Question
Staining procedure, discovered by Ehrlich, as shown in Photograph
A. Methylene blue stain
B. Silver impregnation stain
C. Acid fast stain
D. Gram stain
Show Answer
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Correct Answer » C Explanation |
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Ans:C.Acid fast stain
In the above image of Acid fast Stain, Bright red to intensive purple (B), straight or slightly
curved rods, occurring singly or in small groups-they are acid fast bacilli,
Non-acid fast: Blue color (A).
Acid Fast Stain
- It is the differential staining techniques which was first developed by Ziehl and later on modified by Neelsen. So this method is also called Ziehl-Neelsen staining techniques.
- Carbol-fuchsin and heat are used,then decolorized with an acid alcohol, and counter stained with methylene blue.
- The main aim of this staining is to differentiate bacteria into acid fast group and non-acid fast groups.
- This method is used for those microorganisms which are not staining by simple or Gram staining method, particularly the member of genus Mycobacterium, are resistant and can only be visualized by acid-fast staining.
Acid-fast organisms:
- Mycobacterium tuberculosis, Mycobacterium smegmatis.
- Non-Mycobacterial bacteria: Nocardia
- Coccidian Parasites: Cryptosporidium
- They 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
- The acid-fast genera have lipoidal mycolic acid in their cell walls.
- It is assumed that mycolic acid prevents acid-alcohol from decolorizing protoplasm.