Infection of Kittens with Endamoeba histolytica by Direct Injection of Cultures into the Ileum

Abstract

In the course of experiments to test the relative pathogenicity for kittens of a number of strains of Endamoeba histolytica in culture, rectal injection proved unsatisfactory because of the small percentage of kittens which became infected. The technique of rectal injection was simply to withhold food on the day of injection, and inject the sediment from a rich culture by means of a rubber-tipped pipette which was inserted gently through the anus to a distance of about 3 inches. The kitten was then held head downward for a few minutes before being released. In one series the anus was sutured for 24 hours, without producing any better results. A preliminary enema, as used by Kessel 1 was not given because of the desire to avoid even microscopic trauma as far as possible and to avoid early evacuation of the injected material.

Feeding cysts by mouth produced no better results with the one strain with which the method was employed. This method was also impracticable because some strains did not form cysts in culture.

In considering a better route of infection, injection directly into the cecum after laparotomy, as practiced by Rees 2 was not adopted because it was not desirable to pass a needle directly through the wall of the cecum. It was felt that this might create a small lesion in which a few amoebae or bacteria might be left in withdrawing the needle. Faust's method 3 of inoculating dogs directly into the ileum through the anus was not feasible because the colon of the cat is acutely flexed in its upper third, and because there was too much danger of trauma.