Ting Zhang

Objectives: To analyze clinical epidemiology, serogroup distribution, and antimicrobial resistance (AMR) trends of non-typhoidal Salmonella (NTS) in children to guide empirical therapy and infection control. Methods: We retrospectively analyzed 2145 pediatric NTS cases at Shanghai Children’s Hospital (2014–2025), evaluating serogroups, AMR, and multidrug resistance (MDR) trends. Results: Most patients (73.5%) were Salmonella Enteritidis was the most common serotype (33.3%). Ampicillin resistance remained high (55.0–70.3%), and ceftriaxone resistance reached 25.8% (95/368) in 2025. One carbapenem-resistant NTS isolate was found in each of 2024 and 2025, both belonging to serogroup B. Resistance rates to azithromycin, trimethoprim–sulfamethoxazole, ciprofloxacin, and chloramphenicol were 9.8% (189/1923), 24.4% (523/2143), 9.6% (22/229), and 21.4% (97/454), respectively. Serogroup D showed high ampicillin resistance (81.2%,681/839) but the lowest MDR rate (23.5%,197/839), whereas serogroup C had the highest MDR rate (37.6%, 246/654, p < 0.001). The overall MDR rate was 30.3%. Conclusions: Pediatric NTS infections were seasonal, predominantly affecting children under 5 years. Serogroup C increased over time and carried the highest MDR burden; carbapenem-resistant NTS has emerged. Because susceptibility was classified using year-specific CLSI breakpoints, these historical trends should be interpreted alongside current local susceptibility data. Among tested isolates, serogroup D remained largely susceptible to azithromycin and trimethoprim–sulfamethoxazole.

Background: Intestinal Behçet’s disease is difficult to distinguish from other immune-mediated inflammatory diseases of the gastrointestinal tract such as Crohn’s disease. In recent studies, researchers have reported that multiple monogenic autoinflammatory diseases can mimic Behçet’s disease, making differential diagnosis more challenging. We aim to retrospectively describe the clinical and laboratory features of six pediatric cases with suspected intestinal Behçet’s disease and identify potential monogenic mimics. Methods: This study is a retrospective case series. All patients underwent specialized digestive system evaluation including symptomatology, laboratory examinations, imaging, endoscopy, and pathology. Whole-exome sequencing was conducted to identify potential monogenic mimics. Results: All patients presented with prominent inflammation in the ileocecal region. A likely pathogenic de novo variant in a gene (RELA) associated with a mimicking disease phenotype was identified in one out of six patients, while a second patient had a de novo variant of uncertain significance (VUS) in RELA. A VUS in TNFAIP3 gene was identified in a third patient but was inherited from an unaffected parent. The other three patients either had no detected variant (two cases), or a very likely benign coincidental variant (in CCR1 gene). Conclusions: Monogenic autoinflammatory disorders can be mistaken for Behçet’s disease. We emphasize the importance of genetic testing in pediatric patients with intestinal Behçet’s disease who present with atypical clinical symptoms, but also the importance of using tools to estimate the likelihood of variant pathogenicity, to avoid the overinterpretation of variant significance.

Conjugated linoleic acid (CLA) is a functional lipid and prebiotic with a range of documented physiological benefits. Bifidobacterium breve exhibits excellent capacity for CLA bioconversion, making it a promising microbial resource for enhancing CLA availability in human health. The ability of B. breve to produce CLA is closely linked to its response to linoleic acid (LA)-induced stress, which disrupts arginine biosynthesis and metabolism. However, the role of arginine in CLA bioconversion by B. breve remains poorly understood. In this study, the breast milk-derived strain B. breve SHMB8001 was used to investigate the effects of exogenous L-arginine on bacterial growth and CLA bioconversion, as well as the underlying mechanisms. Results showed that exogenous L-arginine significantly alleviated LA-induced growth inhibition (P < 0.001) and increased CLA-conversion activity by 65%. Gene expression analysis and electrophoretic mobility shift assays (EMSA) revealed that L-arginine modulated the expression of genes involved in transport and ribosome biogenesis, particularly upregulating linoleic acid isomerase (bbi) expression (log₂FC = 7.49) and enhancing the binding of the transcriptional regulator ArgR to a conserved region (72 bp) upstream of the bbi promoter. Moreover, intracellular L-arginine accumulation (up to 298%), protein oligomerization, and molecular docking analyses supported these findings. These results suggest a novel regulatory pathway in B. breve mediated by the "transporter-ArgR-bbi" axis, which regulates CLA bioconversion. These findings have important implications for the development of CLA-producing lactic acid bacteria, amino acid-synergized prebiotics, and infant formula design.

