Resumo Introdução: Espécies de Moraxella, embora raras em infecções associadas à diálise peritoneal (DP), são patógenos estabelecidos. Moraxella catarrhalis causa infecções respiratórias, frequentemente associadas à produção de β-lactamase. Seu papel na DP merece investigação. Métodos: Buscou-se nas bases PubMed e Google Scholar casos de infecções por Moraxella em DP. Critérios de inclusão: diagnóstico de peritonite ou infecção no local de saída confirmados por cultura. Analisaramse dados demográficos, clínicos, microbiologia, resistência, terapêutica e desfechos. Resultados: Catorze casos de peritonite relacionada à Moraxella em pacientes em DP foram identificados entre 1987 e 2024, a partir de 13 estudos, sem relatos de infecções no local de saída. A idade média foi 56 anos; a nefropatia diabética foi a condição de base mais comum (quatro casos). M. catarrhalis (n = 6) e Moraxella osloensis (n = 5) foram os patógenos mais frequentes, com crescimento bacteriano apoiado em meios de cultura, seguido de identificação por perfis bioquímicos ou sistemas automatizados (n = 10), e técnicas confirmatórias avançadas empregadas quando relatadas. A apresentação clínica incluiu dor abdominal, febre e turbidez do líquido de diálise. A maioria dos isolados mostrou suscetibilidade a cefalosporinas, aminoglicosídeos e fluoroquinolonas. A maior parte dos pacientes (86%) manteve os cateteres após tratamento adequado, geralmente com administração intraperitoneal de cefalosporinas, com resolução completa dos sintomas em poucos dias. O prognóstico geral foi favorável, sem mortalidade. Conclusões: Espécies de Moraxella, embora raras, devem constar no diagnóstico diferencial das infecções relacionadas à DP. Sua identificação por técnicas avançadas permite tratamento eficaz e desfechos favoráveis, frequentemente sem necessidade de remoção do cateter.

INTRODUCTION:Moraxella species, although infrequent in peritoneal dialysis (PD)-associated infections, are established pathogens. Moraxella catarrhalis is recognized as a cause of upper and lower respiratory tract infections and is increasingly associated with β-lactamase production. The role of Moraxella species in PD-related infections warrants further investigation. METHODS:A comprehensive search of PubMed and Google Scholar was conducted for cases of PD-associated infections caused by Moraxella. Inclusion criteria required a diagnosis of peritonitis or exit-site infection confirmed by culture. Demographic data, clinical presentation, microbiological identification, antimicrobial resistance, therapeutic regimens, and outcomes were analyzed. RESULTS:Fourteen cases of Moraxella-related peritonitis in PD patients were identified between 1987 and 2024 from 13 studies, with no reports of exitsite infections. The mean age was 56 years; diabetic nephropathy was the most common underlying condition (four cases). M. catarrhalis (n = 6) and Moraxella osloensis (n = 5) were the most frequent pathogens. The most commonly reported methods were bacterial growth in culture media, followed by species identification using biochemical profiling or automated systems (n = 10), and advanced confirmatory techniques. Clinical presentation included abdominal pain, fever, and clouding of the dialysis fluid. Most isolates were susceptible to cephalosporins, aminoglycosides, and fluoroquinolones. The majority of patients (86%) retained their catheters after appropriate treatment, usually with intraperitoneal cephalosporins, achieving complete symptom resolution within a few days. Overall prognosis was favorable, with no mortality. CONCLUSION:Moraxella species, although rare, should be considered in the differential diagnosis of PD-associated infections. Identification using advanced techniques allows effective treatment and favorable outcomes, often without the need for catheter removal.

