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At least 19 recordsLinked to original sources

PubMed1991

Proteus mirabilis biofilm protection against struvite crystal dissolution and its implications in struvite urolithiasis.

Proteus mirabilis biofilm formation, struvite (MgNH4PO4.6H2O) crystal formation and dissolution in an artificial urine mixture were monitored using computer-enhanced microscopy (CEM) and a 1 x 3 mm. glass flow cell. Image analysis showed that P. mirabilis biofilm formation did not occur to any extent at macroenvironment flow rates greater than two mL/h (equivalent to a microenvironment flow rate of less than 5 microns./sec). Essentially, cells attached to glass surfaces, grew slowly and divided. Daughter cells were generally released directly into the medium where they could then presumably colonize other regions. Microcolonies formed by the adhesion of aggregates of cells from the medium, and over time grew into biofilms. Struvite crystallization due to urease activity and pH elevation above neutrality, was preceded by the deposition of organic matter on the glass surface, followed by the appearance of a number of tiny (one to two microns.) crystals. Crystals forming within a biofilm at low dilution rates took on a characteristic twinned or "X-shaped" appearance (crystal habit) indicative of a rapid growth rate. Those forming outside the biofilm took on a more tabular appearance reflecting their slower growth. When the macroenvironment flow rate of artificial urine (initial pH 5.8) in the glass flow cell was increased from two mL/h to four mL/h, struvite crystals not associated with biofilms dissolved within five to 10 min. Crystals entrapped within the P. mirabilis biofilm withstood flow rates up to 200 mL/h presumably due to the maintenance of an alkaline Mg-saturated microenvironment within the biofilm. These observations may suggest a mechanism by which struvite calculi can grow in spite of neutral or acidic urine pH and resist mild acidification therapy.

Bacterial Adhesion↗

PubMed1987

Reduced glomerular filtration rate and hypercalciuria in primary struvite nephrolithiasis.

Struvite nephrolithiasis is caused by infection with bacteria that possess the enzyme urease, and convert urea to ammonia that raises urine pH and crystallizes with magnesium and trivalent phosphate ion. Of the 75 of our 1431 stone patients with struvite stones 52 were women. Struvite stones occurred almost exclusively in women; a minority of women and most men had mixed stones of struvite and calcium oxalate. Increased serum creatinine levels and reduced creatinine clearance were common in patients with struvite stones, not in those with mixed stones; both were rare in calcium stone disease. Men and women with mixed struvite, calcium oxalate stones were hypercalciuric, but women with struvite stones were not. Patients with mixed stones usually had initial symptoms of stone passage, and were less likely to need surgery, including nephrectomy, or to form contralateral stones. Patients with struvite stones usually presented with infection or no symptom, not passage. We conclude that struvite stones occur in two forms. The struvite stone is a disease of women, presumably occurring de novo from infection. The mixed stones occur in both sexes, presumably from secondary infection in hypercalciuric patients who begin with calcium-oxalate stone disease.

Blood Pressure↗

PubMed1987

Feline struvite urolithiasis: factors affecting urine pH may be more important than magnesium levels in food.

Eighteen male cats were fed either a canned complete diet or a commercially available dry pelleted diet or the same dry diet containing 1.6 per cent ammonium chloride. The daily food and water intake of four of these cats was measured. Urine samples were taken at random and the pH and the presence of struvite crystals in their sediment estimated. In some samples in which the pH was less than 7.0, and struvite crystals were absent, the pH was increased to 7.0 and any sediment was examined for struvite. No spontaneous struvite was seen in urine samples (pH 5.8) from cats fed the canned complete diet but when its pH was raised to 7.0, 46 per cent of these samples showed struvite. Cats fed the dry pelleted diet had urine of higher pH (7.55) and 78 per cent of the samples contained struvite crystals. Cats fed this diet supplemented with ammonium chloride had a urine pH of 5.97 and only 9 per cent contained struvite crystals but when the pH was adjusted to 7.0 all the samples showed struvite crystals. Energy intake was similar on all three diets but the intake of dry matter was greater on the dry diets. Liquid water intake was greater on the dry diets but total water intake was greatest on the canned complete diet. The intake of magnesium, calcium and phosphate was greater on the dry diets. It is concluded that urine pH is a more important controller of struvite precipitation than mineral intake.

