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.

Multiple drug resistance bacterial isolates and associated factors among urinary stone patients at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

BACKGROUND: The urinary stone and urinary tract infection (UTI) are invariably associated and are frequent causes of morbidity. Date on burden of UTI among urinary stone patients is lacking in Ethiopia. This study was aimed to assess bacterial profile, antimicrobial susceptibility and associated factors among urinary stone patients at the University of Gondar Comprehensive Specialized Hospital. METHODS: An institution based cross sectional study was conducted. Basic sociodemographic data were collected using a structured questionnaire. Bacterial identification of uropathogens and drug susceptibility testing were done following standard microbiological techniques. The data were entered and analyzed using SPSS version-23. Bivariate and multivariate logistic regressions were used to identify possible associated risk factors. Results with P value < 0.05 was considered statistically significant. RESULT: A total of 300 urinary stone patients were enrolled. Of these, 153 (51%) were male and 261(87%) were urban residents. The overall prevalence of urinary tract infection was 49 (16.3%) (95% CI 12-21%). A high level of resistance was observed to ampicillin, penicillin and trimethoprim-sulfamethoxazole while majority of isolates were most sensitive to nitrofurantoin and ciprofloxacin. Multi-drug resistant isolates were 16/49 (32.7%), 75% of them being Enterobacteriaceae isolates. More than one-third 9/26 (34.6%) of Gram-negative isolates were Extended Spectrum Beta-Lactamase (ESBL) producing E. coli and K. pneumoniae. Being female, history of urinary tract infection and history of drug use were the independent risk factors. CONCLUSION: Most of the bacterial isolates from urinary stone patients were resistant to ampicillin, penicillin and trimethoprim-sulfamethoxazole. E. coli and K. pneumoniae were the most common extended spectrum beta-lactamase producing isolates. Sex, history of urinary tract infection and previous drug use were found to be risk factors. Routine diagnosis of urinary stone patients for urinary tract infection should be promoted and further researches are encouraged.

Microbiological Features and Clinical Factors Associated with Empirical Antibiotic Resistance in Febrile Patients with Upper Urinary Tract Calculi.

BACKGROUND: To investigate the clinical and microbiological features of febrile patients with upper urinary tract calculi and factors that affect empirical antibiotic resistance. METHODS: A retrospective analysis was performed on 203 febrile patients hospitalized between January 2011 and December 2016 with antibiotic treatment for urinary tract infections and upper urinary tract calculi at three institutions. We collected and analyzed data, including patients' age, sex, body mass index, underlying diseases, stone-related factors, and the results of urine and blood culture examinations and antibiotic sensitivity tests. RESULTS: The male-to-female ratio was 1:2.3. Bacteria were identified in 152 of the 203 patients (74.9%). The most commonly cultured microorganisms included Escherichia coli (44.1%), followed by Enterococci spp. (11.8%), Proteus spp. (8.6%), Streptococcus agalactiae (6.6%), Klebsiella spp. (5.3%), Pseudomonas spp. (4.6%), coagulase-negative Staphylococcus (4.0%), Staphylococcus epidermidis (4.0%), Serratia spp. (2.6%), Enterobacter spp. (0.7%), Acinetobacter spp. (0.7%), and mixed infections (7.2%). Cultured bacterial species showed sex-specific differences. Multivariate analysis revealed that calculi's multiplicity was an independent predictive factor for quinolone resistance (P = 0.008). Recurrent infections were a significant predictor of cefotaxime resistance during multivariable analysis (P = 0.041). CONCLUSION: Based on the present study results, quinolone was not recommended as the empirical treatment in febrile patients with upper urinary tract calculi. Combination antibiotic therapy is recommended in cases of recurrent infections due to the possible occurrence of cefotaxime resistance.

Dysbiosis of urine microbiota in obstructive urinary retention patients revealed by next-generation sequencing.

