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Query: UMLS:C0034186 (pyelonephritis)
 6,144 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of Corynebacterium renale urease in the establishment of pyelonephritis was studied by the oral administration of acetohydroxamic acid (AHA), a urease inhibitor, to experimentally infected rats. The bacteria were introduced by surgical insertion of a zinc disc containing 1 X 10(6) colony-forming units of C-renale into the urinary bladder whereas sterile discs were implanted in the bladders of the control animals. Daily administration of AHA via the drinking water did not halt the development of pyelonephritis. Larger doses, given by gavage, did accomplish this goal; that is, the pH of the urine was lowered, the number of colony-forming units of C. renale in the kidney was reduced drastically, and pyelonephritic lesions were observed in the kidney by light-microscopic examination. All experimental rats developed cystitis in varying degrees of severity. About 70% of the intact AHA given by gavage was excreted in the urine 24 h after administration of this compound. Rats implanted with a urease-negative mutant of C. renale displayed no signs of pyelonephritis but did develop cystitis.
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PMID:Influence of acetohydroxamic acid on experimental Corynebacterium renale pyelonephritis. 2 38

Intraperitoneal immunization with formalin-killed bacteria as well as previous hematogenous infection with Proteus O3H1 showed a protective effect against hematogenous pyelonephritis in rats when the homologous strain was used. Transfer of hyperimmune antisera protected against hematogenously induced infection. Neither intravesical or intraperitoneal immunization with formalin-killed bacteria nor transfer of urines containing antibodies of the IgG class protected against ascending pyelonephritis when the O3H1 strain was used. Data are presented indicating that a rise of pH might decrease the biological effect of antibodies, suggesting that Proteus urease activity is a virulence factor of importance in this context.
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PMID:Protection against experimental Proteus mirabilis pyelonephritis in rats and significance of immunity. 3 Oct 56

The role of urease in induction of pyelonephritis was studied by treatment of proteus-infected rats with acetohydroxamic acid, a potent inhibitor of urease. Infection was produced by introduction of Proteus mirabilis into the bladder along with a zinc disk. Controls were treated identically but received no acetohydroxamic acid. The number of bacteria per milliliter of urine was the same in both groups. The number of bacteria in the kidneys and the extent of renal damage was much greater in controls. Common enterobacteraceal antigen was not detected in the renal parenchyma of rats treated with acetohydroxamic acid. Treatment with acetohydroxamic acid thus prevented invasion of and damage to kidney tissue without reduction of urinary infection. Thus new evidence was found that the invasive properties of Proteus in the urinary tract are dependent on alkalinization of urine by urease and the resulting damage to the renal epithelium.
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PMID:Role of urease in pyelonephritis resulting from urinary tract infection with Proteus. 23 93

A study was made of 268 cultures isolated from the urine of 263 children suffering from pyelonephritis. Of the total number of different cultures E. coli constituted 79.3 percent; the percentage of the rest varied from 5.2 to 0.4. Examination of 87 urinocultures of E. coli isolated from sick children with the specific immune response showed that the majority of bacterial signs (urease activity, capacity to produce alpha-hemolysin to utilize saccharose and raffinose, to synthesize colicine) failed to correlate with their pyelopathogenicity. The reference to individual serological groups also failed to serve as a sufficient foundation for the separation of these microbes into individual nephropathogenic or pyelopathogenic groups. In experiments with 3H-glucose labeled bacteria there was revealed a marked adhesive capacity in 94 percent of E. coli strains towards the epithelial cells of the RH strain. A positive radioactive label failed to correlate with the presence in E. coli of common pili and with the bacterial agglutinability with the sera K88, K99, and KH-III. The latter pointed to the presence of a factor of unknown nature in the nephropathogenic E. coli strains imparting adhesive properties to bacteria.
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PMID:[Characteristics of microbial cultures in bacteriuria and various data on the immunological reaction in children with pyelonephritis]. 33 27

