Experimentally the dependence of E. histolytica on living bacteria in the intestine is well illustrated by the inability of E. histolytica to survive and invade the bowel wall of germ-free guinea-pigs (Phillips, Wolfe, Rees, Gordon, Wright, and Reyniers, 1955) and clinically by the observation that certain antibiotics halt acute amoebic dysentery by inhibiting the growth of intestinal bacteria (Elsdon-Dew, Armstrong, and Wilmot, 1952) but do not affect amoebic liver abscess .The mean size of E. histolytica cultured from bacteria-free human amoebic liver abscess varies according to the bacterial parasites provided (Freedman and Elsdon-Dew, 1958). However, the role of bacteria in the pathogenicity of E. histolytica is obscure; bacteria probably attack the tissues of the host and reduce the resistance or supply essential factors for the growth of amoebae. In the literature, evidence is provided to show that bacteria are necessary for the growth of amoebae in the colon, yet there are no studies to the best of our knowledge to show whether or not any specific bacteria are associated with the growth of amoebae in the intestine.
MATERIAL AND METHODSIn the study of the incidence of bacteria and parasites in 800 cases of dysenteric and non-dysenteric diarrhoea, different types of amoebae were detected on microscopic stool examination in 235 patients (Antia, Chaphekar, Chhabra, Swami, and Borkar, 1961). In 203 of these patients harbouring amoebae, stool was collected for bacterial culture during sigmoidoscopic examination.BACTERIAL STUDIES The material from the colon collected with a spoon through a sigmoidoscope was transferred into nutrient broth and alkaline peptone water. Warm plates of salmonella and shigella agar, desoxycholate citrate agar, and MacConkey agar were kept ready in the incubator at 37°C. Primary plating from broth and peptone water was done immediately on all three plates.After aerobic incubation for 24 hours at 37°C., the plates were observed carefully for pale colonies. At least three such colonies were selected and each was transferred to triple-sugar-iron agar. After 18 to 24 hours' incubation, the results of triple-sugar-iron slopes tentatively identified different organisms and were confirmed with appropriate biochemical and/or agglutination tests.In some cases the plate culture showed greatly altered normal flora with a pure growth of a single organism. In such cases pink, pinkish white, pale grey, green, pale green mucoid or pale-spreading colonies were transferred on appropriate media, including triple-sugar-iron and the organisms identified with biochemical and/or agglutination tests.
RESULTS