Animal Feed↗

PubMed1986

Experimental investigation of the genesis of struvite stones in cats.

Infrared spectroscopy of feline urinary stones revealed that struvite was the main constituent in 77.6% of all concrements. However, only in 30.8% (16/52) of struvite stone patients were any infections of the urinary tract detected. Scanning electron microscopical comparison of non-infected feline struvite stones and human struvite concrements which had grown in the presence of infection revealed clear differences. All the feline struvite concrements were of coarse crystalline construction with the crystalline form typical of struvite. Traces of partial solution and stratification were frequently detected on the crystalline surfaces. The human struvite stones whose growth had been accompanied by infection did not display these features; the predominant structures in these concrements revealed very little evidence of any ordered growth. Examination of the urine and calculation of the relative supersaturation showed that where physiological pH values and physiological concentrations of lithogenic substances were present sterile urine can become supersaturated with struvite. The morphological peculiarities of the feline concrements and the results of urinary analysis indicate slow crystalline growth rates. Phases of growth alternate with periods of stagnation. This process may be influenced by dietary factors. In contrast to this, struvite stone formation in the presence of infection is characterised by rapid growth in continually supersaturated urine.

Animals↗

PubMed1987

Feline struvite urolithiasis: fasting reduced the effectiveness of a urinary acidifier (ammonium chloride) and increased the intake of a low magnesium diet.

In three separate experiments nine male cats were fed either a canned complete diet or a commercially available dry pelleted diet or the same dry diet containing 1.6 per cent ammonium chloride for seven days and then fasted for 20 hours. Then ad libitum feeding was continued and urine samples were taken at four-hour intervals for 12 hours and a final sample 12 hours later. Urine pH and the presence of struvite crystals in urine sediment were evaluated. The food and water intake of four of the nine cats was measured at the time of urine collection. After the fast, urine pH was raised, even after feeding the dry diet supplemented with ammonium chloride. A post prandial rise in urine pH was also seen on all three diets. After feeding the dry diet the postprandial peak pH was 7.97 and struvite occurred spontaneously. Urine pH after feeding the dry diet supplemented with ammonium chloride peaked at 7.75 then fell to 6.1 12 hours after the start of feeding. Struvite occurred spontaneously at all times until the pH reached 6.1 but when the pH of urine was raised to 7.0 the struvite crystallised. Urine pH on the canned complete diet peaked at 6.8 then fell to 5.8; struvite did not occur spontaneously but when urine pH was raised to 7.0 struvite crystallised except at the eighth and 12th hour sampling. These data show that fasting initiates a post prandial rise in urine pH and struvite crystalluria even when a normally effective urinary acidifier is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Chloride↗

PubMed1991

Pyrophosphate inhibition of Proteus mirabilis-induced struvite crystallization in vitro.