Urinary stones form as a consequence of urinary supersaturation. Supersaturation occurs as a result of elevated concentrations of urinary solutes. Dietary, metabolic, endocrine, hereditary, and infectious processes alter urinary solute concentrations. Struvite (MgNH4PO. 6H2O) and carbonate-apatite [Ca10(PO4)6CO3] stones form in urine that becomes supersaturated as a by-product of the hydrolysis of urea by the bacterial enzyme urease. Urease-induced stones manifest primarily as branched renal calculi and as bladder calculi. Conventional therapy has usually consisted of surgical removal of the stone combined with a short course of antimicrobial therapy. Such treatment is curative in about 50% of cases. Recurrent stone formation and progressive pyelonephritis occur in those who are not cured. Adjunctive medical treatment with acetohydroxamic acid or hydroxyurea lessens the risk of calculogenesis and decreases growth of residual stones in patients who are not cured by conventional therapy. Patients with urea-splitting urinary infection and renal stones have a major life-threatening disease. The morbidity and expense that result from this disease are great. Long-term (perhaps lifetime) chemotherapy with antimicrobial agents and/or urease-inhibiting drugs combined with judicious and expert surgical intervention can be expected to significantly improve the plight of these unfortunate patients.
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PMID:Urease stones. 38 98

Urinary tract infection with Proteus mirabilis may lead to serious complications, including cystitis, acute pyelonephritis, fever, bacteremia, and death. In addition to the production of hemolysin and the enzyme urease, fimbriae and flagellum-mediated motility have been postulated as virulence factors for this species. We purified mannose-resistant/proteuslike (MR/P) fimbriae and flagella from strains CFT322 and HU2450, respectively. Electron microscopy revealed highly concentrated preparations of fimbriae and flagella. Fimbrial and flagellar structural subunits were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 18.5 and 41 kDa, respectively. N-terminal sequencing revealed that 10 of the first 20 amino acids of the major MR/P subunit matched the sequence of the P. mirabilis uroepithelial cell adhesin N terminus and 11 of 20 amino acids matched the predicted amino acid sequence of the Escherichia coli P fimbriae structural subunit, PapA. In addition, 90 and 80% homologies were found between the first 20 amino acids of P. mirabilis flagellin and those of Salmonella typhimurium phase-1 flagellin and the E. coli hag gene product, respectively. An enzyme-linked immunosorbent assay using purified antigens showed a strong reaction between the MR/P fimbriae or flagella and sera of CBA mice challenged transurethrally with P. mirabilis. A possible role for MR/P fimbriae in the pathogenesis of urinary tract infection is supported by (i) a strong immune response to the antigen in experimentally infected animals, (ii) amino acid sequence similarity to other enteric surface structure, and (iii) our previously reported observation that MR/P fimbriae are expressed preferentially as the sole fimbrial type in human pyelonephritis isolates.
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PMID:Proteus mirabilis flagella and MR/P fimbriae: isolation, purification, N-terminal analysis, and serum antibody response following experimental urinary tract infection. 168 Jan 6

Proteus mirabilis, a common agent of nosocomially acquired and catheter-associated bacteriuria, can cause acute pyelonephritis. In ascending infections, bacteria colonize the bladder and ascend the ureters to the proximal tubules of the kidney. We postulate that Proteus species uses the HpmA hemolysin and urease to elicit tissue damage that allows entry of these bacteria into the kidney. To study this interaction, strains of Proteus mirabilis and P. vulgaris and their isogenic hemolysin-negative (hpmA) or isogenic urease-negative (ureC) constructs were overlaid onto cultures of human renal proximal tubular epithelial cells (HRPTEC) isolated from kidneys obtained by immediate autopsy. Cytotoxicity was measured by release of soluble lactate dehydrogenase (LDH). Two strains of P. mirabilis inoculated at 10(6) CFU caused a release of 80% of total LDH after 6 h, whereas pyelonephritogenic hemolytic Escherichia coli CFT073 released only 25% at 6 h (P less than 0.012). Ten P. mirabilis isolates and five P. vulgaris isolates were all hemolytic and cytotoxic and produced urease which was induced by urea. The HpmA hemolysin is apparently responsible for the majority of cytotoxicity in vitro since the hemolysin-negative (hpmA) mutants of P. mirabilis and P. vulgaris were significantly less cytotoxic than wild-type strains. P. mirabilis WPM111 (hemolysin negative) was used to test the effect of urease-catalyzed urea hydrolysis on HRPTEC viability. In the presence of 50 mM urea, WPM111 caused the release of 42% of LDH versus 1% at 6 h in the absence of substrate (P = 0.003). We conclude that the HpmA hemolysin of Proteus species acts as a potent cytotoxin against HRPTEC. In addition, urease apparently contributes to this process when substrate urea is available.
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PMID:Cytotoxicity of the HpmA hemolysin and urease of Proteus mirabilis and Proteus vulgaris against cultured human renal proximal tubular epithelial cells. 203 63

