Question

Arrange the following steps in correct order as per Gram’s staining technique
1) Treatment with 0.5% Iodine solution
2) Counter staining with safranin
3) Treatment with absolute ethanol
4) Staining heat fixed smear with crystal violet

• A. 4, 1, 3, 2
• B. 3, 2, 1, 4
• C. 3, 1, 2, 4
• D. 4, 2, 3, 1

Answer 1

The correct option is A 4, 1, 3, 2

Steps in Gram's staining

1. Applying a primary stain (crystal violet) to a heat-fixed smear of a bacterial culture.
2. The addition of iodine, which binds to crystal violet and traps it in the cell.
3. Rapid decolorization with ethanol
4. Counterstaining with safranin.