Background: RAS-associated autoimmune leukoproliferative disorder (RALD) is a rare, nonmalignant lymphoproliferative disorder characterized by splenomegaly, autoimmune cytopenia, monocytosis, and somatic RAS pathway mutations. Severe hepatic failure is an uncommon manifestation. Here, we report a critically ill infant with a diagnosis of RALD who presented with fulminant liver failure. Case report: A 9-month-old girl presented with recurrent infections, lymphadenopathy, massive hepatosplenomegaly, cytopenia, coagulopathy, and early-onset liver failure. Disseminated Talaromyces marneffei infection was confirmed by two sets of peripheral blood cultures. Whole-exome sequencing (WES) identified a heterozygous KRAS c.351A>C (p.Lys117Asn, K117N) variant located in the GTP-binding domain. The heterozygous state and clinical context are consistent with a somatic mutation in a subset of hematopoietic cells, rather than a germline variant. The patient died two days after admission despite antibiotics and maximal supportive care, including plasma exchange and intravenous immunoglobulin. Conclusion: This case illustrates that RALD-associated immune dysregulation served as the underlying root cause, on the basis of which a disseminated opportunistic infection developed as the direct cause of the fatal deterioration, revealing a potential link between oncogenic RAS signaling and innate immune dysregulation. It underscores the urgency of early genetic screening in infants with unexplained hepatitis and systemic inflammation, while advocating for novel therapeutic strategies targeting RAS/MAPK pathways.

Introduction: Pediatric aplastic anemia (AA), a rare and potentially fatal disease, demonstrates significant heterogeneity in pathogenesis, disease severity, therapeutic regimens, and clinical outcomes. Methods: In this study, clinical features and outcomes of 70 children with AA, including severe AA (SAA, n = 30), very severe AA (vSAA, n = 21) and nonsevere AA (nSAA, n = 19), were retrospectively analyzed, with a median follow-up of 60.7 months (range, 0.4-136.5 months). Results: Patients with nSAA were mainly treated with cyclosporine A, whereas SAA/vSAA patients primarily received allogeneic hematopoietic stem cell transplantation (HSCT) followed by standard immunosuppressive therapy (IST). Ultimate therapy regimens differed significantly between patients with SAA/vSAA and nSAA ( p = 0.001). SAA/vSAA group exhibited a higher overall response rate at the 2-year follow-up (85.5% vs. 55.6%, p = 0.019). The 2-year overall survival (OS) and event-free survival (EFS) for the entire cohort were 97.1% and 48.5%, respectively. In patients with SAA/vSAA, HSCT was associated with higher and faster cumulative complete response (CR) rate ( p < 0.0001) and superior EFS ( p = 0.0297) compared with IST. Two IST-resistant patients were observed to achieved CR with eltrombopag (EPAG) salvage therapy. Discussion: pediatric AA carries excellent OS but suboptimal EFS. HSCT tends to yield more favorable EFS compared with IST in SAA/vSAA patients, and EPAG may act as an effective salvage option for appropriately selected IST-resistant individuals. Further multicenter prospective research is warranted prior to implementing these findings in routine clinical practice.