BACKGROUND: Urinary retention (UR) is a common urinary system disease can be caused by urinary tract obstruction with numerous reasons, however, the role of urine microbes in these disorders is still poorly understood. The aim of this study was to identify the urine microbial features of two common types of obstructive UR, caused by urinary stones or urinary tract tumors, with comparison to healthy controls. METHODS: Urine samples were collected from a cohort of 32 individuals with stone UR, 25 subjects with tumor UR and 25 healthy controls. The urine microbiome of all samples was analyzed using high-throughput 16S rRNA (16S ribosomal RNA) gene sequencing. RESULTS: We observed dramatically increased urine microbial richness and diversity in both obstructive UR groups compared to healthy controls. Despite different origins of UR, bacteria such as Pseudomonas, Acinetobacter and Sphingomonas were enriched, while Lactobacillus, Streptococcus, Gardnerella, Prevotella and Atopobium were decreased in both UR groups in comparison with healthy controls, exhibited an approximate urine microbial community and functional characteristics of two types of obstructive UR. Furthermore, disease classifiers were constructed using specific enriched genera in UR, which can distinguish stone UR or tumor UR patients from healthy controls with an accuracy of 92.29% and 97.96%, respectively. CONCLUSION: We presented comprehensive microbial landscapes of two common types of obstructive urinary retention and demonstrated that urine microbial features of these patients are significantly different from that of healthy people. The urine microbial signatures would shed light on the pathogenesis of these types of urinary retention and might be used as potential classification tools in the future.

[Bacteriological correlation of urinary stones and preoperative urine culture: Is there a significant impact on postoperative infectious risk? (Moroccan experience)]. / Corrélation bactériologique entre les calculs urinaires et l'ECBU préopératoire : a-t-il un impact sur le risque infectieux postopératoire ? (expérience marocaine).

AIM: The objectives of this study were to evaluate the impact of preoperative urine culture and the infected nature of stones on the occurrence of postoperative urinary sepsis. MATERIAL AND METHODS: A prospective monocentric study included 29 patients operated on for urolithiasis between January and June 2018. RESULTS: Postoperative urinary sepsis was observed in 4 patients (14%). Urinary colonization rate on preoperative CBU exam was 27.6% (8 of 29) while the rate of colonized stones was 31% (9 of 29). The occurrence of urinary sepsis was observed in 37.5% (3 of 8) of patients with urinary colonization, compared to 44.4% of patients with colonized stones (4 of 9). By comparing the bacteriological results observed during sepsis, the germs isolated in postoperative urine were the same found in the culture of stones. The chemical nature of the colonized stones was mainly calcium oxalate (monohydrate, dihydrate) P=0.02. There was a statistically significant correlation between the preoperative urine culture, the bacteriological culture of stones and the postoperative urinary sepsis (P=0.05, P=0.005) respectively. CONCLUSION: Our study demonstrated a strong association between the bacteriological culture of stones and postoperative urinary sepsis superior to preoperative urine culture. It makes it possible to anticipate the occurrence of sepsis in patients requiring many endoscopic treatments. However, several multicentric prospective series may prove necessary to validate these results. LEVEL OF EVIDENCE: 3.

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.

Deacidification by FhlA-dependent hydrogenase is involved in urease activity and urinary stone formation in uropathogenic Proteus mirabilis.

Proteus mirabilis is an important uropathogen, featured with urinary stone formation. Formate hydrogenlyase (FHL), consisting of formate dehydrogenase H and hydrogenase for converting proton to hydrogen, has been implicated in virulence. In this study, we investigated the role of P. mirabilis FHL hydrogenase and the FHL activator, FhlA. fhlA and hyfG (encoding hydrogenase large subunit) displayed a defect in acid resistance. fhlA and hyfG mutants displayed a delay in medium deacidification compared to wild-type and ureC mutant failed to deacidify the medium. In addition, loss of fhlA or hyfG decreased urease activity in the pH range of 5-8. The reduction of urease activities in fhlA and hyfG mutants subsided gradually over the pH range and disappeared at pH 9. Furthermore, mutation of fhlA or hyfG resulted in a decrease in urinary stone formation in synthetic urine. These indicate fhlA- and hyf-mediated deacidification affected urease activity and stone formation. Finally, fhlA and hyfG mutants exhibited attenuated colonization in mice. Altogether, we found expression of fhlA and hyf confers medium deacidification via facilitating urease activity, thereby urinary stone formation and mouse colonization. The link of acid resistance to urease activity provides a potential strategy for counteracting urinary tract infections by P. mirabilis.

The Relationship between Urinary Stones and Gut Microbiomeby 16S Sequencing.

