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Flashcards in Lab 6 Deck (10):
1

1. What are the 8 steps and reagents used in the acid-fast stain?

1. place small paper towel over slide
2. saturate paper towel with carbolfuchsin, let sit 1 minute
3. apply gentle heat, keep moist for 5 minutes
4. remove paper and let for 1 minute
5. rinse slide with water until clear
6. decolorize with acid/alcohol until colorless
7. rinse with water and counterstain with Methylene Blue for 1 minute
8. rinse with water and blot dry

2

What is the function Carbolfuchsin?

turns cell reddish purple color, this is lipid soluble and penetrates the waxy cell

3

What is the function of steam heat?

enhances the entry of carbofuchsin into cells. Heat melts the wax and allows cells to penetrate.

4

What is the function of the acetone/alcohol?

removes the stain from acid fast negative cells. Acid fast cells resist decolorization.

5

What is the function of the Methylene Blue?

counterstains acid fast negative cells and turns them blue.

6

What color is acid fast positive?

pink

7

What color is acid fast negative?

blue

8

2. What two genera did we discuss that are acid-fast bacteria?

Mycobacteria and Nocardia

9

3. What component of their cell wall is responsible for their acid-fast property?

The waxy substance (mycolic acid) is compatible with the primary stain and resistant to decoloization by the acid/alcohol solution.

10

4. What important diseases are associated with acid-fast bacteria?

TB, Leprosy, HIV/AIDS