Abstract
As an aid to the microscopic examination of feces for the diagnosis and differentiation of pathogenic amebas, routine cultures should, theoretically, occupy a prominent place in the clinical laboratory. As described in the literature, Dobell's modifications 1 of Boeck and Drbohlav's original media 2 for the cultivation of pathogenic amebas is apparently best suited to routine use, as it furnishes a definite source of assimilable carbohydrate as food for the amebas, and further provides a mild antiseptic (acriflavine) which inhibits the growth of such frequently found bacterial flora as would preclude the obtaining of a positive culture. In obtaining and maintaining a large number of cultures of Endameba histolytica for the past year, many details of producing a uniformly successful medium have been studied. The following method in detail, of preparing these media has seemed to give uniform results:
I. Ingredients of media:
(a) Serum-Ringer solution: Beef or human blood (preferably the latter) is obtained and after clotting is placed for 24 hours in a refrigerator. The serum is pipetted off and mixed with Ringer's solution in the proportion of one part of serum to 8 parts of Ringer's solution. 3 Sterilization is accomplished by passing the fluid through the large type Seitz-Wertz filter. 4 This filtered, sterile, diluted serum is pipetted off with a 50 cc. sterile pipette and placed in sterile flasks, 50 cc. to 100 cc. to each flask. These flasks are kept as cold as possible until ready for use.
(b)Starch: The best kind of starch is rice starch. 5 It possesses small grains, and is not easily hydrolyzed. This is weighed out in 0.2 gm. quantities, placed in small filter paper tubes which are made by rolling a 3 1/2 × 5 cm. piece of thin filter paper about a pencil and in which the starch is kept in place by lightly crimping the ends of the paper tube.
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