Experimental pyelonephritis. XVII. Enhancement of pyelonephritis by water diuresis following direct inoculation of E. coli in the renal medulla of the rat.

Recently, water diuresis has been shown to promote chronic Escherichia coli bacteriuria following the injection of bacteria into the bladder lumen of rats with normal urinary systems(l). However, maintenance of bacteriuria for periods up to 56 days has not resulted in renal lesions(l,2). Similar effects of water diuresis on bacteriuria have been observed in mice. In this species, however, severe pyelonephritis is a common and prominent finding in animals with bacteriuria of 3 weeks duration(3). Water diuresis, therefore, seemed to increase the susceptibility of the mouse kidney to pyelonephritis. It was remarkable, however, that pyelonephritis did not occur in the rat despite prolonged exposure of the renal papilla to large numbers of bacteria growing in the urine. Since Andriole has demonstrated the protective effect of water diuresis on certain models of pyelonephritis in the rat(4-6) it seemed that one explanation for the difference in the effect of chronic bacteriuria in the mouse and rat was perhaps a difference in the effect of water diuresis on pyelonephritis in the two species. Using the model of direct inoculation of bacteria into the renal papilla to produce pyeloneplhritis Keane was unable to show a protective effect of water diuresis in the mouse(7). The purpose of the present study was to determine the effect of water diuresis on the same model infection (direct papillary inoculation) of E. coli in rats. If rats were protected, it would be possible to explain the dif-