What are the procedures of acid-fast stain?
Posted March 16, 2023
Answer
Acid-fast stain is a complex procedure that allows scientists to visualize acid-fast bacteria. Here’s an overview of the acid-fast stain procedure:
- The specimen smear must be prepared and fixed before it can be stained.
- A small strip of filter or blotting paper is placed over the specimen.
- The slide is placed on a mesh surface over a beaker of steaming water. Care must be taken not to let the water evaporate completely.
- Carbolfuchsin, which is the primary stain, is poured over the filter or blotting paper and the slide is left over the steaming water bath for about 3 to 5 minutes. If the paper starts to dry, more stain can be applied to keep it damp throughout.
- After 3 – 5 minutes, the filter paper is removed and the slide is rinsed gently with water until the solution runs clear.
- Acid-alcohol decolorizer is then run over the slide for about 15 to 30 seconds, then rinsed with water and left to dry naturally.
- The smear is covered with the secondary or counterstain, methylene blue, for about 1 – 1.5 minutes.
- The slide is rinsed gently with water and blotted dry on both sides with bibulous paper.
- The dry slide is placed on the microscope staged and viewed with an oil immersion lens.
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