OBJECTIVE: To understand the relationship between urinary stones and the gut microbiome and to screen for microbial species that may be involved in stone formation. METHODS: Stool samples were collected from patients with urolithiasis and healthy patients between March and December 2017. The samples were analyzed by 16S sequencing to determine differences in the microbiome profiles between the two groups. The mouse model was established and was divided into two groups. Fecal samples were collected from the mice before gavage and three weeks postgavage for microbiome analysis. The microbial population of each group was analyzed to screen for microbial species that may affect the formation of urinary stones. Differences in the number of crystals in the renal tubules of the mice were examined by necropsy. RESULTS: The microbial composition was different between urolithiasis patients and healthy controls. The urolithiasis patients had significantly reduced microbial abundance; however, increased proportions of Bacteroidetes and Actinobacteria were detected compared to healthy controls. Furthermore, the abundance of Alistipesindistinctus and Odoribactersplanchnicus was significantly increased in the urolithiasis patients compared to the healthy controls. In addition, the incidence of urolithiasis was much higher in the experimental mouse group (stone solution + urolithiasis patient stool) than in the control mouse group. However, the microbial abundance before gavage was not significantly different from that seen three weeks postgavage. CONCLUSION: Theurolithiasis patients in this study had a different gut microbiome when compared with that of healthy individuals. The altered microbiome increased the rate of crystal formation in renal tubules and accelerated urinary stone formation in the mouse model of urolithiasis.

The microbiome of calcium-based urinary stones.

Historically, the role of bacteria in urinary stone disease (USD) has been limited to urease-producing bacteria associated with struvite stone formation. However, growing evidence has revealed bacteria associated with stones of non-struvite composition. These bacteria may be derived from either urine or from the stones themselves. Using 16S rRNA gene sequencing and an enhanced culture technique (EQUC), we identified the urine and stone microbiota of USD patients and then determined if bacteria were statistically enriched in the stones relative to the urine. From 52 patients, bladder urine and urinary stones were collected intraoperatively during ureteroscopy. Stone homogenate and urine specimens were subjected to 16S rRNA gene sequencing and EQUC. Standard Chi-squared tests were applied to determine if the relative abundance of any bacterial taxon was significantly enriched in urinary stones compared to urine. Stones were primarily calcium-based. 29/52 (55.8%) stones had bacteria detected by 16S rRNA gene sequencing. Of these, dominant bacterial taxa were enriched from 12 stones. Bacterial taxa isolated by EQUC include members of the genera Staphylococcus, Enterobacter, Escherichia, Corynebacterium, and Lactobacillus. Dominant bacterial genera were enriched compared to paired bladder urine. Differences between the stone and urine microbiota may indicate that certain bacteria contribute to USD pathophysiology. Further investigation is warranted.

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.

Inhibition of urinary stone disease by a multi-species bacterial network ensures healthy oxalate homeostasis.

The incidence of urinary stone disease is rapidly increasing, with oxalate being a primary constituent of approximately 80% of all kidney stones. Despite the high dietary exposure to oxalate by many individuals and its potential nephrotoxicity, mammals do not produce enzymes to metabolize this compound, instead relying in part on bacteria within the gut to reduce oxalate absorption and urinary excretion. While considerable research has focused on isolated species of oxalate-degrading bacteria, particularly those with an absolute requirement for oxalate, recent studies have pointed to broader roles for microbiota both in oxalate metabolism and inhibition of urinary stone disease. Here we examined gut microbiota from patients with and live-in individuals without urinary stone disease to determine if healthy individuals harbored a more extensive microbial network associated with oxalate metabolism. We found a gender-specific association between the gut microbiota composition and urinary stone disease. Bacteria enriched in healthy individuals largely overlapped with those that exhibited a significant, positive correlation with Oxalobacter formigenes, a species presumed to be at the center of an oxalate-metabolizing microbial network. Furthermore, differential abundance analyses identified multiple taxa known to also be stimulated by oxalate in rodent models. Interestingly, the presence of these taxa distinguished patients from healthy individuals better than either the relative abundance or colonization of O. formigenes. Thus, our work shows that bacteria stimulated by the presence of oxalate in rodents may, in addition to obligate oxalate users, play a role in the inhibition of urinary stone disease in man.

Understanding the Link Between Gut Microbiome and Urinary Stone Disease.