Struvite (MgNH4PO4.6H2O) crystals, the major mineral component of infectious urinary calculi, were produced in vitro by growth of a clinical isolate of Proteus mirabilis in artificial urine. P. mirabilis growth and urease-induced struvite production were monitored by phase contrast light microscopy and measurements of urease activity, pH, ammonia concentrations, turbidity, and culture viability. In the absence of pyrophosphate, struvite crystals appeared within 3-5 h due to the urease-induced elevation of pH and initially assumed a planar or 'X-shaped' crystal habit (morphology) characteristic of rapid growth. When pyrophosphate was present, initial precipitation and crystal appearance were significantly impaired and precipitates were largely amorphous. When crystals did appear (usually after 7 or 8 h) they were misshapen or octahedral in shape indicative of very slow growth. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) identified all crystals as struvite. Trace contaminates of carbonate-apatite (Ca10(PO4)6CO3) or newberyite (MgHPO4.H2O) were produced only in the absence of pyrophosphate. P. mirabilis viability and culture pH elevation were unaffected by the addition of pyrophosphate, whereas urease activity and ammonia concentrations were marginally reduced. Struvite could also be produced chemically by titration of the artificial urine with NH4OH. If pyrophosphate was present during titration, the same inhibitory effect on crystal growth occurred, so it is unlikely that urease inhibition is important. Lowering of pyrophosphate concentration from 13-0.45 mumol/l did not reduce its inhibitory activity so it is unlikely to act by chelating free Mg2+. We propose that pyrophosphate inhibits struvite growth principally through direct interference with the chemical mechanisms involved in crystal nucleation and growth, because of its effectiveness at very low concentrations.

Ammonia↗

PubMed1990

A simple technique for studying struvite crystal growth in vitro.

Struvite urolithiasis forms as a consequence of a urinary tract infection by urease-producing species of bacteria such as Proteus mirabilis. Ammonia, produced by the enzymatic hydrolysis of urea, elevates urine pH causing a supersaturation and precipitation of Mg++ as struvite (NH4MgPO4). Calcium often precipitates as well, forming the mineral carbonate-apatite (Ca10(PO4)6CO3). We have developed a procedure based on direct observation by light microscopy whereby struvite crystal growth can be quickly monitored in response to chemical changes in urine. As struvite crystals assume a characteristic shape or crystal habit based on their growth rate, the effect of urine chemistry and the action of various crystallization or urease inhibitors on struvite formation can be quickly shown. In addition preliminary effects of alkaline pH, or the presence of toxic compounds on bacteria can also be shown through their loss of motility.

Crystallization↗

PubMed1990

Influence of chondroitin sulfate, heparin sulfate, and citrate on Proteus mirabilis-induced struvite crystallization in vitro.

Struvite crystals were produced by Proteus mirabilis growth in artificial urine, in the presence of a number of naturally occurring crystallization inhibitors. The use of phase contrast light microscopy enabled the effects of added chondroitin sulfate A, chondroitin sulfate C, heparin sulfate, or sodium citrate, on struvite crystal growth rates to be rapidly monitored as changes in crystal habit. Struvite crystals formed as a consequence of the urease activity of P. mirabilis under all chemical conditions. In the absence of inhibitor, early crystal development was marked by large quantities of amorphous precipitate, followed immediately by the appearance of rapidly growing X-shaped or planar crystals. Addition of the glycosaminoglycans, chondroitin sulfate A, chondroitin sulfate C, or heparin sulfate to the artificial urine mixture had no effect on the rate of crystal growth or appearance. When sodium citrate was present in elevated concentrations, crystal appearance was generally slowed, and the crystals assumed an octahedral, slow growing appearance. None of the added compounds had any influence on bacterial viability, pH, or urease activity. It is therefore likely that the inhibitory activity displayed by sodium citrate might be related to its ability to complex magnesium or to interfere with the crystal structure during struvite formation. From these experiments it would appear that citrate may be a factor in the natural resistance of whole urine to struvite crystallization.

Chondroitin Sulfates↗

PubMed1990

Medical dissolution of feline struvite urocystoliths.

