions about treatment while waiting for culture results.
What is AFB sputum test?
What is AFB stain used for?
How do you perform a Zn stain?
Ziehl Neelsen Acid-fast stain
- Step 2: Smear Preparation (Review)
- Cover the smear with carbolfuchsin dye.
- Dry heat for 2 minutes.
- Cool and rinse with water.
- Wash the top and bottom of slide with water and clean the slide bottom well.
- Counterstain with Methylene Blue for 30 seconds to 1 minute.
What is the principle of AFB staining?
The mycobacterial cell wall contains mycolic acids, which are fatty acids that contribute to the characteristic of “acid-fastness.” The principle of the AFB smear is based on the fact that mycolic acid in the cell wall of AFB render them resistant to decolorization with acid alcohol.
Why is TB bacilli called AFB?
Mycobacteria are called acid-fast bacilli because they are rod-shaped bacteria (bacilli) that can be seen under the microscope following a staining procedure in which the bacteria retain the color of the stain after an acid wash (acid-fast).
How is the Kinyoun method used for AFB staining?
In the ‘ cold ’ technique known as Kinyoun Method, stain are not heated but the penetration is achieved by increasing concentration of basic fuchsin and phenol and incorporating a ‘wetting agent’ chemical. The stain binds to the mycolic acid in the mycobacterial cell wall. After staining, an acid decolorizing solution is applied.
How is sputum smear used to diagnose tuberculosis?
The technique is simple and inexpensive, and detects those cases of tuberculosis, which are infectious. Sputum microscopy is also useful to assess the response to treatment, and to establish cure or failure at the end of treatment. BACKGROUND INFORMATION
How are mycobacteria stained in the Hot ZN technique?
Mycobacteria, which do not stain well by Gram stain, are stained with carbol fuchsin combined with phenol. In the ‘ hot’ ZN technique, the phenol-carbol fuchsin stain is heated to enable the dye to penetrate the waxy mycobacterial cell wall.
How to make a fluorescence stain for sputum?
Auramine-Phenol solution: Warm 100 ml stock of three percent phenol to 40°C. To this add gradually 0.3 gm of Auramine with vigorous shaking for 10 minutes. Filter and store in a dark brown bottle. The stain should not be kept for more than 3 weeks. A standard good quality powder of “Auramine O” should be used (see specifications).