A challenge procedure based on reflux of Ureaplasma urealyticum to the rat kidney was used to examine the disease-causing potential of this species for the upper urinary tract. Renal infection was detected 8 days after challenge in 90 to 100% of animals exposed to 107 ureaplasmas but was not detected in animals exposed to fewer than 106 microorganisms. Viable microorganisms were recoverable from more than 60% of infected animals throughout a 24-week follow-up period of study. Animals with persistent infection exhibited a humoral response involving immunoglobulin M and immunoglobulin G antibody. These results show that U. urealyticum is capable of giving rise to chronic infection in the kidneys of rats following challenge via the ascending route. Ureaplasma urealyticilm has been recovered from urine aspirated from the bladder and renal parenchyma of patients with reflux nephropathy and declining renal function (1). This fastidious microorganism is the most prevalent mycoplasma in the human genital tract and has been associated with a wide range of genitourinary disorders (1). However, U. utrealyticim has been isolated from the upper urinary tract in only a few studies (1, 11, 12), and its etiologic significance in renal disease is unknown. Therefore, a study was undertaken to examine the disease-causing potential of these bacteria in the upper urinary tract. The ascending route of infection in rats was used to document bacteriologic, immunologic, and histologic features of the hostparasite interaction. The present report describes the bacteriologic and serologic findings. MATERIALS AND METHODS Challenge microorganism. A strain of U. itrealyticlum
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.
Key Takeaways A complete and accurate water service line inventory goes beyond regulatory requirements when used in conjunction with a lead service line replacement program. Absent accurate historical records, it's likely several sources of information will be needed to complete a lead service line inventory. The inventory data must be maintained as a living document so they can be used to help respond if an exceedance occurs.
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