The ecology and pathogenicity of urease-producing bacteria in the urinary tract

Metabolic Evaluation and Recurrence Prevention for Urinary Stone Patients: An EAU Guidelines Update

BACKGROUND AND OBJECTIVE

The aim of this review was to define patients who are at high risk of recurrence of urolithiasis, to delineate diagnostic and therapeutic algorithms for each type of stone, and to clarify general guidelines and recommendations for prevention of recurrence.

METHODS

A professional research librarian carried out literature searches for all sections of the urolithiasis guidelines, covering the timeframe between 1976 and June 2023.

KEY FINDINGS AND LIMITATIONS

For every patient with urolithiasis, an attempt should be made to analyse the stone. Patients should be given general instructions on how to prevent recurrence, including adequate fluid and calcium intake, and low consumption of sodium and protein. Identifying and correcting the causative factors is a cornerstone in preventing the recurrence of urolithiasis. Diagnostic and therapeutic algorithms by stone composition are available. Every patient should undergo baseline metabolic screening, while patients with calcium stones, who are at high risk of relapse and complications, should undergo extensive metabolic screening with two 24-h urine collections and should receive targeted therapy. Patients with uric acid, infection, or cystine stones are at high risk of relapse. All patients at high risk of recurrence should be closely monitored, especially those not complying with therapy in the long term.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Metabolic stone evaluation and patient follow-up are highly recommended to prevent urolithiasis recurrence.

PATIENT SUMMARY

We reviewed the evidence for proper evaluation of patients with urinary and stones and the treatment options for preventing stone recurrence. It is essential to determine the type of stone and to carry out specific blood and urine tests for planning the best treatment course for each patient.

Understanding the role of zinc ions on struvite nucleation and growth in the context of infection urinary stones

Taking into account that in recent decades there has been an increase in the incidence of urinary stones, especially in highly developed countries, from a wide range of potentially harmful substances commonly available in such countries, we chose zinc for the research presented in this article, which is classified by some sources as a heavy metal. In this article, we present the results of research on the influence of Zn2+ ion on the nucleation and growth of struvite crystals-the main component of infection urinary stones. The tests were carried out in an artificial urine environment with and without the presence of Proteus mirabilis bacteria. In the latter case, the activity of bacterial urease was simulated chemically, by systematic addition of an aqueous ammonia solution. The obtained results indicate that Zn2+ ions compete with Mg2+ ions, which leads to the gradual replacement of Mg2+ ions in the struvite crystal lattice with Zn2+ ions to some extent. This means co-precipitation of Mg-struvite (MgNH4PO4·6H2O) and Znx-struvite (Mg1-xZnxNH4PO4·6H2O). Speciation analysis of chemical complexes showed that Znx-struvite precipitates at slightly lower pH values than Mg-struvite. This means that Zn2+ ions shift the nucleation point of crystalline solids towards a lower pH. Additionally, the conducted research shows that Zn2+ ions, in the range of tested concentrations, do not have a toxic effect on bacteria; on the contrary, it has a positive effect on cellular metabolism, enabling bacteria to develop better. It means that Zn2+ ions in artificial urine, in vitro, slightly increase the risk of developing infection urinary stones.

Chemical characterization, anti-struvite crystal, anti-inflammatory, analgesic, and antidepressant activities of Papaver rhoeas L. root and leaf extracts

ETHNOPHARMACOLOGICAL RELEVANCE

Papaver rhoeas L. (P. rhoeas) is used to treat a wide range of pathologies. But there is no data on the anti-struvite, anti-inflammatory, analgesic, and anti-depressant effects of root and leaf extracts from this medicinal plant.

AIM OF THE STUDY

This study aimed to chemically characterize and determine the antidepressant, analgesic, anti-inflammatory, and anti-struvite activities of the root extract (RE) and leaf extract (LE) of P. rhoeas, a wild plant.

MATERIALS AND METHODS

The extraction of secondary metabolites and phytochemical screening were carried out using standard methods. The anti-struvite effect of our samples was assessed by Fourier transform infrared spectroscopy (FT-IR) and microscopic observation. For the anti-inflammatory impact, we used the carrageenan-induced paw edema technique in rats. To assess the analgesic effect of the extracts, we recorded the resulting abdominal contraction after intraperitoneal (IP) acetic acid injection. Finally, we assessed the antidepressant effect by conducting the Forced Swimming Test (FST).

RESULTS

Phytochemical screening results revealed the presence of phenols, flavonoids, saponins, tannins, coumarins, terpenoids, and alkaloids. Extraction results confirmed that our extracts were rich in secondary metabolites. Both P. rhoeas extracts limited struvite crystal development by reducing the size and number of crystals, as indicated by FT-IR analysis and microscopic observation. Additionally, the anti-struvite effects of the LE sample were greater than those of the RE sample. The results of the anti-inflammatory capacity of our extracts demonstrate the maximum inhibition of carrageenan-induced edema following 6 h (T6) of injection, ranging from 72.73 ± 7.7% for LE (400 mg/kg) to 95.45 ± 6.42% for the RE sample (400 mg/kg). On the other hand, the results for analgesic activity showed that the number of abdominal contractions in rats treated with RE and LE ranged from 11 ± 1.73 for RE (400 mg/kg) to 18 ± 1.50 for LE (200 mg/kg), while that of aspirin was 10.33 ± 0.57. Furthermore, the FST results show that the immobility time in rats treated with RE and LE varied from 91.98 ± 4.24 s for LE-treated rats (300 mg/kg) to 123.54 ± 7.83 s for RE-treated rats (150 mg/kg).

CONCLUSION

Based on these results, the roots and leaves of the studied plant can be considered a significant source of biologically active molecules for use in the pharmaceutical industry.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Analysis of lower urinary tract signs and bacteriuria in cats with subcutaneous ureteral bypass systems

Objectives

Distinguishing bacterial cystitis from subclinical bacteriuria is necessary for feline treatment protocols and antimicrobial stewardship. This can be challenging in cats with subcutaneous ureteral bypass (SUB) systems because they may present with lower urinary tract signs without bacteriuria. We investigated the relationship between positive urine culture and lower urinary tract signs in cats with SUBs, including factors associated with each.

