Hematogenous Pyelonephritis in Rats. I. Its Pathogenesis When Produced by a Simple New Method 12

Abstract

The study of experimental pyelonephritis has been generally restricted to that form of the disease which develops after ligation of the ureter (1-3). When pyelonephritis is complicated by ureteral ligation, however, a clear distinction cannot be made between the effects of urinary obstruction and those of infection. We have attempted, therefore, to establish experimental pyelonephritis in the absence of hydronephrosis and have succeeded by subjecting rats to a simple new technique requiring only two steps: 1) Injection of bacteria into the blood and 2) Massage of the kidneys through the intact abdominal wall. This method has provided an experimental model which appears to reproduce closely that form of human pyelonephritis occurring in patients with no manifest hydronephrosis. In addition, it dispenses with the cumbersome surgical procedures previously required for the production of experimental pyelonephritis.This report describes the pathogenesis of pyelonephritis in rats when renal massage is combined with the inoculation of strains of Escherichia coli isolated from human infections. METHODSI. The effect of renal massage on the incidence of pyelonephritis in rats inoculated uith E. coli Sprague-Dawley rats weighing 150 to 200 gm. were divided into two groups of 15 each, and inoculated intracardially with 0.5 ml. of an 18-hour tryptose broth culture of E. coli, or approximately 10' living bacterial cells as determined by plate counts. This strain of E. coli had been isolated from the blood of a patient a few days before the experiment and had been subcultured only twice. Immediately after the bacterial inoculation, one group of 15 rats were subjected to bilateral renal massage. The kidneys of each rat were grasped by thumb 1 Aided by research grant from Public Health Service, H-1955. 2 Presented in part at the 27th Annual Meeting of The Central Society for Clinical Research, October 30, 1954. and forefinger through the intact abdominal wall (Figure 1) and gently but firmly massaged during ether anesthesia for exactly 5 minutes. In order to maintain a uniform degree of pressure on the massaged kidneys, each period of 5 minutes was divided between two of us instead of confining the total period of massage for each animal to one of several persons. The 15 rats in the second group were anesthetized under ether for 5 minutes but their kidneys were not massaged. The kidneys of a third group were massaged for 5 minutes under ether anesthesia but the rats were not inoculated with bacteria. This third group also served as controls for the experiments in section 3b and are described there.Within 48 hours, 4 rats in each group had died after the inoculation of E. coli. The survivors recovered fully and appeared in excellent condition. At the end of two weeks, the rats were sacrificed by exposure to ether and exsanguination. Approximately 1.0 ml. of blood was divided between trypticase soy broth and blood agar for culture and 0.5 ml. was used for determining urea nitrogen. The kidneys were examined grossly and then each...

Increased Susceptibility to Pyelonephritis During Acute Hypertension by Angiotensin Ii and Norepinephrine*

“…Furthermore, as expected from the gross appearance of the lesions at 1 and 2 weeks, the histological data indicated that the rare lesions in Group II kidneys were small and showed minimal extension through the kidney parenchyma. whereas lesions in Group I presented the typical wedge-shaped appearance described in previous studies (13,16 fold. Blood levels of E. coli were virtually identical in both groups at 24 hours and were negative by 1 week.…”

Preparation and Biological Properties of a Chemically Modified Escherichia Coli Endotoxin of High Immunogenic Potency and Low Toxicity

“…Immediately afterward, each rat was inoculated intracardially with 0.5 ml of an 18-hour culture in trypticase soy broth containing approximately 109 cells per ml of the same E. coli strain from which the endotoxin had been extracted. The kidneys of the animals were massaged for 5 minutes through the intact abdominal wall in order to produce pyelonephritis (27). Seven days later all surviving rats were sacrificed by exsanguination and exposure to ether.…”

Altered clinical and histological features of male MM mouse pyelonephritis associated with a change in its microbiology

“…Furthermore, many experimental techniques induce haematogenous pyelonephritis, 43 whereas most natural infections are ascending in nature. The interventional techniques have included administration of renal toxins (Yamauchi et at., 1961), potassium depletion (Woods et at., 1960), electrocautery (Rocha et at., 1958), renal massage (Braude, Shapiro & Siemienski, 1955), ureteric occlusion (Lepper, 1921), occlusion of renal arteries (Goldblatt et at., 1934), challenge with highly virulent bacteria (Cotran et at., 1963) and foreign-body implantation (Miller et at., 1956). The routes of bacterial challenge have included intravenous (Helmholz, 1934), intracardiac (Pitsch, Hebert &Carey, 1962) andintra-urethral (Hepinstall, 1965) injection, and the introduction of infection directly into the bladder (Brooks, Lyons & Braude, 1974) or kidney (Alderman & Freedman, 1963).…”