[Histonet] Gram Stain

[John Kiernan]

I don't know a method to obtain selective red coloration of Gram-negative organisms, with yellow for both Gram-positives and "background", and I cannot find one by looking in various books. It may not be possible because Gram-positivity relies on selective retention of an immobilized dye. Gram-negative bacteria stain only because the red dye is excluded by the organisms already filled with an insolubilized blue-purple dye in the Gram-positive cells.
The Brown-Hopps modification of Gram staining for paraffin sections clearly separates blue from red bacteria and gives a quite different yellowy-brown counterstain to the "tissue background".  This is explained and well  illustrated in Freida Carson's textbook.  (I have only the 2nd edition, 1997; there is now a 5th, 2020, ISBN 9780891896760.)
John Kiernan  (London, Ontario)
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________________________________
From: Rhonda McCormick via Histonet <histonet at lists.utsouthwestern.edu>
Sent: August 30, 2023 2:42 PM
To: Histonet <histonet at lists.utsouthwestern.edu>
Subject: [Histonet] Gram Stain

Howdy,Does anyone have a recommendation for a Gram stain (or modification of a gram stain) that stains the background yellow with red gram-negative bacteria  (no blue - gram positive staining).Thank you!
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