Abnormal Development of Microbiota May Be a Risk Factor for Febrile Urinary Tract Infection in Infancy.

Febrile urinary tract infection (fUTI) is common in infants, but specific risk factors for developing it remain unclear. As most fUTIs are caused by ascending infections of intestinal bacteria, dysbiosis-an imbalance in gut microbial communities-may increase fUTI risk. This study was conducted to test the hypothesis that abnormal development of gut microbiota during infancy increases the risk of developing fUTI. Stool samples were collected from 28 infants aged 3-11 months with first-onset fUTI (fUTI group) and 51 healthy infants of the same age (HC group). After bacterial DNA extraction, 16S rRNA expression was measured and the diversity of gut microbiota and constituent bacteria were compared between the two groups. The alpha diversity of gut microbiota (median Shannon index and Chao index) was significantly lower in the fUTI group (3.0 and 42.5) than in the HC group (3.7 and 97.0; p < 0.001). The beta diversity also formed different clusters between the two groups (p < 0.001), suggesting differences in their microbial composition. The linear discriminant analysis effect size showed that the fUTI group proportionally featured significantly more Escherichia-Shigella in the gut microbiota (9.5%) than the HC group (3.1%; p < 0.001). In summary, abnormal gut microbiota development during infancy may increase the risk of fUTI.

Dysbiosis of the gut microbiota in children with severe motor and intellectual disabilities receiving enteral nutrition: A pilot study.

BACKGROUND: Children with severe motor and intellectual disabilities (SMIDs) frequently and continuously receive enteral nutrition and medications and lack adequate exercise, which may lead to dysbiosis, an imbalance in the composition of the gut microbiota. However, studies on the composition of gut microbiota in children with SMIDs are limited. Therefore, we aimed to examine the characteristics of the gut microbiota in children with SMIDs. METHODS: 16S rRNA gene sequencing was performed using fecal samples of 10 children with SMIDs, who received enteral nutrition through a gastric fistula or gastric tube (SMID group: median age, 10.0 years), and 19 healthy children (healthy control [HC] group: median age, 9.0 years). Microbial diversity, microbial composition, and abundance of butyric acid-producing bacteria were compared between the groups. Daily dietary fiber intake in the SMID group was evaluated using questionnaires. RESULTS: The Shannon and Simpson indices (alpha diversity indices) were significantly lower in the SMID group than those in the HC group. Beta diversity analysis identified different clusters. Compared with the HC group, Clostridiales and butyric acid-producing bacteria were less abundant and Bacteroidales were more abundant in the SMID group. Dietary fiber intake in the SMID group was approximately two-thirds of the estimated average requirement for healthy Japanese children. CONCLUSION: Children with SMIDs showed dysbiosis with alteration in the microbial diversity, which could partly be attributed to their low dietary fiber intake. Further studies, with the intervention of prebiotics, probiotics, and synbiotics, are warranted to improve dysbiosis in children with SMIDs.

Accuracy of diagnosing acute kidney injury by assessing urine output within the first week of life in extremely preterm infants.

BACKGROUND: Neonatal acute kidney injury (AKI) is associated with increased mortality and is often assessed with the neonatal modified Kidney Disease: improving Global Outcomes (KDIGO) classification, which uses changes in serum creatinine levels. However, because this classification has many drawbacks, a novel method, the neonatal Risk, Injury, Failure, Loss, and End-Stage Kidney Disease (nRIFLE) classification for diagnosing neonatal AKI according to urine output (UO), was recently proposed. To date, no data on the incidence of AKI according to nRIFLE are available for extremely preterm infants (born at gestational age less than 28 weeks). This study was conducted to clarify the association between incidence of AKI and in-hospital mortality in extremely preterm infants. METHODS: Of 171 extremely preterm infants hospitalized from 2006 to 2020, 84 in whom indwelling bladder catheters were placed for UO measurements within 24 h of life were included. The incidence of AKI was assessed using the nRIFLE classification. In-hospital mortality was compared between patients with AKI and those without it. RESULTS: The incidence of AKI during the first week of life was 56% and that of in-hospital mortality was significantly higher in patients with AKI (25.5%) than in those without it (2.8%). The odds ratio was 12.3 with 95% confidence interval ranging from 1.5 to 100.0. CONCLUSION: The incidence of AKI according to nRIFLE was higher than reported in most previous studies using the neonatal modified KDIGO classification, suggesting that assessment by nRIFLE criteria using UO may improve diagnostic accuracy of AKI in extremely preterm infants.

