Experiments with the Use of Carmine Stains for the Detection and Differentiation of Intestinal Protozoa

J. A. Curran
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  1. 1. This paper reviews the previously described methods of staining intestinal amebae and records experiments carried out in an attempt to determine what factors are involved in the staining of cysts and trophozoites with carmine.
  2. 2. It appears that these organisms may be deeply stained in a differential manner in addition to staining of their glycogen contents.
  3. 3. If it is desired clearly to demonstrate glycogen contents the preparations should not be washed in water after carmine staining and the time for the latter may be cut to five minutes.
  4. 4. Of all methods tried, deep-staining with Harris hematoxylin and Best's carmine gave the best results. It was found that if carmine-stained smears were washed in water for ninety seconds, that the cysts still retained a distinctive red color against a decolorized background and could be easily seen under a low-power objective. Nuclear details were clear, although usually not quite equal to the iron-hematoxylin. The chromatoidal bodies stained so clearly against a red background as to be seen under low power. Iodamoeba bütschlii may be found with this technic when missed by other methods.
  5. 5. A more thorough trial is necessary to prove the worth of the Harris-hematoxylin-Bests-carmine technic as a diagnostic routine, but it shows considerable merit. Whether on six routine examinations it will show more or less than the 90 per cent positive results secured by Kessel cannot be predicted without such a trial. In finding certain types of the dysentery ameba and Iodamoeba bütschlii it appears to offer definite advantages.
  6. 6. The technic described takes ninety-one minutes, or about twice as long as the iron-hematoxylin method. Because of the resistant walls of the cysts it seems unlikely that a shorter method will produce satisfactory details. In staining trophozoites only eighty-three to eighty-four minutes is required. Measured by time spent in staining preparations of tissue it is not a long one, and it can be easily carried out by any technician. If it will save time for the diagnostician the extra time in preparation will be well spent.

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