Methods

Clinical records were retrospectively reviewed to identify cats presenting with ureteral obstruction that underwent placement of a SUB device(s). The relationship between a positive urine culture and lower urinary tract signs was determined by chi-squared analysis. Univariable and multivariable logistic regression models were performed to identify factors associated with positive urine cultures and lower urinary tract signs.

Results

Two hundred and thirty visits were recorded for 61 cats, with 36 of 230 (16%) positive cultures in 21 of 61 (34%) cats. Lower urinary tract signs were documented at 97 of 230 (42%) visits, with 37 of 61 (61%) cats demonstrating lower urinary tract signs at some point. No relationship was found between culture results and lower urinary tract signs. Risk factors for a positive culture were higher urine pH, higher urine white blood cells and the presence of bacteriuria on microscopy. Risk factors for lower urinary tract signs were younger age and being a purebred cat (vs. non-purebred).

Conclusions

A high proportion of cats with SUBs exhibited sterile lower urinary tract signs, making differentiation between bacterial cystitis and subclinical bacteriuria difficult. This highlights the need for clearer guidelines on when to treat bacteriuria in cats with SUBs.

Proteomics of Paracoccidioides lutzii: Overview of Changes Triggered by Nitrogen Catabolite Repression

Members of the Paracoccidioides complex are the causative agents of Paracoccidioidomycosis (PCM), a human systemic mycosis endemic in Latin America. Upon initial contact with the host, the pathogen needs to uptake micronutrients. Nitrogen is an essential source for biosynthetic pathways. Adaptation to nutritional stress is a key feature of fungi in host tissues. Fungi utilize nitrogen sources through Nitrogen Catabolite Repression (NCR). NCR ensures the scavenging, uptake and catabolism of alternative nitrogen sources, when preferential ones, such as glutamine or ammonium, are unavailable. The NanoUPLC-MSE proteomic approach was used to investigate the NCR response of Paracoccidioides lutzii after growth on proline or glutamine as a nitrogen source. A total of 338 differentially expressed proteins were identified. P. lutzii demonstrated that gluconeogenesis, β-oxidation, glyoxylate cycle, adhesin-like proteins, stress response and cell wall remodeling were triggered in NCR-proline conditions. In addition, within macrophages, yeast cells trained under NCR-proline conditions showed an increased ability to survive. In general, this study allows a comprehensive understanding of the NCR response employed by the fungus to overcome nutritional starvation, which in the human host is represented by nutritional immunity. In turn, the pathogen requires rapid adaptation to the changing microenvironment induced by macrophages to achieve successful infection.

Papaver rhoeas L. stem and flower extracts: Anti-struvite, anti-inflammatory, analgesic, and antidepressant activities

The Papaver rhoeas L. (P. rhoeas) plant, which belongs to the Papaveraceae family, is also used as food and is exploited to treat several health problems. The purpose of this research is to determine the anti-struvite, anti-inflammatory, analgesic, and antidepressant effects of the stem extract (SE) and flower extract (FE) of the plant P. rhoeas. We used polarizing microscopy and Fourier transform infrared spectrometry (FT-IR) to evaluate the anti-struvite effect of our plant. The edema approach induced by the carrageenan molecule was used to study the anti-inflammatory impact of our extracts. The analgesic test was determined by calculating the number of abdominal contractions induced by the intraperitoneal (IP) administration of acetic acid. To evaluate the antidepressant effect of our extracts, we used the forced swimming test (FST). According to the results of the secondary metabolite extraction, both extracts contained high contents of secondary metabolites, while the results of the screening test showed that flavonoids, alkaloids, phenols, tannins, coumarins, saponins, and terpenoids were present. The result of struvite crystallization inhibition observed by polarizing microscopy and FT-IR shows the inhibition of struvite crystal aggregation by SE by decreasing the amount and size of crystals in a manner similar to cystone. The results of anti-inflammatory activity show maximum inhibition of edema after six hours of carrageenan injection in rats (T₆) for all extracts, with a maximum value of 86.36% for SE at the dose of 200 mg/kg. Regarding the analgesic effect of our plant, the lowest number of abdominal contractions was observed in rats treated with SE at a dose of 400 mg/kg. The FST results show that the lowest immobilization time was observed in rats treated with FE at a dose of 400 mg/kg. The results obtained show that the flowers and stems of P. rhoeas can constitute a rich source of bioactive molecules with potential pharmaceutical applications.

Transient distal renal tubular acidosis with nephrogenic diabetes insipidus after general anaesthesia in a dog

A 3-year-old, 3.5 kg, female spayed Pomeranian was referred due to persistent vomiting, anorexia, polyuria and polydipsia, 7 days after receiving general anaesthetic for a medial patellar luxation correction. Physical examination revealed lethargy, tachypnoea and 7% dehydration. Complete blood count and serum chemistry results were unremarkable, and venous blood gas analysis revealed hypokalaemia and hyperchloraemic metabolic acidosis with a normal anion gap. Urinalysis revealed a urine specific gravity (USG) of 1.005, pH of 7.0 and proteinuria, and the bacterial culture was negative. Based on these results, the dog was diagnosed with distal renal tubular acidosis, and potassium citrate was prescribed to correct metabolic acidosis. In addition, concurrent diabetes insipidus (DI) was suspected because the dog showed persistent polyuria, polydipsia and a USG below 1.006 despite dehydration. After 3 days of initial treatment, acidosis was corrected, and vomiting resolved. Desmopressin acetate and hydrochlorothiazide were also prescribed for DI, but the USG was not normalized. Based on the insignificant therapeutic response, nephrogenic DI was highly suspected. DI was resolved after 24 days. This case report describes the concomitant presence of RTA and DI in a dog after general anaesthesia.

