|bacteriol Gram-negative See also Gram-positive a staining technique used to classify bacteria, based on their ability to retain or lose a violet colour, produced by crystal violet and iodine, after treatment with a decolorizing agent|
|[C19: named after Hans Christian Joachim Gram (1853--1938), Danish physician]|
Gram's method (grāmz)
A staining technique used to classify bacteria in which a bacterial specimen is first stained with crystal violet, then treated with an iodine solution, decolorized with alcohol, and counterstained with safranine. Gram-positive bacteria retain the violet stain; gram-negative bacteria do not. Also called Gram's stain.