How is India ink used for a capsule stain?
Procedure of Capsule Staining India Ink generally works, but it has tiny particles that display Brownian motion that must be differentiated from your bacteria. Nigrosin may need to be kept very thin or diluted. Using sterile technique, add a loopful of bacterial culture to slide, smearing it in the dye.
What staining procedure uses India ink?
Principle of Negative Staining Negative staining requires an acidic dye such as India Ink or Nigrosin.
What are the two different methods of capsule staining?
The first is a wet-mount method using india ink; the capsule is visualized as a refractile zone surrounding a cell. The second is a direct-staining dry-mount method that precipitates copper sulfate and leaves the capsule as a pale blue zone. Both methods are easily performed within approximately 5 min.
Why is it that India ink stains the background instead of the capsule?
This is a negative staining technique that is essentially used to identify the presence of capsules. Because of its acidic nature, India ink (or Congo red, nigrosin) stains the background dark.
Which stain is used for capsule?
Bacterial capsules are non-ionic, so neither acidic nor basic stains will adhere to their surfaces. Therefore, the best way to visualize them is to stain the background using an acidic stain and to stain the cell itself using a basic stain. We use India ink and Gram crystal violet.
Do you heat fix a capsule stain?
Do not heat-fix the smear because this can destroy the capsule and will also cause shrinkage of the bacteria, making a clear area around the cell that can mistakenly be identified as a capsule.
Is India ink positive or negative?
The classic India ink test is positive in only half of cryptococcal meningitis cases, and reliable, rapid cryptococcal antigen (CRAG) testing requires technical expertise and facilities not always available.
What is the mordant in acid fast staining?
During the acid fast stain, heat is used as a mordant to allow the primary stain to penetrate the waxy mycolic acid layer. The heat will prevent the cells from being destained using acid-alcohol. Because these cells hold fast to the primary stain with acid alcohol treatment, they are termed acid fast positive.
What stains are used for capsule staining?
In this type of capsule staining procedure, the primary stain is crystal violet, and all parts of the cell take up the purple crystal violet stain. There is no mordant in the capsule staining procedure. A 20% copper sulfate solution serves a dual role as both the decolorizing agent and counterstain.
Why don’t you heat fix a capsule stain?
Most bacterial capsules are composed of polysaccharide however some genera produce polypeptide capsules. Capsular material is very moist (slimy) and any heating will cause it to shrink – it is for this reason that we will not heat fix the slide before staining.
What is India ink stain used for?
India ink capsule stain is used to demonstrate cell capsules through microscopic examination. This procedure is used to detect presence of encapsualted species, e.g. Cryptococcus neoformans, which causes cryptococcosis in humans.
Why can’t you heat fix a capsule stain?
Which is the best India ink for capsule staining?
India ink is difficult to obtain nowadays; however, nigrosin is easily acquired. A positive capsule stain requires a mordant that precipitates the capsule. By counterstaining with dyes like crystal violet or methylene blue, bacterial cell wall takes up the dye.
Which is the best stain for capsule staining?
Procedure of Capsule Staining Place a small drop of a negative stain (India Ink, Congo Red, Nigrosin, or Eosin) on the slide. Congo Red is easier to see, but it does not work well with some strains. Using sterile technique, add a loopful of bacterial culture to slide, smearing it in the dye.
Can a capsule be stained with crystal violet?
Unfortunately, capsules do not stain well with crystal violet, methylene blue, or other simple stains. This unit describes two methods of capsule staining. The first is a wet-mount method using india ink; the capsule is visualized as a refractile zone surrounding a cell.
Where can I buy India ink for furniture?
Of course, india ink can be bought at any hobby and craft store ready for use. India ink has been used to decorate furniture, especially inlays for quite sometime. Here are some tips: The surface should be completely sealed to prevent absorption of the ink by the wood and migrating to other areas.