Insights into the physical and chemical properties of struvite crystal surfaces in terms of the effectiveness of bacterial adhesion

In this paper, we present the results of research on the physicochemical properties of two selected faces of the struvite crystal, which is the main component of infectious urinary stones. Two main faces, (001) and ([Formula: see text]), ending the c-axis, were selected for the study. These faces are not related by symmetry relations, which means, among other things, that they should have a different atomic structure, which was confirmed experimentally. In addition, the studies show that the tested surfaces have hydrophilic properties, however, the ([Formula: see text]) face is more hydrophilic compared to the (001) face. The physicochemical properties of the crystal as a whole, as well as the physicochemical properties of these faces influence the magnitude of adhesion. The adhesive force in both water and artificial urine is greater for face ([Formula: see text]) compared to face (001). The assessment of the adhesion of Proteus mirabilis bacteria in artificial urine also shows that the adhesion is greater for face ([Formula: see text]) than for face (001). The adhesion of bacteria to the examined faces of the struvite crystal, and in particular the increased adhesion of bacteria to the face ([Formula: see text]), may be the first stage of biofilm formation, which may result in a high rate of recurrence of infectious urinary stones after treatment.

The role of microbiome: a novel insight into urolithiasis

Urolithiasis, referred to as the formation of stones in the urinary tract, is a common disease with growing prevalence and high recurrence rate worldwide. Although researchers have endeavoured to explore the mechanism of urinary stone formation for novel effective therapeutic and preventative measures, the exact aetiology and pathogenesis remain unclear. Propelled by sequencing technologies and culturomics, great advances have been made in understanding the pivotal contribution of the human microbiome to urolithiasis. Indeed, there are diverse and abundant microbes interacting with the host in the urinary tract, overturning the dogma that urinary system, and urine are sterile. The urinary microbiome of stone formers was clearly distinct from healthy individuals. Besides, dysbiosis of the intestinal microbiome appears to be involved in stone formation through the gut-kidney axis. Thus, the human microbiome has potential significant implications for the aetiology of urolithiasis, providing a novel insight into diagnostic, therapeutic, and prognostic strategies. Herein, we review and summarize the landmark microbiome studies in urolithiasis and identify therapeutic implications, challenges, and future perspectives in this rapidly evolving field. To conclude, a new front has opened with the evidence for a microbial role in stone formation, offering potential applications in the prevention, and treatment of urolithiasis.

Consumption of soft drinks rich in phosphoric acid versus struvite crystallization from artificial urine

In recent years, there has been a continuous increase in the incidence of urolithiasis, especially in highly developed countries. Therefore, the question arises which factors specific to these countries may be responsible for the increase in the incidence of this disease. In this article, we try to assess the effect of phosphoric acid, a component of various carbonated drinks, including Coca-Cola, on the nucleation and growth of struvite crystals, which are the main component of infectious urinary stones. The research was carried out in the environment of artificial urine with and without the presence of Proteus mirabilis bacteria. In the latter case, the activity of bacterial urease was simulated by adding an aqueous ammonia solution. The obtained results indicate that phosphoric acid present in artificial urine causes the nucleation of struvite to shift towards a lower pH, which means that struvite nucleates earlier in artificial urine compared to the control test. The amount of struvite formed is the greater the higher the concentration of phosphoric acid. At the same time, as the concentration of phosphoric acid increases, the growing struvite crystals are larger, which is disadvantageous because they are more difficult to remove from the urinary tract along with the urine. For the highest levels of phosphoric acid tested, large dendrites are formed, which are particularly undesirable as they can damage the epithelium of the urinary tract. The effect of phosphoric acid on the nucleation and growth of struvite is explained in base of chemical speciation analysis. This analysis indicates that the MgHCit and MgCit^- complexes have the main influence on the nucleation and growth of struvite in artificial urine in the presence of phosphoric acid. It should be keep in mind that all these effects of phosphoric acid are possible when the urinary tract is infected with urease-positive bacteria. In the absence of infection, phosphoric acid will not cause struvite to crystallize.

Concentrating stabilized urine with reverse osmosis: How does stabilization method and pre-treatment affect nutrient recovery, flux, and scaling?

Human urine can be used as a fertilizer, however, due to the high water content (97%), concentration is required to make transportation economically feasible. Reverse osmosis (RO) has been identified as an energy efficient concentration method. Furthermore, to maximize nitrogen recovery from source-separated urine it should be stabilized with an acid or base to prevent urea hydrolysis. However, the method of stabilization will have an impact on the downstream RO process. Calcium hydroxide is often used as a base stabilization method for human urine but would require pre-treatment to remove excess calcium and subsequent membrane scaling. Three pre-treatment methods such as air bubbling, NaHCO3 addition, and NH4HCO3 addition, were investigated in this study. Each method successfully reduced the scaling potential and air bubbling was determined to be the most effective method as it resulted in the highest nutrient recovery during concentration and did not require the addition of any chemicals. Base stabilization with air bubbling pre-treatment was then compared to urine stabilized with citric acid. Acid stabilized urine had a higher nitrogen recovery (7.6% higher). However, solids formed in the real acidified urine and during concentration a brown organic compound formed on the membrane surface. The crystals were identified as uric acid dihydrate and the brown organic fouling resulted in a significant decrease in permeate flux as compared to the base stabilized urine with air bubbling pre-treatment. At a 60% water recovery, 85.5% of the urea and 99.2% of the potassium was recovered in the brine stream and more than 99.9% of the phosphorus was recovered as a separate solid calcium phosphate fertilizer. Whilst nutrient recovery was higher with acid stabilization, the membrane fouling that occurred with this stabilization method meant that base stabilization with air bubbling pre-treatment was the preferred treatment option. It is recommended that acid stabilized urine be concentrated using evaporation processes instead.

