Some Effects of Cultural Associates on the Infectivity of a Strain of Endamoeba Histolytica for the Rabbit
George W. Luttermoser AND
Bruce P. Phillips
National Institutes of Health, National Microbiological Institute, 1 Bethesda 14, Maryland
1. Trophozoites from various cultures of strain 200 Endamoebahistolytica were evaluated as to their infectivity for rabbits.
2. When cultivated with a mixed bacterial flora, strain 200produced a fatal ulcerative amebiasis in about 85 per cent ofthe inoculated animals as compared to 35 per cent when cultivatedwith a single bacterial associate, organism t.
3. Trophozoitesfrom bacteria-free cultures, with T. cruzi asan associate,produced but one infection when inoculated into24 animals.
4. The infectivity of trophozoites of E. histolytica grownwithT. cruzi was restored after the amebae were re-establishedinLER culture with bacteria.
5. In vitro observations demonstratedthat amebae grown in theabsence of bacteria (amebae-T. cruzicultures) became readaptedto an environment with bacteria onlywith difficulty. Hence,this is offered as a possible explanationfor the low infectivityof these amebae when inoculated intracecallyinto rabbits, althoughthe possible influence of encystationon infectivity must beconsidered.