Gram Stain Modification

 The Original Gram Stain was developed by Christian Gram in 1884. It was then subjected to several modifications which will be discussed in this blog.

Gram staining is a differential staining technique routinely done in microbiology laboratories. The prime motive of the method is to differentiate bacteria's into 2 groups:

• Gram Positive bacteria
• Gram Negative bacteria

This initial differentiation provides easy diagnostic approach to identify the bacteria that causes the infection. 

It's been several decades since this method was originally devised yet still it's used as the first and foremost diagnostic procedure in all the microbiological laboratories.

Here I listed out the several modifications of gram staining:

 

ORIGINAL METHOD :(Christian Gram)

Primary stain - Gentian violet

Mordant - Lugol's Iodine

Decolourizer - Absolute alcohol

Counter stain - Bismarck brown

KOPELOFF'S & BEERMAN'S MODIFICATION:

Primary stain - Methyl violet for 5 mins

Mordant - Iodine for 2 mins

Decolourizer - Acetone for 2-3 secs

Counter stain - Basic Fuchsin for 30 secs

JENSEN'S MODIFICATION:

Primary stain - Methyl violet for 30 secs

Mordant - Lugol's Iodine for 30 secs

Decolourizer - Absolute alcohol for 30 secs

Counter stain - Neutral red for 2 mins

WEIGERT'S MODIFICATION(for tissue sections)

Primary stain - Methyl violet for 30 secs

Mordant - Lugol's Iodine for 30 secs

Decolourizer - Aniline xylene 

Counter stain - Neutral red for 2 mins

PRESTON & MORRELL'S MODIFICATION:

Primary stain - Ammonium oxalate crystal violet for 30 secs

Mordant - Lugol's Iodine for 30 secs

Decolourizer - Iodine acetone for 30 secs

Counter stain - Dilute carbol fuchsin for 30 secs

HUCKER'S MODIFICATION:

Primary stain - Ammonium oxalate crystal violet for 60 secs

Mordant - Gram's Iodine for 60 secs

Decolourizer -  Acetone alcohol for 10 secs

Counter stain - Saffranin for 30 secs

QUICK METHOD:

Primary stain - Methyl violet (or) crystal violet for 5 secs

Mordant -  Iodine for 5 secs

Decolourizer -  Acetone for 2 secs

Counter stain - Basic fuchsin for 5 secs

References:

1. Koneman's color atlas & textbook of diagnostic Microbiology - 7th edn.

2. Mackie & MacCartney practical medical microbiology - 14th edn.

3. Youtube.com