First experimental evidence of the piezoelectric nature of struvite

In this paper, we present the first experimental evidence of the piezoelectric nature of struvite (MgNH₄PO₄·6H₂O). Using a single diffusion gel growth technique, we have grown struvite crystals in the form of plane parallel plates. For struvite crystals of this shape, we measured the piezoelectric coefficients d₃₃ and d₃₂. We have found that at room temperature the value of piezoelectric coefficient d₃₃ is 3.5 pm/V, while that of d₃₂ is 4.7 pm/V. These values are comparable with the values for other minerals. Struvite shows stable piezoelectric properties up to the temperature slightly above 350 K, for the heating rate of 0.4 K/min. For this heating rate, and above this temperature, the thermal decomposition of struvite begins, which, consequently, leads to its transformation into dittmarite with the same non-centrosymmetric symmetry as in case of struvite. The struvite-dittmarite transformation temperature is dependent on the heating rate. The higher the heating rate, the higher the temperature of this transformation. We have also shown that dittmarite, like struvite exhibits piezoelectric properties.

Structural and Optical Properties of Struvite. Elucidating Structure of Infrared Spectrum in High Frequency Range

Study of structure and optical properties of magnesium ammonium phosphate hexahydrate crystal known as struvite is presented. Experimentally determined infrared (IR) and ultraviolet-visible (UV-vis) spectra are compared with the theoretical predictions of density functional methods. Examination of the interatomic bond lengths, Mulliken atomic charges, and binding energies of water in the magnesium hexahydrate cation, together with the analysis of the hydrogen bond pattern have allowed us to explain a special feature of the IR spectrum of struvite, a blueshift of the band corresponding to the O-H stretching mode. This mode has been assigned to a "dangling" hydroxyl group in one of the water molecules in magnesium hexahydrate. Using experimentally obtained UV-vis spectrum and performing Tauc plots analysis, optical bandgap of struvite has been narrowed to a range from 5.92 to 6.06 eV.

Potentially Probiotic Lactobacillus Strains Derived from Food Intensify Crystallization Caused by Proteus mirabilis in Urine

Proteus mirabilis is a common cause of infectious urolithiasis. The first stage in the formation of urinary stones is the crystallization of mineral salts in the urine induced by urease activity of this microorganism. Lactobacillus spp. are an important component of the human microbiota and in large quantities occur in foods. Regardless of their origin, those with probiotic properties are proposed as an alternative to antibiotic therapy in the treatment of urinary tract infections. The aim of the study was to check the effect of selected Lactobacillus plantarum and Lactobacillus brevis strains on crystallization caused by P. mirabilis in an in vitro experiment. It has been confirmed that selected Lactobacillus strains have antibacterial properties and colonize the urinary tract epithelium. During 24-h incubation of bacterial cultures, containing P. mirabilis and individual Lactobacillus strains, in synthetic urine, bacterial viability (CFU/mL), pH, and crystallization were determined. Crystallization was assessed quantitatively and qualitatively using AAS and XRD techniques as well as phase-contrast microscopy. It has been shown that in the presence of selected Lactobacillus strains, the culture pH increases faster, especially after 8 h of incubation, compared with the pure P. mirabilis culture. An increase in pH reduces the viability of P. mirabilis; however, in the presence of some lactobacilli, the uropathogen grows more intensively. The presence of Lactobacillus also affected crystallization by increasing its intensity, and the resulting crystals were larger in size. Tested L. plantarum and L. brevis strains could therefore accelerate the formation of urinary stones and development of infection.

Time-Resolved Dynamics of Struvite Crystallization: Insights from the Macroscopic to Molecular Scale

The crystallization of magnesium ammonium phosphate hexahydrate (struvite) often occurs under conditions of fluid flow, yet the dynamics of struvite growth under these relevant environments has not been previously reported. In this study, we use a microfluidic device to evaluate the anisotropic growth of struvite crystals at variable flow rates and solution supersaturation. We show that bulk crystallization under quiescent conditions yields irreproducible data owing to the propensity of struvite to adopt defects in its crystal lattice, as well as fluctuations in pH that markedly impact crystal growth rates. Studies in microfluidic channels allow for time-resolved analysis of seeded growth along all three principle crystallographic directions and under highly controlled environments. After having first identified flow rates that differentiate diffusion and reaction limited growth regimes, we operated solely in the latter regime to extract the kinetic rates of struvite growth along the [100], [010], and [001] directions. In situ atomic force microscopy was used to obtain molecular level details of surface growth mechanisms. Our findings reveal a classical pathway of crystallization by monomer addition with the expected transition from growth by screw dislocations at low supersaturation to that of two-dimensional layer generation and spreading at high supersaturation. Collectively, these studies present a platform for assessing struvite crystallization under flow conditions and demonstrate how this approach is superior to measurements under quiescent conditions.

Aggregation of poorly crystalline and amorphous components of infectious urinary stones is mediated by bacterial lipopolysaccharide

Poorly crystalline and amorphous precipitate (PCaAP) is one of the components of the so-called infectious urinary stones, which are the result of the activity of urease-producing microorganisms, mainly from the Proteus species, in particular Proteus mirabilis. The main component of this kind of stones is crystalline struvite (MgNH4PO4∙6H2O). Bacteria can build into the structure of the urinary stone and, in this way, they are one of the components of the urinary stone. From these three components - PCaAP, struvite and Proteus mirabilis - PCaAP exhibits the greatest ability to aggregate. The present study focuses on the aggregation of PCaAP. In particular, an influence of lipopolysaccharide (LPS) isolated from Proteus mirabilis on aggregation of PCaAP is presented. An aggregation of PCaAP is characterized by cross-sectional area of aggregates and zeta potential. The results demonstrate that, in artificial urine, the influence of freely suspended LPS on aggregation of PCaAP depends on the concentrations of LPS. Small concentrations of freely suspended LPS enhance the aggregation of PCaAP compared to the control test. For high concentrations of freely suspended LPS the formation of aggregates of PCaAP is inhibited. LPS, which is not freely suspended, but covers polystyrene latex beads, has no such properties. The investigations provide evidence for the importance of biological regulation in the PCaAP aggregation process.

