[Gnotobiotic studies on SPF mice in relation to a study of tumor development in the colon after cholecystectomy].

The relation between cholecystectomy and colon carcinogenesis has not been fully elucidated. As bacteria may be involved in the carcinogenic process, we investigated the effect of cholecystectomy and dimethylhydrazine (DMH) administration to SPF NMRI mice with regard to tumour genesis and bacterial colonisation of the intestine. It results from this study that cholecystectomy does not influence tumour genesis and that 6-7 months post operationem and DMH administration tumours and bacteria originally not found in the animals develop: clostridia, eubacteria spec. which cannot be differentiated and E. lentum. Theses changes appear in group II of mice (laparotomy and DMH) and group III (cholecystectomy and DMH), but not in group I (controls). From the results of this study we cannot conclude whether the tumours or the new bacteria appeared first. Biochemical investigations of C. innocuum, C. paraputrificum and C. tertium indicated that these bacteria metabolised bile acids by a specific metabolic step only but not produced carcinogenic substances themselves. If bacteria are involved in tumorgenesis, different species may be involved producing a carcinogenic environment by metabolic chain reactions. We know of such a bacterial collaboration in anaerobic infections.