Germfree guinea pigs monocontaminated with each of seven species of bacteria were inoculated intracecally with the strain 200 Entamoeba histolytica from ameba-trypanosome cultures. Amebic lesions occurred with each bacterial species tested but lesions developed more rapidly and extensively with some bacterial symbionts than with others. All animals with Bacillus subtilis succumbed to amebic enteritis as did varying percentages of animals with Clostridium perfringens, Staphylococcus aureus, Streptococcus faecalis, and Lactobacillus acidophilus. None of the amebic infections proved fatal in animals with Escherichia coli and a species of Micrococcus during the period of observation. The inflammatory response varied remarkably from an acute reaction with B. subtilis and S. aureus to a typically chronic reaction in germfree animals. The ameba and other bacterial symbionts elicited a basically chronic type of reaction with various degrees of superimposed bacterial inflammation.
Present address: Department of Pathology, New York University Medical Center, New York.