Staining Of Bacteria

Question 1

Gram staining dev by

Answer 1

Hans Christian gram

Question 2

Diagnostic identification of bacteria in clinical specimen

Answer 2

Gram stain

Question 3

2 ways in which gram staining differentiate bacteria

Answer 3

Based on Chemical and physical properties of their cellwall

Question 4

Principle of gram stain

Answer 4

pH theory
Cellwall theory
Mg ribonucleotide theory

Question 5

pH theory

Answer 5

Cytoplasm of bacteria more acidic
So retain the basic dyes(crystal violet)for longer time
-Iodine serves as mordant
-iodine combine CV iodine complex which get retained in the cell

Question 6

Mg ribonucleotide theory

Answer 6

-gram+ve bacteria has affinity to basic dyes so it takes crystal violet color
By removing it ,bacteria becomes-ve

Question 7

Procedure for mg ribonucleotide theory

Answer 7

1,primary stain-5 sec
2,mordant-5 sec
3,decolorisation-2 sec
4,counter stain -5 sec

Question 8

Procedure of mg ribonucleotide theory in detail

Answer 8

1,smear stained with pararosaniline dyes such as CV for 1min
Rinse it with h20
Cv stains all bacteria in violet
2,gram iodine powdered over the slide for 1min
Slide washed
Gram iodine act as mordant, form dye iodine complex in cytoplasm
3,
Pour few drops of decoloriser
Eg,acetone (2 to 3 sec)
Ethyl alcohol 20nto 30 sec
Acetone alcohol 10 sec
1o stain is removed in gram-ve by decoloriser
Gram +ve retains the stain
4,
2o stain imparts red or pink colour in Gram-ve bacteria

Question 9

Acid fast staining

Answer 9

Discovered paul-ehrlich
Modified by Frans Zeihl and fried rich nelsson
To identify a identify fast organism such as M.microbacterium,M.leprae etc
Fastness due to mycolic acid in cellwall and cellwall integrity

Question 10

Hon to do acid stain

Answer 10

-Microbacteria stained with carbol fuchsin (strong basic dye, basic fuchsin+phenol)
-Acid decoloriser is used after staining
-except acid fast it removes red dye from bg cells,tissue Fibre,or any organism
-bacilli retaining carbol fuchsin,is afb (acid fast bacilli)
-decolorised and hence smear counter stained with MG or MB ,stains BG material which provide good contrast against which red AFB can be seen