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Malachite green in stain for Cryptosporidium
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Malachite green in stain for Cryptosporidium


How do you do a malachite green stain for Cryptosporidium?


The Cryptosporidia are stained by carbol fuchsine; malachite green is a counterstain for the background.

This is the procedure I use. (I also do the parasitology here.)  It works fairly well but is not the best diagnostic technique for Cyrptosporidia. There are Meriflour commercial kits that are better than this stain.


This is used on fecal smears.


  Concentrated carbol fuchsine
         10 ml     95% ethyl alcohol
         0.3 gm   Basic fuchsine
         6 ml       Liquid Phenol
         94 ml     Distilled water
         Combine in the listed order.

  10% Sulfuric Acid
        10 ml    Sulfuric acid
        90 ml    Distilled water

  5% Malachite Green
       95 ml     Distilled water
       5 gm     Malachite green


    1. Make a thin smear from the fecal sample.
    2. Dry the smear at room temperature.
    3. Fix the smear in absolute methanol for 2-5 minutes.
    4. Dry at room temperature
    5. Fix briefly in a flame.
    6. Stain with concentrated carbol fuchsine for 20-30 minutes without heating.
    7. Rinse in tap water.
    8. Differentiate with 10% sulfuric acid for 20-60 seconds.
       (Concentrations from 0.25 to 10% can be used; we use 10% sulfuric acid.)
    9. Rinse in tap water.
   10. Counterstain with 5% malachite green for 5 minutes.
   11. Rinse in tap water.
   12. Dry at room temperature.
   13. Examine under oil.
   14. Cryptosporidia will stain bright red with a blue-green background.

Roberta Horner
Penn State University

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