1) It is a solo stain.
2) Simple stainings are usually methylene blue, crystal violet or safranin.
3) Simple staining is adequate to decide bacterial shape.
4) Simple staining is adequate to decide the arrangement characteristics.
Simple staining is when an air dried smear is stained, rinsed, dried and examined using oil immersion lens of the microscope.
Differential Staining
Principle
Gram-negative bacteria have a higher lipid content which is soluble. Therefore it can dissolves in decolorizer.
Gram-positive bacteria have cell walls that have low lipid content. The bacteria will turn less permeable during treatment with decolourizer.
Gram Stain:
Fixation -> Crystal violet -> Iodine treatment -> Decolorization -> Counter stain safranin
Acid-fast Stain
Ziel-Neelson acid-fast stain
Acid-fast: pink
Non-acid fast: blue
Auramine-Rhodamine acid-fast stain
Acid-fast: fluoresce yellow-orange
Non-acid fast: no fluorescence
Principle of Acid-fast stain
Acid-fast stain is used for Mycobacteria since they have a thick, waxy coat.
It make use of carbol fuchsin in the presence of heat to permit the dye to penetrate into the bacterium. Once stained, acid-fast bacteria are resistant to decolorization due to it's thick, waxy coat.
Non-acid fast bacteria are decolorized and take up the methylene blue.
Special Staining
Principle
Capsular Stain
Capsules do not have the same affinity for dyes as other cell components.
Negative staining has a halo around cell against a dark background.
Endospore stain
It has a special resistant, dormant structure formed within a cell that protects the bacteria during adverse environmental conditions.
Flagellar Stain
They have structures of locomotion, which is too tiny to be seen under microscope without staining.
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www.visualunlimited.com
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