Potential Role of Extracellular ATP Released by Bacteria in Bladder Infection and Contractility

The ability of uropathogenic bacteria to release excitatory compounds, such as ATP, may act as a virulence factor to stimulate signaling pathways that could have profound effects on the urothelium, perhaps extending to the vagina. This may be countered by the ability of certain commensal urinary microbiota constituents, such as lactobacilli. Further understanding of these interactions is important for the treatment and prevention of UUI and OAB. The clinical implications may require a more targeted approach to enhance the commensal bacteria and reduce ATP release by pathogens.

Urgency urinary incontinence (UUI) and overactive bladder (OAB) can both potentially be influenced by commensal and urinary tract infection-associated bacteria. The sensing of bladder filling involves interplay between various components of the nervous system, eventually resulting in contraction of the detrusor muscle during micturition. This study models host responses to various urogenital bacteria, first by using urothelial bladder cell lines and then with myofibroblast contraction assays. To measure responses, we examined Ca²⁺ influx, gene expression, and alpha smooth muscle actin deposition assays. Organisms such as Escherichia coli and Gardnerella vaginalis were found to strongly induce Ca²⁺ influx and contraction, whereas Lactobacillus crispatus and L. gasseri did not induce this response. Additionally, supernatants from lactobacilli impeded Ca²⁺ influx and contraction induced by uropathogens. Upon further investigation of factors associated with purinergic signaling pathways, the Ca²⁺ influx and contraction of cells correlated with the amount of extracellular ATP produced by E. coli. Certain lactobacilli appear to mitigate this response by utilizing extracellular ATP or producing inhibitory compounds that may act as a receptor agonist or Ca²⁺ channel blocker. These findings suggest that members of the urinary microbiota may be influencing UUI or OAB.

IMPORTANCE The ability of uropathogenic bacteria to release excitatory compounds, such as ATP, may act as a virulence factor to stimulate signaling pathways that could have profound effects on the urothelium, perhaps extending to the vagina. This may be countered by the ability of certain commensal urinary microbiota constituents, such as lactobacilli. Further understanding of these interactions is important for the treatment and prevention of UUI and OAB. The clinical implications may require a more targeted approach to enhance the commensal bacteria and reduce ATP release by pathogens.

Encrustations on ureteral stents from patients without urinary tract infection reveal distinct urotypes and a low bacterial load

BACKGROUND

Current knowledge of the urinary tract microbiome is limited to urine analysis and analysis of biofilms formed on Foley catheters. Bacterial biofilms on ureteral stents have rarely been investigated, and no cultivation-independent data are available on the microbiome of the encrustations on the stents.

RESULTS

The typical encrustations of organic and inorganic urine-derived material, including microbial biofilms formed during 3-6 weeks on ureteral stents in patients treated for kidney and ureteral stones, and without reported urinary tract infection at the time of stent insertion, were analysed. Next-generation sequencing of the 16S rRNA gene V3-V4 region revealed presence of different urotypes, distinct bacterial communities. Analysis of bacterial load was performed by combining quantification of 16S rRNA gene copy numbers by qPCR with microscopy and cultivation-dependent analysis methods, which revealed that ureteral stent biofilms mostly contain low numbers of bacteria. Fluorescence microscopy indicates the presence of extracellular DNA. Bacteria identified in biofilms by microscopy had mostly morphogenic similarities to gram-positive bacteria, in few cases to Lactobacillus and Corynebacterium, while sequencing showed many additional bacterial genera. Weddellite crystals were absent in biofilms of patients with Enterobacterales and Corynebacterium-dominated microbiomes.

CONCLUSIONS

This study provides novel insights into the bacterial burden in ureteral stent encrustations and the urinary tract microbiome. Short-term (3-6 weeks) ureteral stenting is associated with a low load of viable and visible bacteria in ureteral stent encrustations, which may be different from long-term stenting. Patients could be classified according to different urotypes, some of which were dominated by potentially pathogenic species. Facultative pathogens however appear to be a common feature in patients without clinically manifested urinary tract infection.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02845726 . Registered on 30 June 2016-retrospectively registered.

Struvite Grown in Gel, Its Crystal Structure at 90 K and Thermoanalytical Study

In this article, we report the crystallization of struvite in sodium metasilicate gel by single diffusion gel growth technique. The obtained crystals have a very rich morphology displaying 18 faces. In this study, the habit and morphology of the obtained struvite crystals are analyzed. The crystals were examined and identified as pure struvite by single X-ray diffraction (XRD). The orthorhombic polar noncentrosymmetric space group Pmn21 was identified. The structure of the crystal was determined at a temperature of 90 K. Our research indicates a lack of polymorphism, resulting from the temperature lowering to 90 K, which has not been previously reported. The determined unit cell parameters are as follows a = 6.9650(2) Å, b = 6.1165(2) Å, c = 11.2056(3) Å. The structure of struvite is presented here with a residual factor R1 = 1.2% at 0.80 Å resolution. We also present thermoanalytical study of struvite using thermal analysis techniques such as thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA).

Influence of various uropathogens on crystallization of urine mineral components caused by Proteus mirabilis

Infectious urolithiasis is a consequence of long-standing urinary tract infections with urease-positive bacteria, especially Proteus spp. However, because of the often mixed nature of urinary tract infections, in the case of urinary stones formation, several species of bacteria may be involved in the process. The purpose of the study was to determine the impact of the bacterial species: Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa and Staphylococcus aureus on the crystallization caused by Proteus mirabilis. The studies were conducted in synthetic urine with the addition of P. mirabilis and a representative of another species. During the experiments the viability of bacteria, pH, presence and morphology of crystals, and the intensity of crystallization were assessed. Crystallization of calcium and magnesium phosphates occurred in all investigated configurations. However, there were differences observed in the course and intensity of crystallization between the mixed culture and the P. mirabilis culture. Although most intense crystallization took place in the pure culture of P. mirabilis it was also demonstrated that the presence of other uropathogens increased the survival of P. mirabilis. This synergistic effect could be responsible for the persistence and recurrence of urolithiasis in the urinary tract.