Peritoneal dialysis (PD)-related infections due to nontuberculous Mycobacteria (NTM) are rare in children and adolescents but appear to be increasingly recognized. To better understand the clinical profile, characteristics, management and outcomes of these infections, we conducted a systematic review of pediatric cases reported in the literature. We identified 25 episodes in 23 patients under the age of 18, drawn from 19 studies. The mean age was 7.35 years with a slight male predominance. The most common underlying condition leading to end stage renal disease and initiation of PD, was congenital anomalies of the kidney and urinary tract, particularly hypoplastic or dysplastic kidneys. Clinical manifestations were non-specific, often including fever, abdominal pain and cloudy effluent. Among the reported cases 52% presented with peritonitis, 36% with exit site infection and 12% had both. Mycobacterium abscessus and Mycobacterium fortuitum emerged as the most prevalent species, each accounting for a comparable proportion of the recovered isolates. Notably, Mycobacterium chelonae was the most frequent isolated specie among infants. Diagnosis was frequently delayed and treatment required prolonged antibiotic regimens. Catheter removal was performed in almost all cases, while most patients were temporarily switched to hemodialysis. Mortality rate was low approaching 4%. These findings underscore the need for heightened clinical suspicion, early diagnosis and aggressive management to improve outcomes in pediatric patients with PD-related infections due to NTM.

Peritoneal dialysis (PD)-associated peritonitis in children represents a complex interplay between microbial virulence, host immune activation and progressive peritoneal membrane remodeling. It should not be viewed solely as an acute infectious episode, but as a process unfolding within a chronically conditioned immune environment shaped by prolonged exposure to glucose-based dialysis solutions, oxidative stress and persistent biofilm formation on the Tenckhoff catheter. Mesothelial cells act as immunologically active sentinel cells, recognizing pathogen-associated molecular patterns through Toll-like receptors and related innate pathways. Subsequent activation of nuclear factor kappa B, inflammasome signaling and neutrophil extracellular trap formation further amplifies local inflammatory responses. Repeated inflammatory stimulation promotes mesothelial-mesenchymal transition, angiogenesis and extracellular matrix deposition driven by transforming growth factor beta 1 and interconnected profibrotic networks. In pediatric patients, prolonged PD vintage during critical stages of growth may intensify cumulative structural injury and increase the risk of ultrafiltration failure or encapsulating peritoneal sclerosis. Emerging strategies targeting inflammation, fibrosis and biofilm persistence, together with earlier molecular risk detection, may support preservation of the peritoneal membrane. A unified host-pathogen framework may therefore deepen pathophysiological insight and facilitate more individualized therapeutic strategies in pediatric PD.

Background/Objectives: Hepatocyte nuclear factor 1 beta (HNF1B)-associated disease is a major monogenic cause of pediatric cystic kidney disease. This study characterized the clinical, genetic, renal, and extrarenal spectrum of HNF1B-associated disease in a nationwide Greek pediatric cohort, with emphasis on renal functional variability during childhood. Methods: In this retrospective multicenter cohort study, 20 children aged <18 years with molecularly characterized HNF1B-associated disease were identified from eight pediatric nephrology centers across Greece. Clinical, genetic, laboratory, imaging, and kidney function data were analyzed. Estimated glomerular filtration rate (eGFR) was assessed at diagnosis and latest follow-up, and genotype–phenotype comparisons were performed. Results: Median age at diagnosis was 5.0 years. Copy-number variants were identified in 12 patients (60.0%), including ten 17q12 microdeletions and two whole-gene HNF1B deletions, while eight patients (40.0%) carried intragenic variants. Renal cysts were present in 95.0% of patients, hyperechogenic kidneys in 70.0%, and congenital anomalies of the kidney and urinary tract (CAKUT) in 20.0%. Hypomagnesemia was observed in 25.0% of patients, while hyperuricemia was identified in 29.4% of those with available measurements. Longitudinal eGFR data were available for 19 patients. Over a median follow-up of 5.0 years, mean eGFR remained largely unchanged (84.5 ± 19.8 vs. 84.0 ± 16.7 mL/min/1.73 m2); however, substantial interindividual variability was observed. No statistically significant genotype–phenotype associations were identified, although hypomagnesemia was more frequent among patients with deletion-type defects. Conclusions: This nationwide Greek pediatric cohort highlights the marked phenotypic heterogeneity of HNF1B-associated disease, characterized by predominant structural renal abnormalities and relatively stable kidney function during childhood. Larger studies are needed to better define genotype-specific outcomes.