The efficacy of a diet designed to facilitate dissolution of feline magnesium ammonium phosphate (struvite) uroliths was evaluated in 30 cases of urolithiasis, sterile struvite uroliths dissolved in a mean of 36 days after initiation of dietary treatment. In 5 cases of urolithiasis, struvite urocystoliths associated with urease-negative bacterial urinary tract infection dissolved in a mean of 23 days after initiation of dietary and antimicrobial treatment. In 3 cases of urolithiasis, struvite urocystoliths associated with urease-positive staphylococcal urinary tract infection dissolved in a mean of 79 days after initiation of dietary and antimicrobial treatment. Dissolution of uroliths in cats fed the treatment diet was associated with concomitant remission of dysuria, hematuria, and pyuria, and reduction in urine pH and struvite crystalluria. In one case, a urocystolith composed of 100% ammonium urate, and in another case, a urolith composed of 60% calcium phosphate, 20% calcium oxalate, and 20% magnesium ammonium phosphate did not dissolve.

Amoxicillin↗

PubMed1975

Constituents of urinary calculi containing struvite.

In a collection of 615 stones containing struvite and in which the sequential deposition of the constituents from the nucleus to the surface had been determined, other substances were found to follow a marked deposition of struvite in 139 cases. In 122, the compound was accompanied by struvite, in 16, struvite was replaced by it and in 1, both types of deposition had occurred in different layers. All urinary stone constituents could accompany struvite and many could replace this compound.

Humans↗

PubMed1986

Struvite crystalluria and urolithiasis in cross Labradors.

Recurrent struvite crystalluria and urolithiasis in a cross-Labrador bitch was studied using a combined Coulter-Counter and scanning electron microscope (SEM) approach. Staphylococcus bacteria were cultured from the patient's urine as well as from the calculi themselves. Urine samples were subjected to particle counting and sizing during active and non-active periods of stone formation. Size distribution curves so obtained were identical as were those derived from sterile and non-sterile specimens. These showed a peak incidence at a diameter of 5 microns. Particle sizes for 6 controls were also determined and showed an even distribution over a much wider range with small peaks occurring at 3, 10, and 20 microns diameters. SEM studies of urine sediments revealed the presence of struvite crystals in all the controls as well as in the stone-former. These occurred in a variety of shapes and sizes but were generally larger in the controls. SEM also revealed intimate admixtures of struvite and apatite in calculi surgically removed from the patient. The results of this study indicate that crystal numbers are of greater significance than crystal size. It is also suggested that Cross-Labradors may be unusually predisposed to struvite crystalluria. The repeated recurrence of struvite urolithiasis in the subject indicates a possible inherent physiological malfunction in the animal's ability to cope with this crystalluria. The absence of a nucleation inhibitor in the stone-former's urine is also postulated.

Animals↗

PubMed1992

In vitro inhibition of struvite crystal growth by acetohydroxamic acid.

Struvite (MgNH4PO46H2O) crystals were produced by Proteus mirabilis growth in artificial urine, in the presence and absence of the urease inhibitor, acetohydroxamic acid (AHA). In the absence of AHA, struvite crystals assumed an "X-shaped" or dendritic crystal habit due to rapid growth along their 100 axis. When AHA was present, crystal growth, as monitored by phase contrast light microscopy, was greatly slowed, and the crystals assumed an octahedral crystal habit. Scanning electron microscopy revealed that crystals grown in the presence of AHA were pitted on their surface. This pitting was absent in control samples. While most of this inhibition by AHA was due to lowered urease activity, some crystal growth inhibition occurred in struvite produced in the absence of urease activity through NH4OH titration of artificial urine. We conclude that while AHA is primarily a urease inhibitor, it may also disrupt struvite growth and formation directly through interference with the molecular growth processes on crystal surfaces.

Animals↗

PubMed1987

Food intake and struvite crystalluria in ferrets.

Four adult, castrated, male ferrets were studied in two similar trials for effects of food intake on variables hypothesized to promote struvite (ammonium, magnesium, phosphate hexahydrate) crystal formation in urine. Struvite crystalluria occurred in three of the four ferrets. Urine pH (UpH) averaged 6.6 for these ferrets. UpH in the ferret without crystalluria was 6.0. By simple linear regression analysis, no relationship was found between the amount of food ingested and the urinary concentration and excretion of magnesium and phosphorous. However, urine osmolality and excretion of both protein and ammonium were correlated to food intake (P less than .05). Ways in which these effects could promote struvite crystal formation are discussed.

