Behavior of axenic IP-106 strain of Entamoeba histolytica in the golden hamster.

Strain IP-106 of Entamoeba histolytica was isolated 12 yr ago from a case of amebic dysentery and has been maintained in axenic culture for the past 11 yr. Hamsters were inoculated intrahepatically, intraperitoneally, and intracecally with 6.5, 5.0, and 8.0 X 10(4) axenic trophozoites, respectively. With the first two routes of inoculation all the animals developed liver abscesses, and most developed amebic metastases to other sites. After intracecal inoculation only 3 out of 6 animals developed abscesses at the primary site and metastases to other sites. Most numerous metastases were obtained following intrahepatic inoculation. Intrahepatic inoculation with 1 and 2 X 10(4) axenic amebae resulted in an increase in the size of the liver abscess for a period of 2 wk and its apparent total resorption by day 17 post-inoculation, accompanied by a corresponding gain of body weight. With 4 and 6 X 10(4) amebae there was a steady increase of the size of the liver abscess and corresponding loss of body weight. High antiamebic indirect hemagglutination titers were observed only on day 17 post infection in animals inoculated with 2, 4, and 6 X 10(4) amebae. The extent of amebic metastases was roughly proportional to the size of the inoculum.