PURPOSE OF REVIEW: With recent advances in sequencing technologies and increasing research into the gut microbiome (GMB), studies have revealed associations between the GMB and urinary stone disease (USD). We sought to determine whether the evidence pointed towards a few specific gut bacteria or the broader GMB network is seemingly responsible for this relationship. RECENT FINDINGS: Initially, Oxalobacter formigenes (OF) was pursued as the main link between GMB and USD given its ability to degrade oxalate in the gut. However, the latest studies consistently suggest that the entire GMB is much more likely to be involved in handling oxalate absorption and other risk factors for urinary stone formation, rather than just a few microbiota. The GMB has complex networks that are likely involved in the pathophysiology of USD, although the causal mechanisms remain unclear. With increasing interest and research, potential modalities that act on the GMB may help to prevent incidence of USD.

Comparison between non-septic and septic cases in stone-related obstructive acute pyelonephritis and risk factors for septic shock: A multi-center retrospective study.

PURPOSE: This study assessed risk factors for septic shock in patients with obstructive acute pyelonephritis (APN) associated with upper urinary tract calculi in a multi-center retrospective study. METHODS: We studied 143 patients admitted to 4 hospitals in Japan with obstructive APN associated with upper urinary tract calculi. Data on gender, age, hypertension, diabetes, neurological disease or malignant disease, laboratory data (white blood cell (WBC) and C-reactive protein (CRP)), drainage, and bacterial strains including Escherichia coli in the non-septic and septic groups were collected. Risk factors for septic shock were analyzed by univariate and multivariate statistical analyses. RESULTS: There were a total of 107 non-septic cases (74.8%) and 36 septic cases (25.2%). The commonest strains of urinary tract infection-causative bacteria were E. coli in the non-septic group (23 cases, 21.5%) and septic group (13 cases, 36.1%) (p > 0.05). Emergency drainage was administered in 74.8% of the non-septic group and 97.2% of the septic group (p > 0.05). Meropenem was most often used as the initial treatment in the non-septic group (20 cases, 18.7%) and septic group (22 cases, 61.1%) (p < 0.0001). Risk factors for septic shock in multivariate analyses were diabetic mellitus (odds ratio (OR) = 3.591, p = 0.0098) and CRP ≥ 10 (OR = 1.057, p = 0.0119) as significant independent factors in this multicenter study. CONCLUSIONS: APN is a common infectious disease, especially in the cases with urinary tract obstruction where patients easily acquire bacteremia or sepsis. Stone-associated obstructed APN can cause fatal septic shock in cases with diabetes and CRP ≥ 10. Further prospective studies will be undertaken to draw definitive conclusions.

Morphological and micro-tomographic study on evolution of struvite in synthetic urine infected with bacteria and investigation of its pathological biomineralization.

Pathological biomineralization in the urinary system leads to urolithiasis. Formation of kidney stones involves a series of events during which they undergo morphological and mineralogical changes. We investigated the mineralization of biogenic struvite (in vitro) and examined the transformation of distinct interior and exterior structure of struvite. In vitro crystallization of struvite was performed in the presence of two bacteria that were originally isolated from the kidney stone patients. Morphological evaluation was carried out using SR-µCT as well as FESEM, XRD and FT-IR. Characteristic internal 3-D morphology and porosity of the stones were studied. For comparison, patient derived struvite stones were used. From the results obtained, we report that the presence of bacteria enhances the crystallization process of struvite in vitro. A series of time-resolved experiments revealed that struvite crystals experienced a significant morphologic evolution from pin pointed structure to X-shaped and tabular morphologies. These X-shaped and unusual tabular habits of struvite resembled biogenic morphologies of struvite. SR-µCT showed similarities between the patient derived and the in vitro derived struvite crystals. In conclusion, these experiments revealed that the bacteria play a major role in the specific morphogenesis of struvite and can able to control the nucleation, modulate crystalline phases, and shape of the growing crystal.

The analysis of microbial spectrum and antibiotic resistance of uropathogens isolated from patients with urinary stones.