Background/Objectives: Pediatric IgA nephropathy (IgAN) is often considered to have a favorable early course. However, its progression is variable, and the prognostic value of histopathological classifications, such as MEST-C, remains incompletely defined in children. This study aimed to characterize clinicopathological features and the early disease course in pediatric IgAN and to descriptively examine histopathological findings and clinical outcomes. Methods: This retrospective, single-center study included children with biopsy-confirmed IgAN diagnosed between 2016 and 2025. Clinical, laboratory, and histopathological data were collected, and biopsies were assessed using the Oxford MEST-C classification. Follow-up data, including estimated glomerular filtration rate (eGFR), were analyzed descriptively, with follow-up extending from diagnosis to early 2026. Results: Fourteen patients were included, showing heterogeneous clinical presentations. Mesangial hypercellularity was observed in all cases (100%), with frequent endocapillary hypercellularity (78.6%) and segmental sclerosis (57.1%), consistent with a predominance of active lesions. Over a median follow-up of approximately five years, renal function remained stable in 57.1% of patients, declined in 21.4%, and improved in 14.3%, indicating variability in renal function during follow-up and potential reversibility in a subset of patients. One patient (7.1%) developed severe acute kidney injury requiring temporary dialysis, followed by full recovery. Given the descriptive design and limited sample size, no conclusions regarding associations between histopathological findings and renal outcomes can be drawn. Conclusions: Within this small cohort, pediatric IgAN showed variable renal function courses ranging from stability to decline or partial recovery. These findings should be considered descriptive and hypothesis-generating, supporting longitudinal monitoring in larger pediatric cohorts.

Recurrent urinary tract infections (UTIs) are common in children and may lead to long-term renal complications, especially in those with vesicoureteral reflux (VUR). Concerns about antibiotic resistance and side effects of prolonged antibiotic use underscore the need for safe, non-antibiotic alternatives. This prospective, self-controlled observational study evaluated a standardized combination of cranberry extract (36 mg proanthocyanidins daily), probiotics (Lactobacillus rhamnosus and Bifidobacterium longum), and vitamin C (250 mg daily) in 39 children aged 3-16 years, including a subgroup with mild-to-moderate VUR. UTI recurrence was compared before and after the 12-month study period. The supplement was administered for 6 months, followed by a 6-month observation period. Microbiological analyses assessed pathogen distribution. Safety and tolerability were monitored. The intervention significantly reduced UTI recurrence, with median episodes decreasing from 3 to 0 in children without VUR (p < 0.001) and from 2 to 0 in children with VUR (p < 0.05). Overall, 27 of 39 participants (69.2%) remained infection-free throughout follow-up, while the remaining participants experienced a reduced number of UTI episodes compared with the pre-supplementation period. Escherichia coli remained the predominant pathogen, while the diversity of other uropathogens changed minimally, indicating fewer infections rather than microbial shifts. The supplement was well tolerated, with mild gastrointestinal symptoms in 5 of 39 participants (12.8%) and no serious adverse events. Subgroup analyses showed consistent benefit across age and sex, with children having higher baseline UTI frequency experiencing the greatest reduction. A multi-component supplement of cranberry, probiotics, and vitamin C effectively reduced recurrent pediatric UTIs, decreased overall infection burden, preserved E. coli as the main pathogen, and was safe and well tolerated, including in children with mild-to-moderate VUR.

