The materials used in capsule stain include Congo red and Maneval's solution. Congo red is a primary stain that helps to color the background, while Maneval's solution acts as a counterstain to color the bacterial cells. The combination of these two materials helps to visualize the presence of capsules surrounding bacterial cells.
Congo red is the sodium salt of benzidinediazo-bis-1-naphtylamine-4-sulfonic acid (formula: C32H22N6Na2O6S2). It is a secondary diazo dye. Congo red is water soluble, yielding a red colloidal solution; its solubility is better in organic solvents such as ethanol.It has a strong, though apparently non-covalent affinity to cellulose fibres. However, the use of Congo red in the cellulose industries (cotton textile, wood pulp & paper) has long been abandoned, mainly because of its toxicity.Conga Red is an acidic stain primarily used to stain bacterial cells to test for capsules. The Conga Red stain is used to stain a microscope slide background against the colorless cell. Then a basic stain like Maneval's Stain is used to stain the cell. The capsule surrounding some cells will repel the stains and appear colorless against a red (Conga Red) background. The cell inside the capsule will be stained light purple from the Maneval's Stain.
it is some one who is dumb.
Basic dyes: Crystal violet, Methylene blue, Malachite green, Safranin. Acidic dyes: Nigrosin, Congo red
Using Congo red instead of safranin in the Gram stain technique would not provide accurate results. Safranin is essential for counterstaining gram-negative bacteria, whereas Congo red would not differentiate between gram-positive and gram-negative cells due to its staining properties. This would lead to incorrect classification of bacteria in the Gram stain.
Congo Red Stain, NOT WRIGHT STAIN, is the most definitive way to diagnose it. You can find that information on the Mayo Clinic website. Also, if anyone watced the HOUSE t.v. show in September 2006, you probably remember that they used Congo Red Stain to diagnose Amyloidosis for a male patient.
Acidic Congo red is a negatively charged dye that can stain the background of a specimen, giving the appearance of a negative stain. This effect is due to the electrostatic repulsion between the negative charge of the dye and the negatively charged cellular components, causing the dye to be excluded from the cells and stain the background instead.
capsule
When a stain, such as an acid dye, cannot penetrate the outer layers of a microbe, the cell will appear transparent on a colored background. This stain is called a negative or background stain. It is performed by mixing the dye with a suspension of bacteria on a slide and spreading the mixture into a thin layer for viewing. The capsule is a structure surrounding the cell wall that certain bacteria can produce. The ability to form a capsule is genetically and environmentally controlled. Only those microbes with the genes for capsule production have the potential to manufacture this polysaccharide (or polypeptide) surface layer. Special nutrients or other growth factors often are necessary for the genes to be expressed. The role of the capsule is primarily for protection of the bacteria. For example, the capsule affords a seal against dehydration. Many capsules repel white blood cells and thus allow pathogenic invading bacteria to elude one of the primary host defenses. Capsules are not readily stained and therefore are visualized by negative stain techniques. The organisms are prepared as a smear in the presence of an acid dye and allowed to air dry because heat will cause the capsule to shrink. Our procedure will combine a negative stain (which colors the background) and a simple stain to color the bacterial cell. The capsule appears as a colorless layer between the bacterium and the background.
Acidic Congo red stain is a synthetic dye that is based on the structure of azo compounds, which contain an azo group (-N=N-). It is an anionic dye, meaning it carries a negative charge, and is used primarily in histology to detect amyloid deposits in tissues, as it binds to the β-pleated sheet structure characteristic of amyloid proteins. Upon binding, Congo red exhibits a characteristic red color, and under polarized light, it displays a green birefringence, which is indicative of amyloid presence.
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
Congo Red is a dye commonly used in histology to stain cellulose fibers and amyloid proteins red. It is typically prepared as a concentrated solution in distilled water for staining purposes. The cream form may refer to a topical formulation of Congo Red for research or diagnostic purposes.