On the pathogenicity of Entamoeba histolytica. Part I: The role of bacterial associate on the modification of virulence of E. histolytica.

Of the 3 strains of Escherichia coli used, only Milner A strain was found capable of modifying the virulence of Entamoeba histolytica. None out of twenty-four hamsters inoculated with either 5 X 10(5) of axenically-cultured E. histolytica of NIH: 200 strain, or 1 X 10(7) of Esch. coli (A, B or C strains), was found to have amebic liver abscess. Whereas one out of six hamsters inoculated with the same number of amebae preincubated for 12 hrs with Esch. coli of Milner A strain was found to have abscess. The role of bacterial associate seems to be nothing but provides a more suitable environment for amebae, thus enable them to survive longer and endow them more time to adapt themselves to the given new environment. From liver abscess E. histolytica was recovered and successfully reaxenized. These amebae were capable of producing liver abscess, therefore the virulence seemed to be inheritable.