INTESTINAL COLONIZATION OF LABORATORY RATS BY ANAEROBIC OXALATE-DEGRADING BACTERIA - EFFECTS ON THE URINARY AND FECAL EXCRETION OF DIETARY OXALATE

Oxalobacter formigenes, an anaerobic bacterium that degrades oxalate t o CO2 and formate, colonises the intestinal tracts of man and other an imals. In this study, the large intestines of laboratory rats were exp erimentally colonised with a strain of O.formigenes to examine effects of these bacteria on the fate of dietary oxalate. When rats (n = 6) w ere fed a standard rat diet plus 2 per cent sodium oxalate, urinary ox alate excretion was not significantly changed following inoculation an d colonisation with O. formigenes. There was a consistent trend toward s less oxalate excretion in faeces of rats after they became colonised with O. formigenes, but differences between colonised and non-colonis ed states were not significant. In an isotope recovery study, when rat s were orally dosed with [C-14]oxalate, the percentage of C-14 in expi red CO2 from three colonised rats was 10-fold greater than from three non-colonised rats. Although C-14 excretion in faeces was decreased th ree-fold in the group of colonised rats, C-14 activity in the urine of colonised and non-colonised rats was not significantly different. Thu s, although O. formigenes colonised and degraded oxalate in the rat in testinal tract, under conditions of these experiments, this colonisati on did not markedly influence urinary oxalate excretion.