Formation of struvite urinary stones and approaches towards the inhibition-A review

BACKGROUND

Struvite is one of the most common urinary/kidney stones, composed of magnesium ammonium phosphate (MgNHPO₄·H₂O). They are also termed as infection stones as these are associated with urinary tract infections. Numerous studies have been carried out to examine the growth and inhibition of struvite stones.

OBJECTIVE

This review summarizes various reports on the factors responsible for inducing struvite stones in the kidney and gives a detailed account of studies on inhibition of growth of struvite crystals.

RESULTS

The presence of urea-splitting bacteria such as Proteus mirabilis and alkaline pH plays a crucial role in struvite formation. In vitro inhibition of struvite stones by various chemical agents were examined mainly in artificial urine whereas inhibition by herbal extracts was studied in vitro by gel diffusion technique. Herbal extracts of curcumin, Boerhaavia diffusa Linn, Rotula aquatica and many other plants, as well as some chemicals like pyrophosphate, acetohydroxamic acid, disodium EDTA and trisodium citrate, were reported to successfully inhibit struvite formation.

CONCLUSION

The present review recapitulates various factors affecting the growth of struvite urinary stones and the inhibitory role of certain chemicals and herbal extracts. Most of the tested plants are edible hence can be easily consumed without any adverse effects whereas the side effects of chemicals are unknown due to lack of toxicity studies. Thus, the use of herbal extracts might serve as an alternate and safe therapy for prevention of struvite stones.

Temperature-dependent μ-Raman investigation of struvite crystals

The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by μ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353 K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298-423 K reveal a phase transition in struvite at about 368 K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures.

Bacterial signaling ecology and potential applications during aquatic biofilm construction

In their natural environment, bacteria and other microorganisms typically grow as surface-adherent biofilm communities. Cell signal processes, including quorum signaling, are now recognized as being intimately involved in the development and function of biofilms. In contrast to their planktonic (unattached) counterparts, bacteria within biofilms are notoriously resistant to many traditional antimicrobial agents and so represent a major challenge in industry and medicine. Although biofilms impact many human activities, they actually represent an ancient mode of bacterial growth as shown in the fossil record. Consequently, many aquatic organisms have evolved strategies involving signal manipulation to control or co-exist with biofilms. Here, we review the chemical ecology of biofilms and propose mechanisms whereby signal manipulation can be used to promote or control biofilms.

Significance of the D-serine-deaminase and D-serine metabolism of Staphylococcus saprophyticus for virulence

Staphylococcus saprophyticus is the only species of Staphylococcus that is typically uropathogenic and possesses a gene coding for a D-serine-deaminase (DsdA). As D-serine is prevalent in urine and toxic or bacteriostatic to many bacteria, it is not surprising that the D-serine-deaminase gene is found in the genome of uropathogens. It has been suggested that D-serine-deaminase or the ability to respond to or to metabolize D-serine is important for virulence. For uropathogenic Escherichia coli (UPEC), a high intracellular D-serine concentration affects expression of virulence factors. S. saprophyticus is able to grow in the presence of high D-serine concentrations; however, its D-serine metabolism has not been described. The activity of the D-serine-deaminase was verified by analyzing the formation of pyruvate from D-serine in different strains with and without D-serine-deaminase. Cocultivation experiments were performed to show that D-serine-deaminase confers a growth advantage to S. saprophyticus in the presence of D-serine. Furthermore, in vivo coinfection experiments showed a disadvantage for the ΔdsdA mutant during urinary tract infection. Expression analysis of known virulence factors by reverse transcription-quantitative PCR (RT-qPCR) showed that the surface-associated lipase Ssp is upregulated in the presence of D-serine. In addition, we show that S. saprophyticus is able to use D-serine as the sole carbon source, but interestingly, D-serine had a negative effect on growth when glucose was also present. Taken together, D-serine metabolism is associated with virulence in S. saprophyticus, as at least one known virulence factor is upregulated in the presence of D-serine and a ΔdsdA mutant was attenuated in virulence murine model of urinary tract infection.

From rainfall to throughfall in a maritime vineyard

This study deals with the characteristics of throughfall produced by vine (Vitis vinifera L.) in one of the most common pedoclimatic conditions for grape production: a soil derived from marine sediments under a temperate Mediterranean climate, and located rather close to the seacoast. To distinguish the contribution of the plant from that of the atmospheric deposition, the throughfall was collected for more than one year under real and artificial (plastic) vines; for the same period, also the bulk precipitation was collected. The solution collected were analysed for pH, electrical conductivity, and concentration of cations and anions. For each event, the ionic fluxes of bulk precipitation and throughfall were calculated. Results indicated that the chemical composition of the bulk precipitation was strongly influenced by the proximity of the seashore and, to a lesser extent, by local anthropic activities and windblown material coming from distant areas. The chemical composition of the throughfall was affected by the same factors of bulk precipitation, but also by solubilisation of dry deposition trapped by the canopies, agronomic practices, plant, and living-on-the-leaves microorganisms. The comparison of the characteristics of the throughfall of the real with the artificial vines revealed that the vines are a source of Mg and K. During winter season, the reduction of Ca, NH(4) and PO(4) from bulk precipitation to throughfall was ascribed to the formation of biogenic minerals on the plant surface. The presence of these minerals was proved by X-ray diffraction on the powders collected during the winter season on the surface of cordons and fruiting canes. We conclude that an approach to the estimation of the nutritional potentiality of the soil that includes the contribution of the throughfall is functional to the management of the agro-ecosystem.

