Question

Describe the various steps in Gram's staining procedure?

Answer 1

Gram staining is a process of staining bacterial cells. The bacterial cells that retain the stain at the end of the process are termed Gram +ve, while those which do not retain are Gram -ve.

The process uses three stains, crystal violet, Gram's iodine and safranin. Waiting period for stains is approximately 60secs

The specimen to be stained is fixed on to the slide (Air flow dried / heat fixed)

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Stained with crystal violet

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water is allowed to flow slow over the slide to remove excess stain

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Gram's iodine a mordant is added

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water is allowed to flow slow over the slide to remove excess stain

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The specimen is counter stained with Safranin

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water is allowed to flow slow over the slide to remove excess stain

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The specimen is then observed under a compound light microscope

If crystal violet stain is retained, the specimen is Gram +ve and it appears violet

If it is not, then, the specimen is Gram -ve and it appears pink