Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The virulence of urease-producing bacteria depends on the ability of urease to degrade urea into ammonia and thereby to alkalinize the urine. Infections caused by urease-producing organisms such as Proteus mirabilis are particularly difficult to manage clinically. We have shown that the layer of glycosaminoglycans at the bladder surface protects against infection by blocking the adherence of bacteria to the epithelium. To determine whether urease-producing urinary pathogens owe their virulence in part to an ability to inactivate the protective effect of the glycosaminoglycan layer, we tested the ability of ammonium chloride to alter bacterial adherence to the normal vesical mucosa. We used an in vivo adherence assay that we have described previously in rabbits. Control animals received sodium chloride adjusted to the same pH as the ammonium chloride. We found that 0.25 M ammonium chloride significantly increases bacterial adherence to normal vesical mucosa as compared to adherence in controls receiving 0.25 M sodium chloride (p less than 0.05). These data suggest that urease plays a hitherto undescribed role in bacterial virulence by altering the antiadherence activity of the glycosaminoglycan layer present at the transitional cell surface.
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PMID:Effect of ammonium on bacterial adherence to bladder transitional epithelium. 637 29

Crystallization of struvite and calcium phosphates was studied in vitro as encrustations on glass rods immersed in synthetic urine, to evaluate the crystallization capacity of Ureaplasma urealyticum and compare it with that of known urease and non-urease-producing bacteria. Inoculation of the synthetic urine with Ureaplasma urealyticum resulted in alkalinization of the synthetic urine and crystallization of struvite and brushite. Inoculation with Proteus mirabilis caused a faster and more pronounced alkalinization as well as crystallization of struvite and apatite. The alkalinization and crystallization caused by Ureaplasma urealyticum and Proteus mirabilis was completely prevented by acetohydroxamic acid, a potent urease inhibitor, linking the crystallization to the urease activity of the microorganisms. When the synthetic urine was inoculated with urease-negative Escherichia coli no alkalinization and no crystallization were seen.
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PMID:Ureaplasma urealyticum-induced crystallization of magnesium ammonium phosphate and calcium phosphates in synthetic urine. 638 69

A spot test for the detection of urease activity was developed and evaluated with 761 strains of gram-negative bacteria. The test was compared with the conventional Christensen urea agar slants and urease test on the Vitek Enterobacteriaceae card (Vitek Systems, Inc., St. Ana, Mo.). Of the 348 strains of the Proteus-Providencia-Morganella group that were urease positive, 327 (94%) yielded positive results within 1 min, and all strains yielded positive results within 2 min. All these organisms also gave a positive urease reaction on the Vitek Enterobacteriaceae card test within 5 h and on the Christensen urea agar slants in 4 to 48 h. All the bacteria that did not hydrolyze urea by these two tests also remained negative by the spot test.
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PMID:Simple spot test for rapid detection of urease activity. 639 23

A urease test for the rapid determination of urea hydrolysis is described in which diluted urea agar concentrate was used in small amounts with dense inoculum of the test organisms. The method was evaluated and compared with Christensen's urea agar slants by using 728 clinical isolates of gram-negative bacteria. Of the 325 strains of urease-positive Proteus-Providencia-Morganella, 282 (87%) gave positive results within 5 min with the rapid test. Urease activity of 97% of these organisms became evident within 30 min. All 287 isolates which showed no urease activity on Christensen's urea agar also remained negative by this test.
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PMID:Rapid test for determination of urea hydrolysis. 639 4

100 cases of urolithiasis in children treated in Pediatric Clinic of National Research Institute of Mother and Child in the period of 1976-1979 were analized . In 93 children the cause of urolithiasis was established. The most of them (31%) are cases of infection induced urinary stones. Among other reasons of urolithiasis the most common are: metabolic reasons in 26%, probably metabolic reasons in 13%, idiopathic oxalic lithiasis in 17% and others in 6%. At the moment of urolithiasis diagnosis in 94 children bacteriological investigations were done. In 54 cases, i.e. 57,4% infections of the urinary tract were found. 57,8% of boys and 62,2% of girls had urinary tract infections. The most frequent bacteria was urease producting Proteus sp. During 3 years of observation urinary tract infections in 67 children were found. Among bacteria causing the reinfections the most frequent were: Pseudomonas aeruginosa (25,4%), Klebsiella sp. (22,4%), Proteus sp. (19,9%) and E. coli (15%). In 9 cases the bacteriological analysis of removed stones were done. In 2 cases bacteria causing the infection were isolated from the stones, since they were not present in urine any more.
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PMID:[Urinary tract infections and urolithiasis]. 642 22

