The Relation of the Number of Cysts in the Stool Inoculum to the Incidence of Positive Cultures of Endamoeba Histolytica

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  • The Departments of Microbiology and Medicine, The Mount Sinai Hospital, New York City


A direct relationship was noted between the number of cysts of E. histolytica present in stool specimens and the incidence of positive cultures of trophozoites. Positive cultures were invariably obtained when 15 or more cysts per cover slip were counted by direct microscopic examination. The addition of streptomycin or penicillin to the culture medium made it more favorable for the cultivation of specimens containing a small number of cysts. One positive ameba culture was obtained from fifty specimens microscopically negative for cysts of E. histolytica.