Effect of intestinal flagellate Spironucleus (Hexamita) muris and of dimetridazole on intestinal microflora in thymus-defficient (nude) mice.

Two groups of the intestinal microflora, the lactobacilli and the coliforms, were examined in thymus-deficient (nude) mice during the development of an experimental infection with the intestinal flagellate Spironucleus (Hexamita) muris and during the treatment with dimetridazole. The observed significant decrease in the number of lactobacilli under infection was probably due to the fact that the protozoan parasite fed on the microbes. Dimetridazole (0.3% in drinking water) did not influence the quantity of the lactobacilli but, owing to its selective killing of anaerobes and the lack of their antagonistic activity, a 100- to 1000-fold rise in the number of coliform microbes was observed. No of the drugs tested (dimetridazole, ornidazole, metronidazole, tinidazole, carbimazole BP and chlormethoxy-acridilamino-diethylamino-propanol-dihydrochliorde) was fully successful in the treatment of experimental spironucleosis in mice (Kunstýr, 1978) and it is suggested that recent reports on the therapeutic success of tinidazole in human giardiasis be treated with caution.