Hyperammonemia with coma, tachypnea, and respiratory alkalosis developed in a 3-year-old boy with prune"-belly syndrome during a urinary tract infection with Proteus mirabilis. Hyperammonemia is thought to have resulted from the production within the massively dilated urinary tract of excessive amounts of ammonia due to bacterial urease, and its subsequent reabsorption into the systemic circulation. The patient rapidly improved following parenteral antibiotic therapy and continuous catheter drainage of the urinary tract.
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PMID:Ammonia encephalopathy secondary to urinary tract infection with Proteus mirabilis. 644 60

Struvite urinary stones are commonly associated with infections by urease possessing bacteria (Proteus). Ureaplasma urealyticum, a genital mycoplasma, is predominantly located in the human genito-urinary tract and produces urease. Its possible role in the formation of infection stones was studied in the rat model described by Friedlander and Braude. Struvite bladder stones were produced in 60% of Sprague-Dawley male rats after infection of ureaplasmas (serotype 1, 2, 3, 7) into the renal medulla. Mycoplasma hominis, another genital mycoplasma, produced bladder stones in only 10% of animals. A kinetic study showed that pure struvite stones appeared into the bladder 4 to 5 days after inoculation and that U. urealyticum did not usually remain viable more than 6 days. Acetohydroxamic acid and doxycycline prevented the formation of the stones.
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PMID:[Experimental magnesium ammonium phosphate lithiasis induced by Ureaplasma in the rat]. 653 Oct 60

The formation of some urinary tract stones (struvite stones) is known to be related to infection by urease-possessing microorganisms, such as Proteus sp. and some other bacteria. Ureaplasma urealyticum, a genital mycoplasma, contains also urease and is predominantly located in the urogenital tract. Its significance in the production of human urinary stones has not yet been elucidated. In this study, 135 human calculi obtained by surgery were analysed chemically and were cultured for the presence of conventional bacteria and U. urealyticum, 51 were ammonium magnesium phosphate stones and contained Proteus (27), E. coli (4), Staphylococcus epidermidis (3), Streptococcus D (2), Pseudomonas aeruginosa (1), Staphylococcus aureus (1), Corynebacterium (1), Candida albicans (1). U. urealyticum was isolated in one patient, from two different calculi (left and right) taken after an interval of fifteen days. Different bacteria were isolated from other calculi (oxalate, uric acid). This findings suggest that Ureaplasma urealyticum should be looked for in struvite calculi.
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PMID:[Comparative bacteriological and chemical analysis of kidney calculi. Apropos of 135 cases]. 653 Oct 61

Certain infection stones are thought to be linked to urease-possessing bacteria such as Proteus sp. Since ureaplasma also contain urease and are predominantly located in the urogenital tract, their possible role in the formation of infection stones was studied in the rat model described by Friedlander and Braude [2]. Infection stones were produced in Sprague-Dawley and Wistar male rats after injection of ureaplasmas into the renal medulla. In Sprague-Dawley rats, six different ureaplasma strains (serotypes 3 and 5 clinical isolates) were able to produce bladder stones. Acetohydroxamic acid, a urease inhibitor, prevented the formation of the stones. There was no difference in urinary pH or the presence of leukocytes, crystals and ureaplasmas in the urine between rats which presented stones and those which did not. Ureaplasmas could be cultivated only very rarely from rat stones. Similarly, no ureaplasmas could be obtained from human stones.
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PMID:Experimental production of bladder calculi in rats by ureaplasma injection. 671 56

In an analysis, by both crystallographic and microbiological methods, of 50 urinary calculi recently removed by surgical operation, 33 proved to be of metabolic origin (mostly calcium oxalate and some uric acid or urate) and 17 of 'infective' origin (struvite, apatite or a mixture of the two). Metabolic stones were usually bacteriologically sterile or contained only small numbers (less than 10(3)/g of stone) of bacteria which did not produce urease, while infective stones always contained urease-producing organisms, usually Proteus mirabilis, in large numbers (greater than 10(5)/g). The combined approach of stone analysis by crystallography and microbiological culture yields more information than conventional techniques on which to base the treatment of urinary calculi and the prevention of their recurrence.
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PMID:Bacteriological and crystallographical analysis of urinary calculi: aid to patient management. 673 6


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