PURPOSE: The characteristics and resistance patterns of urine bacteriology in patients with urinary tract stones have not been extensively studied. This study aims to investigate the microbial spectrum and antibiotic resistance of uropathogens isolated from urinary tract infections in patients with urinary stones and provide a basis for appropriate antimicrobial treatments. METHODS: The results of positive bladder midstream urine cultures and their antimicrobial susceptibility were retrospectively analysed from hospitalised patients with diagnosis of urinary calculi and urinary tract infections between January 2010 and December 2015. RESULTS: A total of 3892 samples were analysed during the study period: 2201 were female patients (56.6%) and 1691 were male patients (43.4%). The 4 most common uropathogens were Escherichia coli (48.7%), Klebsiella pneumoniae (10.4%), Enterococcus faecalis (8.7%) and Proteus mirabilis (5.2%). Both E. coli (60.8%) and Proteus mirabilis (7.5%) were higher in female patients than in male patients (32.8%; 2.3%; P < .05). ESBL-positive E. coli accounted for 59.5% of total number of E. coli, while ESBL-positive K. pneumoniae comprised 42.0% of total K. pneumoniae. The majority of uropathogens in patients with stones had high resistance to fluoroquinolones, ceftriaxone, ceftazidime, cefepime, penicillins, sulfonamides and monobactams (resistance >20%). CONCLUSIONS: The microbial spectrum in patients with urinary stones had a complex pattern. The uropathogens showed marked multidrug resistance and a large proportion of the uropathogens were able to produce ß-lactamase.

Evaluation of Biofilm Induced Urinary Infection Stone Formation in a Novel Laboratory Model System.

PURPOSE: Infection stones, which comprise approximately 15% of all urinary tract stones, are induced by infection with urease-positive pathogens. The bacteria in the stone matrix present significant treatment impediments compared to metabolic kidney stones. While much is known about how urinary composition regulates metabolic stone formation, there is a general lack of knowledge of which urinary factors regulate the rate of infection stone formation. Unfortunately more in-depth research into infection stones is limited by the lack of suitable models for real-time study of bacterial biofilm formation and stone formation under varying conditions. MATERIALS AND METHODS: We developed an in vitro model to study infection stone formation. The model closely represents the processes that occur in vivo, including the observed migration of ureolytic bacteria (our culture of Proteus mirabilis) from the bladder to the kidneys, followed by biofilm and stone formation in the kidney. We used scanning electron and confocal laser microscopy, x-ray diffraction, biological counts and dissolved chemical analyses to evaluate the model system. RESULTS: Crystals that formed in the system resembled clinically removed struvite stones in structure and composition. Results showed that the degree of ureolysis required to significantly change urine pH was minimal, bacterial communities inhabited the ureter, and upstream colonization and struvite formation required lag time. CONCLUSIONS: These results have implications for the detection and treatment of struvite stones. Currently this model is being used to study specific urinary factors that regulate struvite formation to identify treatment options, which combined with antibiotics would improve treatment of these stones and decrease recurrence.

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.

Bacterially Induced Formation of Infectious Urinary Stones: Recent Developments and Future Challenges.

Infectious urinary stones make a serious medical problem concerning up to 20% of population. Additionally, recurrence after treatment reaches 50%. The formation of infectious urinary stones is connected with urinary tract infection with various bacteria. These are mainly the bacteria from Proteus species which have been isolated in 70% of bacteriainduced urinary stone cases. These microorganisms produce urease - a bacterial enzyme which plays a principal role in the crystallization process and is one of the main virulence parameters of these bacteria. The most common solid components of infectious urinary stones are the crystals of struvite and amorphous carbonate apatite. The formation of this kind of stones involves two main processes. The first one is the nucleation process of solid phases and the second is the aggregation of the precipitated phases, both crystalline and amorphous. In recent years, both these processes have been deeply investigated. In particular, different active compounds have been reported as potentially novel therapeutic agents to prevent or inhibit the formation of infectious urinary stones. In addition, there is rich scientific evidence regarding the chemical mechanisms of inhibitory effect of these active compounds. In recent years, specific interior and exterior structure of struvite and its porous nature have also been reported. In this article, we summarize and discuss recent development in this field of research. The paper concludes with future goals and challenges.

Treatment of the Infected Stone.

Infected kidney stones refer to stones that form because of urinary tract infections with urease-producing bacteria, secondarily infected stones of any composition, or stones obstructing the urinary tract leading to pyelonephritis. The mainstay of treatment of infection stones is complete stone removal. Kidney stones that obstruct the urinary tract and cause obstructive pyelonephritis are also frequently referred to as infected stones. Obstructive pyelonephritis is a urologic emergency as it can result in sepsis and even death. Infection stones and obstructive stones causing pyelonephritis are different disease processes, and their workup and management are described separately.