Urease activity represents an alternative pathway for Mycobacterium tuberculosis nitrogen metabolism

Urease represents a critical virulence factor for some bacterial species through its alkalizing effect, which helps neutralize the acidic microenvironment of the pathogen. In addition, urease serves as a nitrogen source provider for bacterial growth. Pathogenic mycobacteria express a functional urease, but its role during infection has yet to be characterized. In this study, we constructed a urease-deficient Mycobacterium tuberculosis strain and confirmed the alkalizing effect of the urease activity within the mycobacterium-containing vacuole in resting macrophages but not in the more acidic phagolysosomal compartment of activated macrophages. However, the urease-mediated alkalizing effect did not confer any growth advantage on M. tuberculosis in macrophages, as evidenced by comparable growth profiles for the mutant, wild-type (WT), and complemented strains. In contrast, the urease-deficient mutant exhibited impaired in vitro growth compared to the WT and complemented strains when urea was the sole source of nitrogen. Substantial amounts of ammonia were produced by the WT and complemented strains, but not with the urease-deficient mutant, which represents the actual nitrogen source for mycobacterial growth. However, the urease-deficient mutant displayed parental colonization profiles in the lungs, spleen, and liver in mice. Together, our data demonstrate a role for the urease activity in M. tuberculosis nitrogen metabolism that could be crucial for the pathogen's survival in nutrient-limited microenvironments where urea is the sole nitrogen source. Our work supports the notion that M. tuberculosis virulence correlates with its unique metabolic versatility and ability to utilize virtually any carbon and nitrogen sources available in its environment.

Effect of Curcumin Against Proteus mirabilis During Crystallization of Struvite from Artificial Urine

We investigated the activity of curcumin against Proteus mirabilis and the struvite crystallization in relation to urinary stones formation. In order to evaluate an activity of curcumin we performed an in vitro experiment of struvite growth from artificial urine. The crystallization process was induced by Proteus mirabilis to mimic the real urinary tract infection, which usually leads to urinary stone formation. The results demonstrate that curcumin exhibits the effect against Proteus mirabilis inhibiting the activity of urease—an enzyme produced by these microorganisms. Addition of curcumin increases the induction time and decreases the efficiency of growth of struvite compared with the absence of curcumin. Interestingly, the addition of curcumin does not affect the crystal morphology and habit. In conclusion, curcumin has demonstrated its significant potential to be further investigated for its use in the case of struvite crystallization induced for the growth by Proteus mirabilis in relation to urinary stone formation.

Interplay of metal ions and urease

Urease, the first enzyme to be crystallized, contains a dinuclear nickel metallocenter that catalyzes the decomposition of urea to produce ammonia, a reaction of great agricultural and medical importance. Several mechanisms of urease catalysis have been proposed on the basis of enzyme crystal structures, model complexes, and computational efforts, but the precise steps in catalysis and the requirement of nickel versus other metals remain unclear. Purified bacterial urease is partially activated via incubation with carbon dioxide plus nickel ions; however, in vitro activation also has been achieved with manganese and cobalt. In vivo activation of most ureases requires accessory proteins that function as nickel metallochaperones and GTP-dependent molecular chaperones or play other roles in the maturation process. In addition, some microorganisms control their levels of urease by metal ion-dependent regulatory mechanisms.

[Urinary tract infections and Urolithiasis]

The classic "infection stone" struvite is formed as a result of metabolic activity of urease-positive bacteria from alkaline urine with pH-values above 7.5. Due to improved infection diagnostics and antibiotic therapy, the occurrence of infection-related urinary stones in the western industrialized world decreases, despite the generally increasing prevalence rates of urolithiasis in these societies. Struvite is often associated with other mineral phases. These accessory mineral phases could indicate other, non-infection-related causes of urinary stone formation. Thus, mineral analysis is always recommended. Struvite stones as well as struvite encrustations on urinary tract implants are characterized by rapid growth. The rapid growth-related embedding of urease-positive bacteria in the crystalline material makes the urinary stone a persistent source of recurrent urinary tract infections. According to the German Society of Urology guidelines on urolithiasis, a patient with the diagnosis "infection stone" should be assigned to the "high-risk" patient group. Complete stone and debris removal, as well as a special metaphylaxis strategy are required to initiate successful stone therapy.

A previously uncharacterized gene, yjfO (bsmA), influences Escherichia coli biofilm formation and stress response

Bacteria growing as surface-adherent biofilms are better able to withstand chemical and physical stresses than their unattached, planktonic counterparts. Using transcriptional profiling and quantitative PCR, we observed a previously uncharacterized gene, yjfO to be upregulated during Escherichia coli MG1655 biofilm growth in a chemostat on serine-limited defined medium. A yjfO mutant, developed through targeted-insertion mutagenesis, and a yjfO-complemented strain, were obtained for further characterization. While bacterial surface colonization levels (c.f.u. cm(-2)) were similar in all three strains, the mutant strain exhibited reduced microcolony formation when observed in flow cells, and greatly enhanced flagellar motility on soft (0.3 %) agar. Complementation of yjfO restored microcolony formation and flagellar motility to wild-type levels. Cell surface hydrophobicity and twitching motility were unaffected by the presence or absence of yjfO. In contrast to the parent strain, biofilms from the mutant strain were less able to resist acid and peroxide stresses. yjfO had no significant effect on E. coli biofilm susceptibility to alkali or heat stress. Planktonic cultures from all three strains showed similar responses to these stresses. Regardless of the presence of yjfO, planktonic E. coli withstood alkali stress better than biofilm populations. Complementation of yjfO restored viability following exposure to peroxide stress, but did not restore acid resistance. Based on its influence on biofilm maturation and stress response, and effects on motility, we propose renaming the uncharacterized gene, yjfO, as bsmA (biofilm stress and motility).

Biofilms in nephrology

BACKGROUND

Biofilms are bacterial communities ubiquitous to moist environments. Biofilm formation is a factor in the development and persistence of infectious diseases. In clinical nephrology, biofilms influence the development of kidney stones and affect dialysis systems, including peritoneal and central venous catheters. Biofilms also play critical roles in persistent and resistant renal and urinary tract infections.

OBJECTIVE

To describe the physiology of biofilms and potential effects of biofilms upon infectious diseases, focusing on the role of biofilms in kidney stones, indwelling catheters and dialysis equipment.

METHODS

A literature search with Medline to identify pertinent English language articles published up to early 2008 using the keywords biofilm, nephrology, renal, calculi and infection.