Recurrent urinary tract infections in children represent a common clinical challenge associated with repeated antibiotic exposure and rising antimicrobial resistance. These limitations have intensified interest in non-antibiotic preventive strategies, particularly nutritional bioactives capable of modulating host–microbe interactions. This review provides a clinically oriented synthesis of current evidence on dietary and nutraceutical interventions for the prevention of recurrent pediatric urinary tract infections. Particular attention is given to the limited availability of high-quality pediatric-specific evidence and the heterogeneity of current clinical data. It focuses on cranberry-derived type A proanthocyanidins, probiotics, selected micronutrients and D-mannose. Key mechanistic pathways are also highlighted, including inhibition of uropathogen adhesion, microbiome-mediated biotransformation of bioactives into anti-inflammatory metabolites, and modulation of host immune and epithelial responses within the gut–bladder axis. Available evidence suggests that cranberry products standardized to deliver approximately 36 mg/day of type A proanthocyanidins may reduce recurrence risk, whereas probiotics and vitamins A, C, and D may provide adjunctive benefits through microbiome modulation and enhancement of innate immune responses. However, substantial heterogeneity in study design, variability in formulations and dosing, and the limited availability of high-quality pediatric randomized trials remain important limitations. Building on current evidence, we propose a pragmatic multimodal framework for non-antibiotic prevention in children that integrates nutritional strategies with clinical risk stratification and individualized care, with particular attention to bioavailability, dose standardization and pediatric-specific factors such as age-related microbiome maturation. Future research should prioritize biomarker-driven endpoints, microbiome-informed stratification and adequately powered pediatric studies to define responders and optimize personalized prevention strategies.

Pediatric nephrology is shifting from broad phenotype-based labels toward molecularly defined, genotype-guided diagnosis and management. Childhood kidney disorders are enriched for monogenic causes, yet persistent microscopic hematuria, bilateral kidney cysts, steroid-resistant nephrotic syndrome, and thrombotic microangiopathy may represent shared endpoints of biologically distinct mechanisms. Using these four scenarios, this narrative review illustrates how structured phenotyping, pedigree analysis, biochemical evaluation, and appropriately selected genomic testing can establish etiology, revise diagnoses, and guide clinical decision-making. Molecular diagnosis may support early nephroprotection, prevent ineffective immunosuppression, reveal tumor or extrarenal risks, enable mechanism-based therapy, and optimize transplantation planning. It also enables cascade testing, reproductive counseling, presymptomatic evaluation of relatives, and safer assessment of living-related donors. Genomic findings, however, require clinical context. Variants must be evaluated against gene–disease validity, inheritance, segregation, molecular mechanism, and phenotype, while variants of uncertain significance should not independently determine treatment or donor eligibility. Negative or inconclusive findings should prompt phenotypic reassessment, evaluation of analytical limitations, targeted studies, and periodic genomic reanalysis. Emerging genome and long-read sequencing, multiomics, artificial intelligence, and RNA-based therapeutics may further expand precision care, but rigorous interpretation, equitable access, appropriate counseling, and multidisciplinary collaboration remain essential. Precision nephrology derives value not from identifying variants alone, but from converting molecular etiology into safer, anticipatory, and individualized care.

Primary hyperoxaluria type 1 (PH1) is a rare autosomal recessive disorder that causes progressive renal failure, nephrolithiasis, and nephrocalcinosis in children. It is characterized by hepatic overproduction of oxalate. Conventional management, which involves combined liver-kidney transplantation, vitamin B6 supplementation, and intense hydration, does not address the underlying metabolic defect for most patients and it generally provides only supportive care. The first approved disease-modifying treatment for pediatric PH1 is Lumasiran, a small interfering RNA (siRNA) therapeutic. By specifically inhibiting the hepatic glycolate oxidase mRNA, Lumasiran lowers the production of oxalate at its origin. Along with fewer kidney stone events and stabilization of nephrocalcinosis, clinical trials (ILLUMINATE-A/B/C) showed significant decreases in urinary oxalate excretion. The most frequently reported adverse event is mild injection-site reactions, which are generally well tolerated. The molecular mechanism, pharmacokinetics, and clinical effectiveness of Lumasiran in children with PH1 are compiled in this review. We go over possible long-term safety concerns, the impact of early intervention on renal outcomes, and the function of siRNA therapies in pediatric precision medicine. Furthermore, we highlight Lumasiran's importance as a model for targeted treatment in uncommon pediatric kidney diseases by considering it in the larger context of RNAi-based therapies. A paradigm shift in pediatric nephrology is signaled by Lumasiran, which changes the therapeutic approach from supportive care to precision, targeted medicine. Further research and empirical data will clarify its long-term advantages, the best ways to treat it, and the possible use of siRNA technologies for other genetic renal disorders.

