Gram's stain


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Gram's stain

Etymology: Hans C.J. Gram
the method of staining microorganisms using a violet stain, followed by an iodine solution; decolorizing with an alcohol or acetone solution; and counterstaining with safranin. The retention of either the violet color of the stain or the pink color of the counterstain serves as a primary means of identifying and classifying bacteria. Also called Gram's method. See also gram-negative, gram-positive.

Gram's stain

a stain taken up by the Gram-positive bacteria that differentiates these from bacteria which fail to take up the stain (Gram-negative types). The initial stain is crystal violet/iodine complex, and Gram-negative bacteria are decolorized with alcohol whilst Gram-positive bacteria retain a blue/purple colour.

Gram's stain

A stain used in microbiology to classify bacteria and help identify the species to which they belong. This identification aids in determining treatment.

Gram's stain

method of differential bacterial staining; Gram-positive (G+ve) bacteria permit entry of crystal violet granules (from stain) into their cell wall to stain purple-black; Gram negative (G-ve) organisms do not take up dye, and stain pale pink

Gram's stain,

n.pr a sequential process for staining microorganisms in which a violet stain is followed by a wash and then a counterstain of safranin. Gram-positive organisms appear violet or blue; gram-negative organisms appear rose pink.

Gram's stain

a staining procedure in which bacteria are stained with crystal violet, treated with strong iodine solution, decolorized with ethanol or ethanol-acetone and counterstained with a contrasting dye, usually safranin. The iodine alters the structure of the cell wall in gram-positive bacteria so that the crystal violet is locked within the cell. Organisms that retain the crystal violet stain are deep purple in color and are classed as gram-positive and those losing the crystal violet stain are classified as gram-negative and are red in color.
References in periodicals archive ?
QC slides for Gram's stain can be made using stock strains of Staphylococcus spp.
The conventional method for performing Gram's stain begins with a thin, air-dried, heat-fixed preparation on a glass slide that is flooded with crystal violet and allowed to sit for at least 30 seconds (see Table 1, above).
The American Society for Microbiology (ASM) provides a comprehensive summary of expected Gram's stain results and the morphologies of different organisms.
Infections caused by mixed organisms do occur; however, a blend of organisms in a Gram's stain may indicate that bacteria unrelated to infection have colonized a site, or that a specimen is contaminated with superficial material.
Additionally, Gram's stain is a key identifier of isolates grown on culture media.
Gram's stain remains one of the most valuable methods we have for identifying isolates accurately and rapidly.
Key words: bacteria, Gram's stain, culture, cloaca, fecal, avian, Hispaniolan Amazon parrots, Amazona ventralis
Many of the bacteria identified by Gram's stains did not result in a corresponding identifiable isolate on culture.
The results of this study suggest that Gram's stains and bacterial culture can be used to provide insight into the gastrointestinal microflora of clinically normal Hispanolian Amazon parrots.
Effects of dietary change on fecal gram's stains in the African grey parrot.
The data for Gram's stains were evaluated with the Shapiro-Wilk test and were found to be not normally distributed; therefore, the median, 10-90 percentiles ([P.