An experimental study on the pathogenesis of sporadic bacteriuria in the rat.

An experimental model is used in which one ureter of a rat is ligated with the object of forming a hydronephrosis from which urine specimens can subsequently be collected. Ascending urinary infection from the bladder is excluded by the ligation. The investigations with this experimental model showed that growth of intestinal bacteria occasionally occurred in culture of urine obtained from the occluded renal pelvis. Ascending infection being excluded, these bacteria had in all probability entered the renal pelvis via the hydronephrotic kidney. The frequency of infection seemed to increase with age. Whedronephrotic kidney. The frequency of infection seemed to increase with age. When intravenous injection of E. coli was added to the standard experiment, substantial growth of these bacteria was found in the left upper urinary tract in 16 out of 17 animals thus treated.