Background/Objectives: Opportunistic infections remain clinically important after kidney transplantation and may contribute to morbidity and graft dysfunction in pediatric recipients. Data regarding their timing, spectrum and clinical course in children remain limited. Methods: We retrospectively reviewed pediatric kidney transplant recipients followed at a single tertiary center between 2014 and 2024. Demographic and clinical characteristics, infection type, timing after transplantation, management and outcomes were recorded. Infection incidence was assessed at the patient level, whereas pathogen distribution and timing were analyzed per infection episode. Results: Twenty-seven pediatric kidney transplant recipients were included, with a mean follow-up of 5.6 years. Ten patients (37.0%) developed at least one clinically significant opportunistic infection, and one patient experienced two distinct episodes, resulting in 11 infection events. BK virus was the most frequent pathogen, followed by fungal infections and cytomegalovirus (CMV). Five episodes (45.5%) occurred within the first post-transplant year, whereas six (54.5%) occurred later during follow-up. Late infections included CMV, fungal infections, BK virus and West Nile virus. Most infections resolved after targeted management without persistent graft impairment; however, one patient developed biopsy-confirmed BK virus-associated nephropathy with sustained graft dysfunction. No infection-related mortality was observed. Conclusions: Clinically significant opportunistic infections occurred both early and late after pediatric kidney transplantation, with more than half of all infectious episodes developing beyond the first post-transplant year. Although overall outcomes were favorable, BK virus-associated nephropathy remained clinically relevant because of its impact on graft function.

Background/Objectives: Fungal peritonitis is a severe complication of peritoneal dialysis (PD) associated with catheter removal, technique failure, and increased mortality. Although Candida albicans was traditionally the predominant pathogen, non-albicans Candida (NAC) species are increasingly reported. This review summarizes the epidemiology and outcomes of PD-associated NAC peritonitis. Methods: A systematic review was performed following PRISMA guidelines. PubMed/MEDLINE, Scopus, and Google Scholar were searched (January 1990–March 2026) for NAC peritonitis studies. Case reports and series with species-level identification were included. Results: 31 studies met the inclusion criteria, comprising 25 individual case reports and 6 case series, totaling 89 NAC isolates. Candida parapsilosis was the most frequently reported species (n = 50), followed by Candida tropicalis (n = 15). Other pathogens included Candida glabrata, Candida guilliermondii, and several rare NAC species. Fluconazole was the most commonly used initial antifungal therapy. Catheter removal was performed in most cases, with the majority of patients requiring transition to hemodialysis. Overall mortality was 20% among individual case reports vs. 24% across case series. Species-specific differences were observed: C. parapsilosis and C. guilliermondii were generally associated with favorable outcomes, whereas infections involving C. glabrata and other emerging NAC species more frequently required treatment escalation and were linked to poorer outcomes. Conclusions: NAC species are an important cause of fungal peritonitis in PD patients and show considerable heterogeneity in clinical outcomes and antifungal susceptibility. Early species-level identification and prompt catheter removal remain essential for optimal management.

