| Technique | FAT STAIN |
| Principle | Sudan Black B is a dye that is insoluble inn water but dissolves in fat. Therefore this dye will accumulate in fat globules within a cell |
| Cautions | Blot dry by putting a piece of blotting paper directly on the smear then carefully lift the paper off when the blotting is complete. Do not allow the blotting paper to stick to the smear. |
| Method | 1 Prepare a smear of the
bacteria 2: Allow the smear to dry and heat fix 3: Flood dried fixed smear with Sudan black B stain 4: Stain for 10 minutes 5: Drain off the excess dye 6: Blot dry 7: Add several drops of xylene to clear the excess stain 8: Blot dry 9: Apply safranine for 10-15 seconds 10: Rinse with tap water 11: Air dry 12: Observe stained smear under the oil immersion objective |
| Results | Globules of fat appear blue-black within the red cytoplasm |
| Positive control | |
| Negative control | |
| Reagents | Sudan black B Stain Sudan Black B 0.3 gm 95% ethanol 75 ml distilled water 25 ml Dissolve the Sudan Black B in 95% ethanol then add water and mix thoroughly Safranine |
| Reference |