Proteus mirabilis, a common cause of urinary tract infection, can lead to serious complications including pyelonephritis. Adherence factors, urease, and hemolysin may be virulence determinants. These factors were compared for bacteria cultured from 16 patients with acute pyelonephritis and 35 with catheter-associated bacteriuria and for 20 fecal isolates. Pyelonephritis isolates were more likely (P less than .05) to express the mannose-resistant/Proteus-like (MR/P) hemagglutinin in the absence of mannose-resistant/Klebsiella-like (MR/K) hemagglutinin than were catheter-associated or fecal isolates. Pyelonephritis isolates produced urease activity of 63 +/- 27 (mean +/- SD) mumol of NH3/min/mg of protein, not significantly different from catheter-associated or fecal isolates. Hybridization of Southern blots of P. mirabilis chromosomal DNA with two urease gene probes demonstrated that urease gene sequences were conserved in all isolates. Geometric mean of reciprocal hemolytic titers for pyelonephritis isolates was 27.9; for urinary catheter isolates, 18.0; and for fecal isolates, 55.7 (not significantly different, P greater than .1). Although in vivo expression of urease and hemolysin may not be reliable indexes of virulence, MR/P hemagglutination in the absence of MR/K hemagglutination may be necessary for development of pyelonephritis.
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PMID:Hemagglutinin, urease, and hemolysin production by Proteus mirabilis from clinical sources. 217 24

Accelerated rates of ammonia production by the renal proximal tubule constitute an important adaptation to chronic renal injury. Although serving to maintain net acid excretion, this augmented production of ammonia per nephron results in increased renal cortical levels of ammonia and contributes to progressive renal injury. Ammonia fosters progressive injury via its ability to modify the third component of complement and initiate alternative complement pathway activity. This interaction of ammonia with complement incites inflammation in models of nonimmune chronic renal disease in the rat and may contribute to tissue injury in pyelonephritis involving urease-positive organisms. The long recognized in vivo association between increased renal ammoniagenesis, renal growth, and progressive injury in several models of renal disease has been advanced by the recent demonstration of ammonia as a direct stimulus to growth of renal tubular epithelium in culture. Additionally, evidence from studies of acute ischemic renal injury suggests a contributory role for ammonia in mediating tissue injury in this model. Elevated renal levels of ammonia, therefore, contribute to tubulointerstitial injury primarily through the proinflammatory and growth-promoting properties of ammonia.
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PMID:Role of ammonia in tubulointerstitial injury. 228 94

Microbial ureases hydrolyze urea to ammonia and carbon dioxide. Urease activity of an infectious microorganism can contribute to the development of urinary stones, pyelonephritis, gastric ulceration, and other diseases. In contrast to these harmful effects, urease activity of ruminal and gastrointestinal microorganisms can benefit both the microbe and host by recycling (thereby conserving) urea nitrogen. Microbial ureases also play an important role in utilization of environmental nitrogenous compounds and urea-based fertilizers. Urease is a high-molecular-weight, multimeric, nickel-containing enzyme. Its cytoplasmic location requires that urea enter the cell for utilization, and in some species energy-dependent urea uptake systems have been detected. Eucaryotic microorganisms possess a homopolymeric urease, analogous to the well-studied plant enzyme composed of six identical subunits. Gram-positive bacteria may also possess homopolymeric ureases, but the evidence for this is not conclusive. In contrast, ureases from gram-negative bacteria studied thus far clearly possess three distinct subunits with Mrs of 65,000 to 73,000 (alpha), 10,000 to 12,000 (beta), and 8,000 to 10,000 (gamma). Tightly bound nickel is present in all ureases and appears to participate in catalysis. Urease genes have been cloned from several species, and nickel-containing recombinant ureases have been characterized. Three structural genes are transcribed on a single messenger ribonucleic acid and translated in the order gamma, beta, and then alpha. In addition to these genes, several other peptides are encoded in the urease operon of some species. The roles for these other genes are not firmly established, but may involve regulation, urea transport, nickel transport, or nickel processing.
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PMID:Microbial ureases: significance, regulation, and molecular characterization. 265 66


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