RESULTS/CONCLUSION

Biofilms are ubiquitous in clinical nephrology and play a role in the pathogenesis of resistant infections. Strategies for reducing the effects of biofilms in nephrology are described.

Giant bladder stone in a natural mummy of the early 19th century

We present a case of a giant bladder stone, 7.5 cm in diameter, found in the pelvis of a 19th-century natural mummy from Borgo Cerreto (central Italy). We used microchemical energy-dispersive x-ray spectroscopy analysis and x-ray diffraction to define the mineral composition of the stone and obtain information about its internal structure. Chemical analysis showed a mixed composition. The internal layers contained mostly ammonium acid urate, whereas the external layers were composed of magnesium ammonium phosphate (struvite). Our research suggests a metabolic origin for the calculosis, with superimposed infection.

Complicated catheter-associated urinary tract infections due to Escherichia coli and Proteus mirabilis

Catheter-associated urinary tract infections (CAUTIs) represent the most common type of nosocomial infection and are a major health concern due to the complications and frequent recurrence. These infections are often caused by Escherichia coli and Proteus mirabilis. Gram-negative bacterial species that cause CAUTIs express a number of virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, and nutrient acquisition as well as factors that cause damage to the host. These infections can be reduced by limiting catheter usage and ensuring that health care professionals correctly use closed-system Foley catheters. A number of novel approaches such as condom and suprapubic catheters, intermittent catheterization, new surfaces, catheters with antimicrobial agents, and probiotics have thus far met with limited success. While the diagnosis of symptomatic versus asymptomatic CAUTIs may be a contentious issue, it is generally agreed that once a catheterized patient is believed to have a symptomatic urinary tract infection, the catheter is removed if possible due to the high rate of relapse. Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.

Brucella suis urease encoded by ure1 but not ure2 is necessary for intestinal infection of BALB/c mice

BACKGROUND

In prokaryotes, the ureases are multi-subunit, nickel-containing enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. The Brucella genomes contain two urease operons designated as ure1 and ure2. We investigated the role of the two Brucella suis urease operons on the infection, intracellular persistence, growth, and resistance to low-pH killing.

RESULTS

The deduced amino acid sequence of urease-alpha subunits of operons-1 and -2 exhibited substantial identity with the structural ureases of alpha- and beta-proteobacteria, Gram-positive and Gram-negative bacteria, fungi, and higher plants. Four ure deficient strains were generated by deleting one or more of the genes encoding urease subunits of B. suis strain 1330 by allelic exchange: strain 1330Deltaure1K (generated by deleting ureD and ureA in ure1 operon), strain 1330Deltaure2K (ureB and ureC in ure2 operon), strain 1330Deltaure2C (ureA, ureB, and ureC in ure2 operon), and strain 1330Deltaure1KDeltaure2C (ureD and ureA in ure1 operon and ureA, ureB, and ureC in ure2 operon). When grown in urease test broth, strains 1330, 1330Deltaure2K and 1330Deltaure2C displayed maximal urease enzyme activity within 24 hours, whereas, strains 1330Deltaure1K and 1330Deltaure1KDeltaure2C exhibited zero urease activity even 96 h after inoculation. Strains 1330Deltaure1K and 1330Deltaure1KDeltaure2C exhibited slower growth rates in tryptic soy broth relative to the wild type strain 1330. When the BALB/c mice were infected intraperitoneally with the strains, six weeks after inoculation, the splenic recovery of the ure deficient strains did not differ from the wild type. In contrast, when the mice were inoculated by gavage, one week after inoculation, strain 1330Deltaure1KDeltaure2C was cleared from livers and spleens while the wild type strain 1330 was still present. All B. suis strains were killed when they were incubated in-vitro at pH 2.0. When the strains were incubated at pH 2.0 supplemented with 10 mM urea, strain 1330Deltaure1K was completely killed, strain 1330Deltaure2C was partially killed, but strains 1330 and 1330Deltaure2K were not killed.

CONCLUSION

These findings suggest that the ure1 operon is necessary for optimal growth in culture, urease activity, resistance against low-pH killing, and in vivo persistence of B. suis when inoculated by gavage. The ure2 operon apparently enhances the resistance to low-pH killing in-vitro.

The role of Klebsiella pneumoniae urease in intestinal colonization and resistance to gastrointestinal stress

The first step in nosocomial infections due to Klebsiella pneumoniae is colonization of the patient's gastrointestinal (GI) tract. In a previous work, signature-tagged mutagenesis was used in a murine model to identify 13 genes required for efficient colonization, two of which were involved in urea metabolism. The role of urease was further investigated by the construction and analysis of an isogenic urease-deficient mutant. The behavior of both the wild-type strain and the urease-deficient mutant was tested under hostile conditions, reproducing stresses encountered in the GI environment. The wild-type strain had an acid tolerance response (ATR) to inorganic acid, was resistant to organic acids (38.5% survival) and was able to survive concentrations of bile encountered in vivo. The absence of urease did not affect the resistance of K. pneumoniae to acid and bile stresses, but the enhanced adhesion response to Int-407 cells after exposure to bile observed with the wild-type strain was no longer detected with the urease mutant. When tested in the murine intestinal colonization model, both strains were mainly recovered in the large intestine parts, and the mutant was impaired in its colonization capacities, but only when tested in competition with the wild-type strain. These findings emphasize the prominent role played by metabolic function in the colonization process of such a complex ecosystem as the host GI tract.

Cellular and molecular gateways to urolithiasis: a new insight

Urolithiasis is a relevant clinical problem in everyday practice with a subsequent burden for the health system. Urolithiasis is classically explained as the derangement in the process of biomineralization involving the equilibrium between promoters and inhibitors of crystallization: a deficit of one or several inhibitors or an excess of one or several promoters plays a pivotal role in the stone formation. The revolutionary introduction of the molecular biology in medicine has given a new insight in urolithiasis too. Genetic factors have also been postulated to play an important role. A review of the current knowledge on urolithiasis based upon a molecular and genetic approach is reported.