Association of Neonatal Jaundice with Gut Dysbiosis Characterized by Decreased Bifidobacteriales.

Neonatal jaundice, caused by excess serum bilirubin levels, is a common condition in neonates. Imbalance in the gut microbiota is believed to play a role in the development of neonatal jaundice. Thus, we aimed to reveal the gut microbiota characteristics in neonates with jaundice. 16S rRNA gene sequencing was performed on stool samples collected on day 4 from 26 neonates with jaundice (serum total bilirubin > 15.0 mg/dL) and 17 neonates without jaundice (total serum bilirubin < 10.0 mg/dL). All neonates were born full term, with normal weight, by vaginal delivery, and were breastfed. Neonates who were administered antibiotics, had serum direct bilirubin levels above 1 mg/dL, or had conditions possibly leading to hemolytic anemia were excluded. The median serum bilirubin was 16.0 mg/dL (interquartile range: 15.5-16.8) and 7.4 mg/dL (interquartile range: 6.8-8.3) for the jaundice and non-jaundice groups, respectively. There was no difference in the alpha diversity indices. Meanwhile, in the jaundice group, linear discriminant analysis effect size revealed that Bifidobacteriales were decreased at the order level, while Enterococcaceae were increased and Bifidobacteriaceae were decreased at the family level. Bifidobacteriaceae may act preventatively because of their suppressive effect on beta-glucuronidase, leading to accelerated deconjugation of conjugated bilirubin in the intestine. In summary, neonates with jaundice had dysbiosis characterized by a decreased abundance of Bifidobacteriales.

Fiber-Rich Barley Increases Butyric Acid-Producing Bacteria in the Human Gut Microbiota.

Butyric acid produced in the intestine by butyric acid-producing bacteria (BAPB) is known to suppress excessive inflammatory response and may prevent chronic disease development. We evaluated whether fiber-rich barley intake increases BAPB in the gut and concomitantly butyric acid in feces. Eighteen healthy adults received granola containing functional barley (BARLEYmax®) once daily for four weeks. Fecal DNA before intake, after intake, and one month after intake was analyzed using 16S rRNA gene sequencing to assess microbial diversity, microbial composition at the order level, and the proportion of BAPB. Fecal butyric acid concentration was also measured. There were no significant differences in diversities and microbial composition between samples. The proportion of BAPB increased significantly after the intake (from 5.9% to 8.2%). However, one month after stopping the intake, the proportion of BAPB returned to the original value (5.4%). Fecal butyric acid concentration increased significantly from 0.99 mg/g feces before intake to 1.43 mg/g after intake (p = 0.028), which decreased significantly to 0.87 mg/g after stopping intake (p = 0.008). As BAPB produce butyric acid by degrading dietary fiber, functional barley may act as a prebiotic, increasing BAPB and consequently butyric acid in the intestine.

Superiority of Cystatin C over Creatinine for Early Diagnosis of Acute Kidney Injury in Pediatric Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma.

The exact incidence of acute kidney injury (AKI) during chemotherapy for acute lymphoblastic leukemia (ALL)/lymphoblastic lymphoma (LBL) is unknown. Furthermore, childhood cancer survivors are at risk of AKI-chronic kidney disease transition. Thus, early diagnosis of AKI is crucial. This study aimed to elucidate the incidence of AKI in patients undergoing chemotherapy for pediatric ALL/LBL and to compare the usefulness of serum cystatin C (CysC)- and creatinine (Cr)-based estimated glomerular filtration rate (eGFR) as diagnostic measures. Data of 16 patients with ALL/LBL treated with a total of 75 courses of chemotherapy were retrospectively analyzed. CysC- and Cr-based eGFR were measured before and three times per week during therapy. To calculate the eGFR, an equation for Japanese children was used. AKI was diagnosed when eGFR dropped by ≥ 25% from the highest eGFR value obtained during the latest 2 weeks since the start of chemotherapy. AKI was graded based on the pediatric Risk, Injury, Failure, Loss, End Stage Renal Disease scale. All patients developed AKI during chemotherapy; however, more than 90% of the cases were mild and eventually recovered. No significant differences were found in the incidence of AKI between CysC- and Cr-based eGFR (p = 0.104). The median time to AKI diagnosis was significantly shorter in the CysC-based eGFR than in the Cr-based eGFR (8 vs. 17 days, p < 0.001). In this study, all patients with pediatric ALL/LBL could develop mild AKI during treatment. CysC-based eGFR is a more effective measure than Cr-based eGFR for the early diagnosis of AKI.

