1. THE GRAM STAIN

2. It is called a The gram stain
is the most widely used staining procedure in bacteriology
It is called a
differential stain
since it differentiates between gram-positive and gram-negative bacteria.
Bacteria that stain
purple
with the gram staining procedure are termed
gram-positive.and those that stain Pink
are said to be
gram-negative

3. The bacteria are stained with the basic dye crystal violet
gram staining procedure
The bacteria are stained with the basic dye crystal violet
Both gram-positive and gram-negative bacteria become directly stained and appear purple after this step.

4. The bacteria are treated with
gram's iodine solution
Both gram-positive and gram-negative bacteria remain purple after this step.

5. then added ( Gram's decolorizer ) )
(ethyl alcohol). This is the differential step. Gram-positive bacteria retain the crystal violet-iodine complex while gram-negative are decolorized

6. Finally, the counterstain
(safranin )
Since the gram-positive bacteria are already stained purple, they are not affected by the counterstain. Gram- negative bacteria are now colorless, become directly stained by the safranin
gram-positive appear purple
gram-negative appear pink

7. Crystal
Gram ’ s
(Primary stain)
Gram’s
violet
iodine
Safranin
Alcohol

8. 1-Preparing the Slide for Staining then
Heat-fix a smear
You do heat the slide to
ensure that it does not wash off during the staining process

9. 2-Stain with crystal violet for one minute
with water Gently wash

10. 3-Stain with gram's iodine solution For one minute then
Wash with water

11. 4-Decolorize by adding gram's decolorizer(alchol
Wash immediately with water

12. Stain withsafranin for two minutes
wash with water

13. Dry and observe

14. Answer: Gram-positive streptococcus

15. Answer: Gram-negative bacilli