Urinary tract infection’s etiopathogenic role in nephrolithiasis formation

Association of health-related quality of life with urinary tract infection among kidney stone formers

Kidney stones and infections significantly affect patients' health-related quality of life (HRQOL); however, the relationship between urinary tract infections (UTIs) and HRQOL in patients with kidney stones remains unclear. This study aimed to investigate the relationship using the validated Chinese version of the Wisconsin Stone Quality of Life questionnaire (C-WISQOL). We prospectively recruited 307 patients with kidney stones to complete the C-WISQOL before and after stone removal. The participants were diagnosed with UTI based on the presence of pyuria or bacteriuria with or without clinical symptoms. The psychometric properties of the C-WISQOL were statistically analyzed. Multivariate linear regression was used to predict the risk factors for impaired HRQOL in patients with stones and UTIs. The questionnaire is a reliable and robust tool for evaluating HRQOL in Chinese-speaking patients with urolithiasis. The UTI and kidney stone co-occurrence was significantly associated with female sex, diabetes mellitus, more previous stone events, higher antibiotic usage, positive stone- or UTI-related symptoms, and postoperative residual stones. The preoperative C-WISQOL scores and improvement in the HRQOL after stone removal in patients clinically diagnosed with UTI were significantly inferior to those in patients without UTI. The regression analyses showed that worse HRQOL was predicted by more previous stone events and positive stone- or UTI-related symptoms. In contrast, the presence of diabetes mellitus and postoperative residual stone fragments predicted a lower improvement in the HRQOL. These findings underscore UTI's harmful impact on perioperative HRQOL in patients with kidney stones and could help strategies benefit those patients.

Analysis of the Components of 236 Cases of Urinary Stones in Xinjiang Uyghur Children

INTRODUCTION

 The aim of the study is to explore the relationship between clinical characteristics and urinary calculus in Xinjiang Uyghur children, and to provide clinical basis for the prevention as well as treatment of urinary stone.

MATERIALS AND METHODS

 In total, 236 urinary tract stone samples were collected from pediatric patients from February 2017 to April 2019, and those samples were analyzed by infrared spectroscopy. Stone compositions were compared with demographic data.

RESULTS

 Among the 236 cases, 166 cases were boys (70.34%) and 70 cases were girls (29.66%), with a male-to-female ratio of 2.37:1. A total of 21 kinds of calculi were detected, including 107 cases with six kinds of simple calculi and 129 cases with 15 kinds of mixed calculi. In this study, magnesium ammonium phosphate hexahydrate was only found in boys, and the difference was statistically significant (6.6 vs. 0.0%, p = 0.037). There were statistical differences in the age distribution of children with ammonium hydrogen urate, calcium oxalate, and other stone components (p < 0.05), while there were no statistical differences in the age distribution of children with apatite carbonate, magnesium ammonium phosphate hexahydrate, and anhydrous uric acid. The results showed that there was a significant difference in the localization of calculi between male and female children (upper urinary tract stones: 78.9 vs. 98.6%, p < 0.001).

CONCLUSION

 Uyghur pediatric patients with urolithiasis were young and the majority of stones was mixed, The main components of calculi were ammonium hydrogen urate, calcium oxalate and apatite carbonate, and there are differences in the localization of calculi between genders.

Investigation of Virulence Genes of the Predominant Bacteria Associated with Renal Stones and their Correlation with Postoperative Septic Complications

Purpose

Nephrolithiasis is a worldwide disease, and 4.7% of the patients may develop postoperative sepsis. Characterization of virulence genes of bacteria associated with renal stones is still lacking in the literature. The study aimed to investigate the virulence genes of the predominant stone bacterial isolate and their association with postoperative septic complications in patients treated with percutaneous nephrolithotomy (PCNL).

Methods

Stone and midstream urine samples were collected from 200 nephrolithiasis patients who underwent PCNL. Microbiological examination and virulence profile were studied for the common bacteria isolated from the stones.

