What are the steps in acid fast staining?
Examples of Acid-Fast Stain. Mycobacterium tuberculosis visualization using the Ziehl–Neelsen stain. Acid-fast: Mycobacterium tuberculosis, Mycobacterium smegmatis.
What is acid fast staining?
The acid-fast stain is a laboratory test that determines if a sample of tissue, blood, or other body substance is infected with the bacteria that causes tuberculosis (TB) and other illnesses.
What are the five acid fast staining methods?
Acid-Fast Staining Instructions
- Air dry and heat fix a thin film of microorganisms.
- Flood the slide with Carbolfuchsin.
- Flood slide with Acid Alcohol for 30 seconds.
- Counterstain by flooding the slide with Methylene Blue for 30 seconds.
- Dry the slide by putting it between the pages of a book of Bibulous paper.
What does an acid fast stain look like?
Acid fast bacteria have a high content of mycolic acids in their cell walls. Acid fast bacteria will be red, while nonacid fast bacteria will stain blue/green with the counterstain with the Kinyoun stain.
Which method of staining is used to demonstrate acid-fast?
The Ziehl Neelsen (ZN) method of staining acid fast bacilli has been in vogue for more than hundred years. In the ZN method [1], the basic fuchsin phenol dye is used hot there by melting the unsaponifiable waxy substance on the surface of the cell wall.
Why mycobacteria are called acid-fast?
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).
Why does acid-fast staining work?
Acid-fast organisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex lipids. The primary stain used in acid-fast staining, carbolfuchsin, is lipid-soluble and contains phenol, which helps the stain penetrate the cell wall.
What is the difference between Gram stain and acid fast stain?
The main difference between Gram stain and acid fast stain is that Gram stain helps to distinguish bacteria with different types of cell walls whereas acid-fast stain helps to distinguish Gram-positive bacteria with waxy mycolic acids in their cell walls.
Why it is called acid fast staining?
Mycobacterium and many Nocardia species are called acid-fast because during an acid-fast staining procedure they retain the primary dye carbol fuchsin despite decolorization with the powerful solvent acid-alcohol. Nearly all other genera of bacteria are nonacid-fast. The acid-fast stain is a differential stain.
Why is methylene blue used in acid fast staining?
After the auramine dye has fully stained the smear, a drop of acid alcohol is applied for one to two minutes to decolorize the smear. Methylene blue or potassium permanganate is used as a counterstain to provide background color.