Bacteriologic and serologic findings in experimental pyelonephritis caused by Ureaplasma urealyticum

Pickering, William J.; Birch, Douglas F.

doi:10.1128/iai.57.4.1235-1239.1989

Cited by 4 publications

(4 citation statements)

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“…Although Ureaplasma is not a natural pathogen of rodents, experimental infection of the rodent urinary tract with Ureaplasma has been established by inoculation into the bladder and/or renal pelvis (10,22,23,27,28). Experimental infection in different rat strains produces a wide spectrum of disease ranging from mild inflammation to predominantly hyperplastic lesions of the bladder with varying degrees of pyelonephritis and urolithiasis (10,22,23,27,29). These studies were done under different conditions with different isolates of Ureaplasma; therefore, direct comparisons cannot be made.…”

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Rat Strains Differ in Susceptibility to Ureaplasma parvum -Induced Urinary Tract Infection and Struvite Stone Formation

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Individuals with struvite uroliths are susceptible to recurrent urinary tract infections (UTI), sepsis, and renal disease. Unfortunately, little is known about the host-specific factors that predispose to this disease. In order to develop a rodent model that can address this problem, we inoculated female Fischer 344 (F344), Lewis (LEW), Sprague-Dawley (SD), and Wistar (WIS) rats with a host-adapted strain of Ureaplasma parvum. Animals were necropsied at 2 weeks postinoculation; 100% of F344, 42% of SD, 10% of LEW, and 10% of WIS rats remained infected. Severe bladder lesions and struvite calculi were seen in 64% of F344 rats; in other rat strains, bladder lesions were mild or absent. F344 rats with struvite uroliths had the highest urinary levels of proinflammatory cytokines, such as GRO/KC, interleukin-1␣ (IL-1␣), and IL-1␤. F344 rats without struvite stones at necropsy had milder bladder lesions and significantly lower urinary levels of proinflammatory cytokines but a more prominent inflammatory response than did other rat strains. Based on our results, struvite stone formation is linked to a robust inflammatory response that does not resolve UTI but instead promotes damage to surrounding tissues.Although struvite calculi constitute only 2 to 3% of stones that are analyzed, they create greater clinical complications, such as sepsis and renal disease (30), than any other stone type. Not all factors that contribute to struvite stone formation are known, but urinary tract infections (UTI) are usually a predisposing factor. Infections with urease-producing bacteria, such as Klebsiella, Proteus, Pseudomonas, and Ureaplasma, significantly increase the risk of struvite formation due to increases in urine pH and direct damage of the uroepithelium by ammonia (13, 29).Host-specific factors also increase the risk of struvite formation during a UTI episode. Obvious examples of host-specific factors are anatomic anomalies of the urogenital tract that disrupt the capacity to void urine (13, 29). However, in most patients a predisposing factor cannot be identified, and the underlying cause of struvite stone formation remains unclear. Since UTI is a prerequisite for struvite stone formation, risk factors for UTI also need to be considered. In women, colonization of the vagina with potential uropathogens combined with impaired host defense mechanisms increases the risk of UTI (7,32,38). In addition, genetic factors have been postulated to play a role in susceptibility to UTI (37).Although ureaplasmas are not the only urease-producing bacteria known to cause struvite calculi (11,12,14), they are uniquely considered opportunistic pathogens because they can be readily isolated from the lower urogenital tract of healthy humans as well as individuals with disease (26, 39). Epidemiological studies show that women have much higher Ureaplasma colonization rates (5) as well as higher rates of infection-induced calculi that are culture positive for Ureaplasma (19) than do men. Since most diseases caused by mollicutes are influenced by a...

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Rat Strains Differ in Susceptibility to Ureaplasma parvum -Induced Urinary Tract Infection and Struvite Stone Formation

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“…With this in mind, we used a rat-ascending pyelonephritis model to examine the disease-causing potential for the kidney of U. urealyticum. The bacteriologic and serologic findings were reported previously (14), and we now set out the histologic and biochemical results.…”

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“…Kidney culture. Homogenates were cultured for U. urealyticum and other bacteria as described previously (14).…”

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Biochemical and histologic findings in experimental pyelonephritis due to Ureaplasma urealyticum

1990

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Ureaplasma urealyticum has previously been shown to be capable of persisting in the rat kidney for up to 6 months following a single reflux challenge. We examined kidney tissue from infected animals for evidence of renal damage by using standard cytochemical and immunoenzyme methods. We also monitored changes in renal function during a 6-month study period with standard biochemical assays of plasma and urine. Histologic examination showed tubular atrophy, interstitial fibrosis, and a mononuclear infiltrate in proportion to ureaplasma counts from renal tissue. The most severe damage was accompanied by hyaline cast formation within tubules which gave rise to the typical thyroidlike appearance of chronic pyelonephritis involving conventional urinary pathogens. Macroscopic renal scarring occurred in some animals. Although damage to the renal medulla was moderate to severe, only minor changes were seen in the cortex, and glomeruli were invariably spared. Biochemical tests of renal function showed similar changes in infected and uninfected animals during the study period. Interstitial inflammation was characterized by a mononuclear cell infiltrate in which polymorphonuclear leukocytes were not conspicuous. It is evident that U. urealyticum is capable of producing chronic pyelonephritis in the rat after a single reflux challenge. The results of this study have obvious implications for the pathogenicity of these bacteria in human pyelonephritis.

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Suppurative Nephritis and Pyelonephritis, Rat

Duprat¹,

Burek²

1986

Urinary System

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Bacteriologic and serologic findings in experimental pyelonephritis caused by Ureaplasma urealyticum

Cited by 4 publications

References 13 publications

Rat Strains Differ in Susceptibility to Ureaplasma parvum -Induced Urinary Tract Infection and Struvite Stone Formation

Rat Strains Differ in Susceptibility to Ureaplasma parvum -Induced Urinary Tract Infection and Struvite Stone Formation

Biochemical and histologic findings in experimental pyelonephritis due to Ureaplasma urealyticum

Suppurative Nephritis and Pyelonephritis, Rat

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