gram staining
DESCRIPTION
Uploaded by Dr. Sara Khalid !TRANSCRIPT
byDr. Khalid Yousuf Memon Lecturer Dept: of Pathology
Gram’s Staining
OBJECT: To study the identification & morphological features of micro-organisms by Grams’ staining
Gram’s Staining
REQUIREMENTS:Glass slide, specimen, wire loop, tripod stand, crystal violet dye, gram’s iodine, spirit, 1/10 % safranin, water, cedar wood oil & Microscope
THEORY:
The Gram stain procedure was originally developed by the Danish Physician Hans Christian Gram to differentiate Pneumococci from Klebsiella Pneumonia. It is also known as “ Differential staining”, as it divides micro-organisms into two main groups i.e. Gram’s +ve and Gram’s –ve micro-organisms.
Gram’s Staining
Crystal violet is a basic dye, it forms a complex with iodine & get fixed permanently in Gram’s +ve organisms. The dye iodine complex is not washed out from these organisms ever. They are not decolorized by spirit use.
Gram’s Staining
This is because these organisms contain thick and multilayered peptidoglycan, while Gram –ve organisms have single layered peptidoglycan, therefore the dye is not fixed permanently in them & is removed by spirit.
Gram’s Staining
Gram –ve organisms loose the dye and become colorless while the Gram + ve organisms retain the colour of crystal violet so when stained with counter stain i.e. 1/10 % Safranin , Gram –ve organisms appear pink in colour while Gram +ve organisms appear violet in colour by retaining the violet colour.
Gram’s Staining
On the basis of Gram’s staining micro-organisms can be divided into four groups; according to their color & shape Gram’s +ve cocci: Streptococci,
Staphylococci. Gram’s +ve bacilli: Corny bacterium
Diphtheria, Clostridia, Bacillus Anthrax. Gram’s –ve Cocci: Neisseria. Gram’s –ve Baccilli: E.Coli, Salmonella,
Shigella, Proteus, Pseudomonas
Procedure1. Take specimen on the wire loop &
spread it on the slide.2. Fix the smear by passing it over
the flame 2-3 times.3. Cover the smear with crystal violet
for 1-2 minutes.4. Wash it & than cover it with Gram’s
staining for 01 minute.5. Wash the smear with spirit till the
blue colour of the slide stops to appear.
Procedure
6. Than wash the slide with water & cover it with 1/10 % safranin red for about ½ minute. Than wash it with water.
7. Allow the slide to dry in air. Put a drop of cedar wood oil.
8. Than see the slide under oil immersion lens.
RESULT Gram +ve organisms appear
violet in colour, Gram –ve organisms appear pink in colour. The epithelial cells and pus cells are also pink in appearance.
Gram +ve Bacilli
Gram +ve & -ve organisms
Gram +ve in chains (S. Pneumoniae)
Gram +ve BacilliClostridium Species
Gram +ve cocciStaph: aureus
Gram +ve Diplococci( Pneumococci)
Gram +ve rods( Diphtheroids)
G+ve & G-ve Bacilli