Significance of anaerobic bacteria isolated from the urinary tract. II. Experimental studies

An attempt to cause retrograde urinary tract infection with Bacteroides fragilis (a strain subcultured in artificial media) failed to produce any significant renal infection in rats. Intravenous inoculation with Fusobacterium (a strain subcultured in artificial media) also did not cause demonstrable renal infection in rats. Nor could the anaerobic organism be demonstrated in the kidneys of these animals. Animals receiving Bacteroides (a strain subcultured in artificial media) inoculated directly into the renal medulla developed no renal infection. The anaerobic organism however, continued to be demonstrable in the kidneys of 78 per cent of these animals even on the 3rd day after inoculation. Rabbits receiving Bacteroides (a fresh clinical isolate) which was injected into the subcutaneously fixed kidney with ureteral obstruction all developed overt renal infection. There was also evidence of marked proliferation of the injected anaerobic bacteria and pyuria in these cases.