Fite
for Acid Alcohol Fast Bacteria
Materials
- Fite’s carbol–new fuchsin
- Acidified Harris’ hemalum
- Fite’s picro fuchsin
- 20% aqueous formalin (1 in 5 dilution of strong formalin)
- 2% hydrochloric acid in 95% ethanol
- 1% aqueous potassium permanganate
- 2% aqueous oxalic acid
Tissue Sample
Formal alcohol was recommended but 5µ paraffin sections of neutral buffered formalin fixed tissue are likely suitable.
Protocol
- Bring sections to water via xylene and ethanol.
- Place sections in carbol-new fuchsin overnight.
- Place in 20% formalin for 5 minutes.
- Decolorise in 2% acid alcohol for 5 minutes.
- Rinse with water.
- Place in 1% potassium permanganate for 2-5 minutes.
- Bleach with 2% oxalic acid for 1 minute.
- Wash with water.
- Counterstain with Harris’ hemalum for 2 minutes.
- Wash with water.
- Stain with Fite’s picro-fuchsin until adequately stained.
- Dehydrate with 95% and absolute ethanols.
- Clear with xylene and mount with a resinous medium.
Expected Results
- Acid alcohol fast organisms – red
- Background – blue
Notes
- Harris’ hemalum should contain acetic acid at 50 mL per liter.
- Note that Fite’s method is not meant to be specific for M. leprae. It is for acid alcohol fast organisms.
- This method was modified by Wade by dewaxing in a mixture of 2 parts rectified turpentine and 1 part liquid paraffin applied twice for 5 minutes each, then blotted and washed repeatedly until the tissue is wetted by the washing. Despite this, the Wade-Fite stain is usually given as this one.
Safety Note
Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.
References
- Gray, Peter. (1954)
The Microtomist’s Formulary and Guide.
Originally published by: The Blakiston Co.
Republished by: Robert E. Krieger Publishing Co. - Humason, G.L., (1967)
Animal Tissue Techniques
W.H. Freeman & Co., San Francisco, CA, USA