Desmopressin response in nocturnal enuresis without nocturnal polyuria in Japanese children.

OBJECTIVES: To evaluate whether the efficacy of desmopressin differs between patients with and without nocturnal polyuria. METHODS: A total of 65 treatment-naïve children with monosymptomatic nocturnal enuresis were enrolled (45 boys; median age 8.9 years). Patients received desmopressin as their first-line treatment. Four different standards were used (Akashi and Hoashi >0.9 mL/kg/sleeping hour; Hamano >[age + 2] × 25 × 130% mL; the International Children's Continence Society >[age + 1] × 30 × 130% mL; and Rittig >[age + 9] × 20 mL) to assess nocturnal polyuria. The effectiveness of desmopressin was compared between patients with and without nocturnal polyuria according to each standard. A response was defined as a reduction in wet nights of >50%. RESULTS: The desmopressin treatment efficacy rate was 54% for polyuria and 67% for non-polyuria patients (P = 0.20), 45% for polyuria and 68% for non-polyuria patients (P = 0.08), 54% for polyuria and 59% for non-polyuria patients (P = 0.80), and 52% for polyuria and 61% for non-polyuria patients (P = 0.61), for the Akashi and Hoashi's, Hamano's, International Children's Continence Society and Rittig's standards, respectively. CONCLUSIONS: No difference was observed in the short-term clinical efficacy of desmopressin regardless of the presence of nocturnal polyuria. Thus, this might be a feasible treatment option for patients with nocturnal enuresis without nocturnal polyuria.

Clinical Significance of Probiotics for Children with Idiopathic Nephrotic Syndrome.

We previously reported that a decrease in butyrate-producing bacteria in the gut is a potential cause of regulatory T cell (Treg) abnormalities in children with idiopathic nephrotic syndrome (INS). Therefore, we hypothesized that administration of butyrate-producing bacteria might reduce INS relapse and the need for immunosuppressants in these patients. Twenty patients in remission from INS (median age 5.3 years, 15 boys) were enrolled in the study and assigned to receive either daily oral treatment with a preparation of 3 g Clostridium butyricum or no probiotic treatment. The number of relapses and requirement for immunosuppressive agents were compared between the two groups. In the probiotic treatment group, analyses of the gut microbiota and Treg measurements were also performed. Probiotic-treated patients experienced fewer INS relapses per year compared with non-probiotic-treated patients (p = 0.016). Further, administration of rituximab in the probiotic treatment group was significantly less frequent compared with the non-probiotic-treated group (p = 0.025). In the probiotic treatment group, analyses before and after probiotic treatment revealed the significant increases in the relative abundance of butyrate-producing bacteria (p = 0.017) and blood Treg counts (p = 0.0065). Thus, oral administration of butyrate-producing bacteria during INS remission may reduce the frequency of relapse and the need for immunosuppressive agents.

Development of the gut microbiota and dysbiosis in children.

The gut microbiota resides in the human gastrointestinal tract, where it plays an important role in maintaining host health. Recent advancements in next-generation sequencing methods have revealed the link between dysbiosis (imbalance of the normal gut microbiota) and several diseases, as this imbalance can disrupt the symbiotic relationship between the host and associated microbes. Establishment of the gut microbiota starts in utero or just after birth, and its composition dramatically changes to an adult-like composition by 3 years of age. Because dysbiosis during childhood may persist through adulthood, it is crucial to acquire a balanced gut microbiota in childhood. Therefore, current studies have focused on the factors affecting the infant gut microbiota. This review discusses recent findings, including those from our studies, on how various factors, including the delivery mode, feeding type, and administration of drugs, including antibiotics, can influence the infant gut microbiota. Here, we also address future approaches for the prevention and restoration of dysbiosis in children.

Reduced urinary excretion of neutrophil gelatinase-associated lipocalin as a risk factor for recurrence of febrile urinary tract infection in children.