Peritoneal dialysis (PD)-related infections caused by rare pathogens are heterogeneous and clinically challenging, and available evidence is largely limited to isolated reports that hinder comparative interpretation. We conducted a controlled pooled narrative synthesis with exploratory comparative analyses of previously published, author-derived literature, designed to compare clinical outcomes across rare pathogen groups using a consistent analytical framework rather than a systematic review or meta-analysis. Infectious episodes were categorized into four groups: Gram-positive bacteria, Gram-negative bacteria, nontuberculous Mycobacteria (NTM) and fungal pathogens (Aspergillus spp.). Primary outcomes were catheter removal and infection-related mortality, while secondary outcomes were analyzed descriptively. In total, 135 infectious episodes were included (17 Gram-positive, 39 Gram-negative, 25 NTM and 55 Aspergillus). Catheter removal occurred in 11.8% of Gram-positive, 12.8% of Gram-negative, 95.8% of NTM and 85.5% of Aspergillus infections, while infection-related mortality was observed only in NTM (4.0%) and Aspergillus infections (38.2%). Exploratory comparisons suggested a gradient of severity across pathogen categories. In conclusion, rare PD pathogens show distinct, pathogen-specific outcome patterns. Rather than a validated prognostic model, we propose descriptive, hypothesis-generating pathogen-based severity tiers that may support early risk appraisal, guide timely decisions regarding catheter salvage versus early removal, and facilitate more tailored, pathogen-informed management in high-risk infections.

BACKGROUND:Type IV collagen-related nephropathies comprise a spectrum of inherited glomerular disorders, with Alport disease representing the most severe phenotype. In children, these conditions often present with isolated hematuria, while progressive kidney disease typically develops later. Early diagnosis may therefore enable timely family-based risk assessment and preventive nephrological care. METHODS:We retrospectively analyzed data about 18 children with persistent microscopic and/or macroscopic hematuria who underwent targeted next-generation sequencing of COL4A3, COL4A4, and COL4A5, with variant classification according to ACMG criteria. Clinical data and family history were reviewed, and cascade testing of relatives was performed when feasible. RESULTS:Pathogenic COL4A5 variants were identified in 12 patients (67%) and likely pathogenic COL4A5 variants in two additional patients. Pathogenic variants in COL4A4 and COL4A3 were detected in one patient each, while two patients harbored only COL4A3 variants of uncertain significance. Glycine-substituting missense variants were the most frequent molecular defect (9/18 cases), whereas loss-of-function variants were identified in 7/18 patients, including variants in COL4A5, COL4A3 and COL4A4. Proteinuria was present in 44% of patients, while kidney function was preserved at diagnosis. A positive family history of kidney disease or hematuria was present in 61% of families, and kidney failure in adult relatives in 28%. Cascade testing identified additional genetically affected relatives in all tested families. CONCLUSIONS:Hematuria in pediatric age may represent an early manifestation of COL4A-related nephropathies and should prompt genetic evaluation. Molecular diagnosis in childhood facilitates identification of affected relatives and supports early surveillance and family-based preventive strategies.

Background/Objectives: Preterm birth interrupts nephrogenesis during a critical developmental window, resulting in reduced nephron endowment and lifelong renal vulnerability. Evidence indicates that individuals born preterm are at increased risk for hypertension, albuminuria, and chronic kidney disease (CKD) across the life course. This review synthesizes current evidence linking prematurity with adverse renal outcomes, explores key pathophysiological mechanisms, and discusses emerging biomarkers together with therapeutic strategies. Methods: This comprehensive review integrates evidence from clinical cohort studies, population-based registries, meta-analyses and experimental models. Factors such as neonatal acute kidney injury (AKI), nephrotoxic exposures and cardiometabolic interactions were integrated to provide a life-course perspective. Results: Preterm birth leads to reduced nephron endowment, compensatory glomerular hypertrophy, and hyperfiltration, which predispose to progressive nephron loss. Postnatal factors, including neonatal AKI, inflammation, nephrotoxic medications, and later cardiometabolic stress, act as cumulative “hits”, accelerating renal injury trajectories. Clinical studies demonstrate a higher prevalence of reduced estimated glomerular filtration rate, albuminuria, elevated blood pressure, and smaller kidney volumes from childhood into adulthood. Emerging biomarkers such as cystatin C, alongside imaging-based estimates of nephron endowment, may enhance early risk stratification. Conclusions: Preterm birth represents an independent, lifelong risk factor for CKD through combined developmental and postnatal mechanisms. Structured long-term surveillance and early preventive strategies are essential to preserve renal reserve in this population. Advances in biomarker-guided monitoring and targeted interventions may enable earlier identification of high-risk individuals and support precision approaches to nephroprotection after prematurity.