Risk factors for development of urinary tract infection in children with nephrolithiasis

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.

Evaluation of quality of renal tract ultrasound scans and reports performed in children with first urinary tract infection

PURPOSE

To determine the quality of renal tract ultrasound (US) imaging records performed in children for evaluation of urinary tract infection (UTI) by multiple professionals with different levels of experience in a dedicated academic children's hospital.

METHODS

Retrospective analysis of US images and reports for children ≤ 13-years with first presentation of a UTI. 9 Operators (6 consultant radiologists and 3 sonographers) were anonymised and the adequacy of their US images and reports were evaluated for the following categories; Image acquisition, Image labelling, Metric labelling, and Final reporting. The frequency of the reporting quality of the elements assessed was compared between radiologists and sonographers using Chi-square or fisher exact test.

RESULTS

Renal tract US studies for 100 children (20 males, 80 females) with first UTI episode were assessed. Mean age was 4.5 ± 3.4 years. 54% of the studies were performed by sonographers and 46% by radiologists. Kidneys and pre-micturition bladder scans were acquired in more than 96% of exams by both sonographers and radiologists. Kidney image and metric labelling was adequate in almost all exams (98-100%) with the exception of plane labelling which was not routinely done by US operators (less than 3%). Sonographers performed consistently better than radiologists in post-micturition bladder scanning, pre- and post-micturition bladder labelling and renal length reporting (p<0.05). Least to be recorded by US operators (both radiologists and sonographers) were doppler scan acquisitions (less than 3%), bladder wall thickness labelling (less than 3%), and renal calculi reporting (less than 1%).

CONCLUSION

The inconsistency of the reporting quality between the different elements assessed highlights the difference in US training and experience received by sonographers and radiologists. A pro-forma structured reporting template may ensure US operators provide consistent, thorough and good quality ultrasound images and reports.

Diagnosis and grading of vesicoureteral reflux on voiding cystourethrography images in children using a deep hybrid model

BACKGROUND AND OBJECTIVE

Vesicoureteral reflux is the leakage of urine from the bladder into the ureter. As a result, urinary tract infections and kidney scarring can occur in children. Voiding cystourethrography is the primary radiological imaging method used to diagnose vesicoureteral reflux in children with a history of recurrent urinary tract infection. Besides the diagnosis of reflux, it is graded with voiding cystourethrography. In this study, we aimed to diagnose and grade vesicoureteral reflux in Voiding cystourethrography images using hybrid CNN in deep learning methods.

METHODS

Images of pediatric patients diagnosed with VUR between 2016 and 2021 in our hospital (Firat University Hospital) were graded according to the international vesicoureteral reflux radiographic grading system. VCUG images of 236 normal and 992 with vesicoureteral reflux pediatric patients were available. A total of 6 classes were created as normal and graded 1-5 patients.

RESULTS

In this study, a hybrid-based mRMR (Minimum Redundancy Maximum Relevance) using CNN (Convolutional Neural Networks) model is developed for the diagnosis and grading of vesicoureteral reflux on voiding cystourethrography images. Googlenet, MobilenetV2, and Densenet201 models are used as a part of the hybrid architecture. The obtained features from these architectures are examined in concatenating process. Then, these features are classified in machine learning classifiers after optimizing with the mRMR method. Among the models used in the study, the highest accuracy value was obtained in the proposed model with an accuracy rate of 96.9%.

CONCLUSIONS

It shows that the hybrid model developed according to the findings of our study can be used in the diagnosis and grading of vesicoureteral reflux in voiding cystourethrography images.

The microbiome in urinary tract infections in children - an update

PURPOSE OF REVIEW

Urinary tract infection (UTI) is one of the most common pediatric infections worldwide. Recently introduced 16S rRNA sequencing allows detailed identification of bacteria involved in UTI on a species-based level. The urogenital microbiome in children is scarcely investigated, with underlying conditions differing from adults. Improvement in diagnostic and therapeutic approaches can help to minimize unnecessary antibiotic treatments, thereby protecting the physiological microbiome.

RECENT FINDINGS

Healthy bladders of children display a distinct microbiome than those of adults. UTI is characterized by changes in bacterial composition, with a high prevalence of Enterobacterales. There is a correlation between bacterial species and the pH of the urine, so a characteristic age-related pathogen pattern can be found due to the acidic urine in infants and more alkaline urine in older children. Recently, new methods were proposed to overcome the suboptimal diagnostic performance of urine cultures and urine dipstick test. This allows precise treatment decisions and helps to prevent chronification of UTI, related voiding dysfunctions and renal scaring, systemic abiosis, and the development of antibiotic resistance.

SUMMARY

Uropathogens involved in UTIs in children should be identified with precision to allow targeted therapeutic decisions. This can also help preventing the destruction of the microbiome homeostasis, which could result in a life-long dysbiosis. New treatment approaches and recolonization with probiotics are necessary due to increasing intrinsic antibiotic resistance of bacteria.

Evaluation of a child with suspected nephrolithiasis

PURPOSE OF REVIEW

As the incidence of nephrolithiasis in children doubles every 10 years it is becoming a common disease associated with significant morbidity along with considerable economic burden worldwide. The aim of this review is to summarize current data on the epidemiology and causes of renal stones in children and to provide a frame for the first clinical evaluation of a child with suspected nephrolithiasis.

RECENT FINDINGS

Dietary and environmental factors are the driving force of changing epidemiology. Diagnosis should be based on medical history, presenting signs, examination, first laboratory and radiological workup. Ultrasound should be the initial diagnostic imaging performed in pediatric patients while low-dose computed tomography is rarely necessary for management. Metabolic factors including hypercalciuria, hypocitraturia, low fluid intake as well as specific genetic diseases should be explored after the resolution of initial signs and symptoms.

SUMMARY

Appropriate initial evaluation, imaging technique, identification of risk factors and other abnormalities are essential for early diagnosis and prevention of stone-related morbidity in children with suspected nephrolithiasis.