BACKGROUND: This study aimed to test the hypothesis that reduced urinary excretions of neutrophil gelatinase-associated lipocalin (NGAL) predispose children to recurrence of febrile urinary tract infection (fUTI). METHODS: Subjects were 38 children diagnosed with fUTI. To examine risk factors for recurrence of fUTI, the subjects were divided into a non-recurrent group and a recurrent group according to the presence or absence of fUTI over 3 years since the first episode. We measured the urinary NGAL levels in patients with fUTI at the non-infected stage in addition to age-matched healthy control children. RESULTS: In a multiple logistic regression analysis, significant differences between the groups were not observed for age, sex, the prevalence of kidney scarring and bladder bowel dysfunction, urinary ß2-microglobulin/creatinine (Cr) level, and serum levels of Cr and Cystatin C, while the recurrent group had significantly more cases with grade III or higher vesicoureteral reflux (p < 0.01). Furthermore, the urinary NGAL/Cr in the recurrent group (median, 3.60 µg/gCr) was significantly lower than that in the non-recurrent group (median, 16.47 µg/gCr; p < 0.01), and age-matched healthy control children (median, 14.14 µg/gCr; p < 0.05). The area under the receiver operating characteristic curve of NGAL/Cr was 0.86 for predicting recurrence of fUTI. A cut-off value of 11.59 µg/gCr had the best accuracy to predict recurrent fUTI yielding a specificity of 78% and a sensitivity of 93%. CONCLUSIONS: Reduced levels of urinary NGAL, which protects against urinary infection, are a risk factor for recurrence of fUTI and could serve as a biomarker.

Idiopathic nephrotic syndrome in children: role of regulatory T cells and gut microbiota.

BACKGROUND: We investigated whether an association exists between regulatory T cells (Tregs) during initial presentation in children with idiopathic nephrotic syndrome (INS) and later development of frequently relapsing INS. METHODS: Blood samples were obtained at onset and at remission from 25 patients (median age, 4.0 years) with INS; eight did not show relapse after initial response (non-relapsing [NR]), whereas 17 showed frequent relapses (frequently relapsing [FR]). Tregs were measured by flow cytometry; increases were compared between groups. Fecal samples were obtained at onset from 20 patients with INS, as well as from 20 age-matched healthy children. Gut microbiota composition was assessed using 16S ribosomal RNA (rRNA) sequencing (ion PGM). RESULTS: The rate of increase in Tregs from onset to remission was significantly lower in the FR group (124.78%) than in the NR group (879.16%; P < 0.001). Additionally, 16S rRNA sequencing of gut microbiota showed that the proportion of butyric acid-producing bacteria was significantly lower in the FR group (7.08%) than in the healthy children (17.45%; P < 0.001). CONCLUSIONS: In children with INS, small increases in Tregs in response to steroid treatment were associated with subsequent increased risk of frequent relapses. In addition, the FR group had a greater degree of dysbiosis at onset. IMPACT: A low rate of Tregs increase is associated with subsequent frequent relapses of INS. The increase in Tregs in response to steroid treatment was small when dysbiosis was present in patients with INS, particularly when the proportion of butyrate-producing bacteria was considerably reduced We presume that improvement of dysbiosis by administration of probiotics and prebiotics may enhance the rate of Tregs' increase, thus preventing frequent relapse.

Our Evolving Understanding of Kawasaki Disease Pathogenesis: Role of the Gut Microbiota.

Kawasaki disease (KD) was first described by Dr. Tomisaku Kawasaki in 1967. The etiology of KD has been studied comprehensively but remains largely unknown. The disease seems to result from the interplay of genetic and environmental susceptibility factors with infectious triggers, followed by a subsequent abnormal immune response characterized by increased levels of inflammatory cytokines and chemokines during the acute phase. Evidence has mounted to suggest that an imbalance between T helper 17 cells (Th17s) and regulatory T cells (Tregs) is associated with aberrant immune responses in KD. Recent advances in culture-independent techniques for detection and identification of intestinal commensal bacteria enabled the discovery that Th17 and Treg differentiation are regulated by short chain fatty acids (SCFAs), in particular butyrate, produced by the gut microbiota. This finding provided a mechanistic link between dysbiosis, defined as changes in the composition of the gut microbiota, and various inflammatory diseases. On this basis, we propose that dysbiosis, with reduced production of SCFAs leading to imbalances of Th17s/Tregs, could be involved in the etiology of KD. A pilot study supported this hypothesis, as only fecal concentrations of butyrate were significantly reduced in KD patients among SCFAs. This evolving perspective prompted us to undertake metagenomic analyses of bacterial DNA from the feces of KD patients who were antibiotic-naïve at diagnosis. Simultaneous measurements of Th17s/Tregs in peripheral blood and SCFA concentrations in feces would provide valuable information regarding the association between dysbiosis and dysregulated immune responses in KD.

Impact of Long-Term Low Dose Antibiotic Prophylaxis on Gut Microbiota in Children.

