This stain is useful for the detection of motile trophozoites of Entamoeba species.
Acridine orange (acetate buffered)
The addition of acridine orange to a faecal concentrate highlights the chromidial bars of Entamoeba coli, Entamoeba histolytica/ dispar and Entamoeba hartmanni, which fluoresce bright green.
Auramine phenol (lempert)
1. Make faecal smears as for ZN and fix in methanol.
2. Stain with Auramine-Phenol (Lemperts) for 10 – 15 min.
3. Rinse thoroughly in tap water.
4. Decolourise in acid alcohol (as for ZN).
5. Rinse thoroughly in tap water.
6. Counterstain with 0.1% potassium permanganate for 30 sec.
7. Rinse thoroughly in tap water, allow to air dry. Do not blot dry, many brands of blotting paper will fluoresce!
Results in Oocysts appearing as bright yellow discs against a dark background.
Field’s Stain – Solution A and Solution B
N.B. Both solutions are ready for use and should not be diluted.
This technique is a rapid Field’s stain method, which enables rapid staining of fixed thin films of various clinical samples. This particular method is very useful for staining films of unformed faeces, faecal exudates, duodenal aspirates etc.
1. Make a thin film of faeces/exudate and allow to dry.
2. Fix in methanol for 1 min.
3. Flood slide with 1 ml of Field’s Stain B .
4. Immediately add an equal volume of Field’s Stain A mix well on slide and allow to stain for 1 min.
5. Rinse well in tap water and drain dry.
6. Examine the film using the oil immersion objective and immersion oil.
Parasite nuclei and structures containing chromatin – red
Cytoplasm – bluish-grey
Leucocyte nuclei – purple
Yeasts and bacteria – dark blue