Bacteriological STAIN *Stains is any colored, organic compound, that used to stain - PowerPoint Presentation

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Bacteriological STAIN

*Stains is any colored, organic compound, that used to stain

tissues, cells, cell components, cell contents, or microorganisms.

*The stain may be

natural or synthetic

.

*The object stained is called the

substrate

.

*Staining facilitates the observation of a substrate by introducing

differences in optical density

or in

light absorption

between the substrate and its surroundings or between different parts of the same substrate

ACIDIC

:

Have negative charge so they bind to positively charged cell structures like some proteins.Ex: Nigrosine, Picric acid, Eosin, Acid fuschin, India ink BASIC: Have Positive charge so bind to negatively charged molecules in cell like cell wall.Ex: Crystal Violet, Methylene Blue, Safranin , basic fuschin.NEUTRAL: Both positively and negatively charged imparts different colors to different components.Ex: Geimsa’s stain, Leishman’s stain, Wright’s stain.

According to nature of stain

Bacterial smear

Classification of stains according to the purpose of use

1-Simple stains:

Crystal violet, Methylene blue and Carbolfuchsin.

Results:

All cells have the same color

Morphology – cocci/spherical / rod.Arrangement – clusters/chains.

2-Differential stains:

*more than one stains are involved in the staining proses and stains react differently with different cell types.

Gram staining

Gram

Staining

Procedure

(CV-I) complex

Gram staining principles

-

Results for gram stain G –

ve

and G +ve

Factors affecting the efficiency of Gram staining process

1- Bacterial smear thickness

2- Smear fixation 3- Concentration and freshness of reagents may affect the quality of the stain4- The nature and age of the bacterial culture5- The washing waterFalse results G -ve may appear as G +veG+ ve may appear as G-ve

Acid-fast organisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex lipids

Acid-fast stain

PRINCIPLE OF

ZIEHL-NEELSEN STAIN

Carbolfuchsin, is lipid-soluble and contains phenol, which helps the stain penetrate the cell wall**

1

2

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How the Acid fast

bacteria appear

SPECIAL

STAINS 1- Capsules Stain (Negative stain)

Nigrosine

India ink

Spores Stain

Flagella Stain

Leifson’s stain Malachite green