Results

Microbiological analysis revealed that Staphylococcus aureus was the predominant organism in stone samples (42.8%), while Escherichia coli (56.6%) was the dominant pathogen in midstream urine. Eight patients (4%) developed septic complications; stone culture was positive for S. aureus in seven and E. coli in one patient, while all but one had negative midstream urine. The patient with positive midstream urine culture had also S. aureus infection. Detection of virulence genes in S. aureus isolated from stones showed a high positivity of the hemolysine gene hla (93.3%) and adhesion gene fnbA (73.3%), whereas enterotoxin genes (sec and sea) were negative in all S. aureus stone cultures. Moreover, the adhesion genes (fnbB and can), hemolysine gene (hlb), panton-valentine leukocidin (pvl) gene and the enterotoxin gene (seb) were significantly higher in septic patients compared to the non-septic ones (p< 0.05). Interestingly, there was a significant relation between the existence of virulence genes and the resistance of antibiotics (p < 0.05).

Conclusion

There has been a notable shift toward gram-positive organisms (S. aureus) in the stone culture. Moreover, S. aureus virulence genes were significantly attributed to the resistance of some antibiotics and postoperative septic complications, suggesting that the stone culture could be more informative than urine culture, especially in predicting the risk of postoperative sepsis.

Persistent Escherichia coli infection in renal tubular cells enhances calcium oxalate crystal-cell adhesion by inducing ezrin translocation to apical membranes via Rho/ROCK pathway

Recent evidence has suggested that recurrent urinary tract infection (UTI) can cause not only infection stones but also metabolic stones (e.g., those containing calcium oxalate monohydrate or COM). However, precise mechanisms underlying UTI-induced metabolic stones remained unknown. In this study, Escherichia coli, the most common bacterium found in recurrent UTI was used to establish the in vitro model for persistent infection of renal epithelial cells. The promoting effects of persistent E. coli infection on kidney stone formation were validated by COM crystal-cell adhesion assay, followed by immunofluorescence study for changes in surface expression of the known COM crystal receptors. Among the five receptors examined, only ezrin had significantly increased level on the surface of persistently infected cells without change in its total level. Such translocation of ezrin to apical membranes was confirmed by Western blotting of apical membrane and cytosolic fractions and confocal microscopic examination. Additionally, persistent infection increased phosphorylation (Thr567) of ezrin. However, all of these changes induced by persistent E. coli infection were significantly inhibited by small-interfering RNA (siRNA) specific for ezrin or a Rho-associated kinase (ROCK)-specific inhibitor (Y-27632). In summary, this study provides a piece of evidence demonstrating that persistent infection by E. coli, one of the non-urease-producing bacteria, may contribute to COM metabolic stone formation by translocation of ezrin to apical membranes, thereby promoting COM crystal-cell adhesion. Such ezrin translocation was mediated via Rho/ROCK signaling pathway. These findings may, at least in part, explain the pathogenic mechanisms underlying recurrent UTI-induced metabolic kidney stone disease.

Bacterial Effect on the Crystallization of Mineral Phases in a Solution Simulating Human Urine

The effect of bacteria that present in the human urine (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus) was studied under the conditions of biomimetic synthesis. It was shown that the addition of bacteria significantly affects both the phase composition of the synthesized material and the position of crystallization boundaries of the resulting phosphate phases, which can shift toward more acidic (struvite, apatite) or toward more alkaline (brushite) conditions. Under conditions of oxalate mineralization, bacteria accelerate the nucleation of calcium oxalates by almost two times and also increase the amount of oxalate precipitates along with phosphates and stabilize the calcium oxalate dihydrate (weddellite). The multidirectional changes in the pH values of the solutions, which are the result of the interaction of all system components and the crystallization process, were analyzed. The obtained results are the scientific basis for understanding the mechanisms of bacterial involvement in stone formation within the human body and the creation of biotechnological methods that inhibit this process.

Assessing Cost-Effectiveness of New Technologies in Stone Management

Diagnosis, treatment, and follow-up are all influential in determining the overall cost to the health care system for kidney stones. New innovations in the field of nephrolithiasis have been abundant, including disposable ureteroscopes, ultrasound-guided approaches to percutaneous nephrolithotomy, and advanced laser lithotripters. Identifying cost-effective treatment strategies encourages practitioners to be thoughtful about providing value-based high-quality care and remains on important principle in the treatment of urinary stone disease.