Difficulty in Cultivation of Endamoeba Histolytica.

Abstract

Reports describing the ease with which a number of workers 1 have cultivated E. histolytica have led me to attempt its culture.

Following the method described by Boeck and Drbohlav, 2 material obtained from 19 patients with proved E. histolytica infection was inoculated into their L. E. S. medium. The material obtained from 15 patients showed vegetative forms of ameba only; from 2 patients encysted forms of ameba only; and from 2 patients both encysted and vegetative forms of ameba. The results of these inoculations are embodied in the following table:

Treatment of the ameba containing material with refrigeration, with acid, and with alkali, was done in an attempt to enhance their resistance and to cause them to encyst. In the few instances tried, the treatment proved to be of no value.

Five tubes of media as a minimum were inoculated in each attempt to cultivate ameba from a given patient. Where amebic growth occurred, it was found in at least 2 of the tubes inoculated.

The initial pH of the media varies between 6.8 and 7. The average pH at the end of 24 hours incubation from the cultures from 5 patients was 6.4; at 48 hours 5.6. A pH value of less than 5.4 was never encountered. Protozoal life could not be demonstrated at a pH of less than 6.2. Reinforcement of the buffer value of the serum by the addition of dibasic sodium phosphate did not materially affect the hydrogen ion concentration. The addition of washed human red cells showed no effect on the growth of the ameba or the reaction of the media. The addition of calculated amounts of alkali at short intervals, in the cultures from 2 patients maintained the pH only temporarily but did not affect the growth of the ameba.