Animals↗

PubMed1989

Struvite crystal precipitation by different phenotypes of Yersinia.

Extracellular formation of struvite crystals by Yersinia enterocolitica, Y. frederiksenii, Y. kristensenii and Y intermedia strains was investigated. Precipitation of crystalline structures was found with 19 of the 187 strains tested, its formation being more frequently observed at 25 degrees C than at 37 degrees C. Production of struvite was greater in Y. enterocolitica strains belonging to biotype 1, serogroup 0:7,8 and lysotype Xz, than observed in other phenotypes. Quantitative assay in a liquid medium showed that struvite formation began after 3 d of incubation; production of these crystals increased up to 15 d. Crystalline structures were examined using electron microscopy and their extracellular formation was observed.

Crystallization↗

PubMed2026

Organic Molecules are Involved in Ni-Struvite Biomineralization by Streptomyces mirabilis.

The Gram-positive, filamentous soil bacterium Streptomyces mirabilis P16B-1 has been shown to tolerate high environmental concentrations of Ni. The extremely high metal tolerance is partly provided through biomineralization, observed for both Mg bearing struvite and Ni-struvite where Ni ions replace Mg in the mineral lattice. The minerals showed different morphologies. This led us to assume that excreted substances may have the capacity to influence the mineral formation process that occurs at a distance to the cells. Here, we could show with metabolomics and proteomics studies that 23 metabolites as well as 18 proteins potentially co-precipitate with the minerals. Secreted secondary metabolites reduced in the supernatant after mineralization were identified as ergothioneine, diacetyllegionaminic acid, nevaltophin F, and diaminonaphthalene. The compounds phenylacetaldehyde and margaric acid also reduced after mineral precipitation did not alter mineral macromorphology. In addition, ten proteins that co-precipitated with statistical significance were predicted to be secreted. Among those, a specific nickel binding protein, NikA, was reduced in high amounts from the supernatant upon crystal formation. The potential of secreted organic molecules and proteins to bind specific surfaces of the mineral thereby redirecting crystal growth in a microbially influenced biomineralization process. Implications for biotechnological metal-struvite use are discussed.

Nickel↗

PubMed1992

Struvite stone formation by Corynebacterium group F1: a case report.

Struvite stones are caused by urea-splitting, usually gram-negative, organisms. A case of aggressive struvite stone production caused by Corynebacterium group F1 is reported that responded to the appropriate antibiotic treatment. To our knowledge this organism has never been associated previously with struvite stone formation.

Adult↗

PubMed1976

Dissolution of struvite urinary stones. Experimental studies in vitro.

Previous studies from our laboratory have shown that struvite crystals form primarily as a result of urease-induced alkalinity and supersaturation. In vitro perfusion of struvite crystals with undersaturated urine caused crystal dissolution. The investigations reported herein demonstrate complete dissolution of human struvite urinary stones during 6 weeks of perfusion in vitro with undersaturated human urine. Human hydroxyapatite stones perfused similarly underwent only slight dissolution. A glycoprotein precipitated as the stones dissolved; the pathogenic significance of the glycoprotein is unknown.

Apatites↗

PubMed1979

Dissolution of a struvite nephrolith in a dog.

A large radiodense calculus in the left renal pelvis of a 22-month-old, male Great Dane disappeared one month following surgical removal of two struvite (magnesium ammonium phosphate) calculi from the right renal pelvis. The dog's urine likely became undersaturated with struvite for a sufficient period to permit dissolution of the renal calculus. Several factors may have contributed to the decrease in urine struvite concentration, including eradication of a urease-producing Proteus sp from the urinary tract and induction of polydipsia and compensatory polyuria by oral administration of sodium chloride.

Ammonium Sulfate↗