Afb staining Procedure

Ziehl–Neelsen stain

Ziehl-Neelsen staining is a type of acid-fast stain, first introduced by Paul Ehrlich. Ziehl–Neelsen staining is a bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria

                                       

ZN (ZIEHL-NEELSEN)  Stain for AFB (ACID-FAST BACILLI)  Procedure

1.      Fix the smear of the specimen over the glass slide, either by heating or alcohol fixation.

2.      Poor carbol fusion over smear and heat gently until fumes appear. Do not overheat and allow it to stand for 5 minutes, Then wash it off with water.

3.      Pour 20% sulphuric acid, wait for one minute and keep on repeating this stepuntil the slide appears light pink in colour, wash it off with water.

4.      Pour methylene blue, wait for two minutes, again wash with water.

5.      Allow it to air dry and examine under oil immersion lens.

 

Summary of acid-fast stain (Ziehl–Neelsen stain)
Application of	Reagent	Cell colour
		Acid fast	Non-acid fast
Primary dye	Carbol fuchsin	Red	Red
Decolorizer	Acid alcohol	Red	Colorless
Counter stain	Methylene blue/malachite green	Red	Blue

 

                                                                                         

Number of afb count in 10 fields	Report / grading
None	Absent
1 to 2	Positive (+)
2 to 10	Positive (++)
10 to 100	Positive (+++)
Above (>) 100	Positive (++++)

 

                                                                             RANDHIR KUMAR

                                                           RDK PARAMEDICAL STUDENT STUDY