Gram’s Stain: From 3 Different Sources
An iodine-based stain that is used to differentiate between types of bacterium.
Stain developed in 1884 by Hans Christian Gram, whereby Gram positive bacteria stain purple while Gram negative bacteria stain red.
a method of staining bacterial cells, used as a primary means of identification. A film of bacteria spread onto a glass slide is dried and heat-fixed, stained with a violet dye, treated with decolourizer (e.g. alcohol), and then counterstained with red dye. Gram-negative bacteria lose the initial stain but take up the counterstain, so that they appear red microscopically. Gram-positive bacteria retain the initial stain, appearing violet microscopically. These staining differences are based on variations in the structure of the cell wall in the two groups. [H. C. J. Gram (1853–1938), Danish physician]
See NAEVUS.... port wine stain
Gram’s Method is a staining procedure that separates bacteria into those that stain (positive) and those that don’t (negative). Gram-positive bugs cause such lovely things as scarlet fever, tetanus, and anthrax, while some of the gram negs can give you cholera, plague, and the clap. This is significant to the microbiologist and the pathologist; otherwise I wouldn’t worry. Still, knowing the specifics (toss in anaerobes and aerobes as well), you can impress real medical professionals with your knowledge of the secret, arcane language of medicine.... gram-positive/negative
The effect of the two ends of a bacillus staining while the centre of the rod remains unstained (eg in Yersinia pestis, the cause of Bubonic Plague) when stained with Giemsa stain.... bipolar staining
Bacteria can be stained with an iodine-based chemical dye called Gram’s stain (after the scientist who discovered the technique). Different bacteria react di?erently to exposure to the stain. Broadly, the bacterial specimens are stained ?rst with gentian violet, then with Gram’s stain, and ?nally counterstained with a red dye after a decolorising process. Bacteria that retain the gentian stain are called gram-positive; those that lose it but absorb the red stain are called gram-negative. Some species of staphylococcus, streptococcus and clostridium are gram-positive, whereas salmonella and Vibrio cholerae are gram-negative.... gram’s stain
One of the Romanowski stains used to stain blood films and blood parasites such as those causing relapsing fever, malaria trypanosomiasis and filariasis.... wright’s stain
The process of dyeing specimens of cells, tissues, or microorganisms in order for them to be clearly visible or easily identifiable under a microscope.... staining
a mixture of *methylene blue and *eosin, used for distinguishing different types of white blood cell and for detecting parasitic microorganisms in blood smears. It is one of the *Romanowsky stains. [G. Giemsa (1867–1948), German chemist]... giemsa’s stain
a histological stain consisting of water-soluble aniline blue or methyl blue, orange G, and oxalic acid. Before the stain is applied the tissue is mordanted, then treated with acid fuchsin and phosphomolybdic acid. Nuclei stain red, muscle red to orange, nervous tissue lilac, collagen dark blue, and mucus and connective tissue become blue. [F. B. Mallory]... mallory’s triple stain
a group of stains used for microscopical examination of blood cells, consisting of variable mixtures of thiazine dyes, such as azure B, with eosin. Romanowsky stains give characteristic staining patterns, on the basis of which blood cells are classified. The group includes the stains of Leishmann, Wright, May-Grünwald, Giemsa, etc. [D. L. Romanowsky (1861–1921), Russian physician]... romanowsky stains
1. n. a dye used to colour tissues and other specimens for microscopical examination. In an acid stain the colour is carried by an acid radical and the stain is taken up by parts of the specimen having a basic (alkaline) reaction. In a basic stain the colour, carried by a basic radical, is attracted to parts of the specimen having an acidic reaction. Neutral stains have neither acidic nor basic affinities. A contrast stain is used to give colour to parts of a tissue not affected by a previously applied stain. A differential stain allows different elements in a specimen to be distinguished by staining them in different colours. 2. vb. to treat a specimen for microscopical study with a stain.... stain
a group of azo compounds used for staining fats. The group includes Sudan I, Sudan II, Sudan III, Sudan IV, and Sudan black.... sudan stains
the application of a *stain to living tissue, particularly blood cells, removed from the body.... supravital staining
(intravital staining) the process of staining a living tissue by injecting a stain into the organism. Compare supravital staining.... vital staining
an acid-fast *carbol fuchsin stain used specifically for identifying the tubercle bacillus. [F. Ziehl (1857–1926), German bacteriologist; F. K. A. Neelsen (1854–94), German pathologist]... ziehl–neelsen stain
Health Encyclopedia