PURPOSE: We evaluated the effect of long-term low dose antibiotic prophylaxis on children's gut microbiota. MATERIALS AND METHODS: We conducted 16S ribosomal RNA gene sequencing using stool samples from 35 patients younger than 3 years old (median age 5.2 months; male-to-female ratio 17:18) who underwent antibiotic treatment during the acute phase of febrile urinary tract infection. Samples were collected at 5 time points, ie before, during and at 1 to 2, 3 to 4, and 5 to 6 months after febrile urinary tract infection onset and antibiotic treatment. Continuous antibiotic prophylaxis using trimethoprim-sulfamethoxazole was initiated in 23 patients with grade III or higher vesicoureteral reflux and was not administered in 12 patients without reflux. RESULTS: Within 2 weeks after initiation of treatment for febrile urinary tract infection almost all enteric bacteria belonged to the order Lactobacillales, and gut microbiota diversity decreased compared to the pretreatment level (average Shannon index 2.9 before treatment, 1.4 during treatment). The diversity recovered within 1 to 2 months after febrile urinary tract infection onset in both groups. Diversity was maintained during the study period in both groups (p=0.43). A smaller proportion of gut microbiota component belonged to the order Enterobacteriales (p=0.002) in the antibiotic prophylaxis group. CONCLUSIONS: Our results revealed that patients receiving continuous antibiotic prophylaxis had normal gut microbiota diversity, indicating that the effect of trimethoprim-sulfamethoxazole on gut microbiota was insignificant. Furthermore, prophylaxis with trimethoprim-sulfamethoxazole might selectively suppress the growth of bacteria belonging to the order Enterobacteriales, such as Escherichia coli and Klebsiella species, which are the main causative bacteria of febrile urinary tract infections.

Guidelines for the medical management of pediatric vesicoureteral reflux.

Urinary tract infection is a bacterial infection that commonly occurs in children. Vesicoureteral reflux is a major underlying precursor condition of urinary tract infection, and an important disorder in the field of pediatric urology. Vesicoureteral reflux is sometimes diagnosed postnatally in infants with fetal hydronephrosis diagnosed antenatally. Opinions vary regarding the diagnosis and treatment of vesicoureteral reflux, and diagnostic procedures remain debatable. In terms of medical interventions, options include either follow-up observation in the hope of possible spontaneous resolution of vesicoureteral reflux with growth/development or provision of continuous antibiotic prophylaxis based on patient characteristics (age, presence/absence of febrile urinary tract infection, lower urinary tract dysfunction and constipation). Furthermore, there are various surgical procedures with different indications and rationales. These guidelines, formulated and issued by the Japanese Society of Pediatric Urology to assist medical management of pediatric vesicoureteral reflux, cover the following: epidemiology, clinical practice algorithm for vesicoureteral reflux, syndromes (dysuria with vesicoureteral reflux, and bladder and rectal dysfunction with vesicoureteral reflux), diagnosis, treatment (medical and surgical), secondary vesicoureteral reflux, long-term prognosis and reflux nephropathy. They also provide the definition of bladder and bowel dysfunction, previously unavailable despite their close association with vesicoureteral reflux, and show the usefulness of diagnostic tests, continuous antibiotic prophylaxis and surgical intervention using site markings.

Desmopressin response in nocturnal enuresis showing concentrated urine.

BACKGROUND: In Japan, the use of desmopressin (1-desamino-8-D-arginine vasopressin) is only recommended for nocturnal enuresis with unconcentrated first morning urine, which suggests a relative deficiency of antidiuretic hormone secretion during sleep. However, no such limitations have been described in a standardization document of the International Children's Continence Society. We aimed to determine whether desmopressin treatment induces any response in nocturnal enuresis with concentrated first morning urine. METHODS: Outpatients aged 6-15 years who exhibited monosymptomatic nocturnal enuresis were examined. Data were obtained from 41 treatment-naive patients (median age 9.7 years) with nocturnal enuresis, who received desmopressin as their first line of treatment. The patients were divided into two groups demonstrating unconcentrated (osmolality < 800 mOsm/L, Low-Osm group) and concentrated (osmolality ≥ 800 mOsm/L, High-Osm group) first morning urine, respectively; we compared the response to desmopressin treatment between the groups at 1 month after the administration or updosing of desmopressin; responses were defined as partial or complete according to the International Children's Continence Society standards. Mann-Whitney U-tests or Fisher's exact tests were used for analysis. RESULTS: The Low-Osm (median age 9.6 years) and High-Osm groups (median age 9.7 years) had 14 and 27 patients, respectively; the response rates to desmopressin treatment were 64.3% and 59.2%, respectively, indicating no significant differences (P = 0.99). CONCLUSION: Desmopressin treatment may be a feasible option for treating nocturnal enuresis with concentrated first morning urine.