Anelloviruses dominate the human plasma virome, yet their lifespan dynamics and relationships with the immune system are unclear. We integrated metagenomics with cytokines, HERV-K, and CMV profiling across 405 individuals (0-100 years) and found that prevalence, abundance, and diversity varied non-linearly with age and by sex. Alphatorqueviruses accumulated progressively with age, while betatorqueviruses and gammatorqueviruses displayed biphasic, female-specific patterns. Alphatorquevirus species diversity had significant inflection points at ages 54-58 years in females. We identified a stable core of 12 age-uniform species, with their abundance trajectories diverging significantly by sex. Male bias in anellovirus metrics widened with age, and community dispersion reversed across lifespan. CMV IgG titers correlated significantly with anellovirus genus richness. In young adult females, anellovirus ORF1 was associated with IL-1β. These findings suggest altered anellovirus ecology as a correlate of age-related immune changes, positioning these viruses as strong indicators of immune status and offering new perspectives on age-modulated host-virus dynamics.

The gut virome is an emerging but underexplored component of the human microbiota, especially in pediatric Crohn’s disease (CD). This study aimed to characterize the fecal virome in children with CD and evaluate its association with clinical response to infliximab (IFX) therapy. A total of 85 participants, including 60 pediatric CD patients and 25 healthy controls (HC), were recruited. Among the CD patients, 53 received ≥3 IFX infusions, 41 achieved remission (IFX-R), and 12 did not (IFX-NR). Viral-like particles in fecal samples were enriched and profiled by metagenomic sequencing, while bacterial communities were assessed via 16S rRNA gene sequencing. Pediatric CD patients exhibited significantly reduced viral richness and altered viral community compared to HCs. Functional analyses revealed that CD patients exhibit a shift in fecal virome function from DNA repair to viral replication and assembly. Trans-kingdom correlations were disrupted in CD, particularly between Torque teno viruses and beneficial bacteria, such as Blautia . An integrated machine learning model combining viral and bacterial markers achieved a certain level of diagnostic accuracy for pediatric CD (area under the curve [AUC] = 89.3%). IFX treatment influences the gut virome, with remission associated with higher abundances of Microviridae and Siphoviridae , while Anelloviridae , Myoviridae, and Podoviridae were enriched in IFX-NR at baseline. These findings suggest the virome as a potential biomarker for predicting clinical outcome in pediatric CD, offering a novel avenue for disease diagnosis and personalized treatment strategies. IMPORTANCE: Crohn’s disease (CD) in children poses a growing clinical challenge, with increasing incidence and variable response to biologic therapies such as infliximab (IFX). While gut bacterial dysbiosis has been extensively studied, the role of the gut virome in pediatric CD remains largely unexplored. This study provides the first longitudinal characterization of the fecal virome in children with CD undergoing IFX therapy. We reveal distinct viral community patterns, functional alterations, and virus-bacteria interactions in pediatric CD patients. Notably, integration of virome and bacteriome profiles enhances diagnostic accuracy, offering a promising avenue for predictive biomarker development. Furthermore, virome changes may be associated with the IFX treatment outcomes in children with CD. These findings highlight the gut virome as a critical but overlooked dimension of host-microbiome interactions in pediatric CD, with potential implications for personalized therapy and mechanistic understanding of treatment resistance.

Objective The rising incidence of pediatric Clostridioides difficile infection (CDI) and its nonspecific clinical presentation pose a significant diagnostic challenge. Current methods (e.g., NAATs, toxin tests) fail to distinguish active infection from asymptomatic colonization reliably. This review assesses the potential of fecal immunological markers to improve the differential diagnosis of pediatric CDI. Methods We synthesized current literature on the epidemiology and diagnostic challenges of pediatric CDI, the limitations of existing diagnostic strategies, and the evidence for fecal immunological markers—including inflammatory mediators, antimicrobial peptides, and immunoglobulins—in distinguishing CDI from non-CDI diarrhea. Results Fecal immunological markers, such as IL-8, IL-1β, calprotectin, and human defensin-5, reflect intestinal mucosal inflammation and the host response during CDI. Elevated IL-8 and IL-1β are associated with disease severity, while fecal calprotectin > 500 µg/g shows high specificity for CDI and predicts recurrence risk. Dynamic changes in sIgA correlate with mucosal immunity and relapse. CDI exhibits a distinct “hyper-inflammatory” profile dominated by IL-1β/IL-8, contrasting with the Th1/interferon-driven response typical of viral diarrhea. However, variability in assay methods, lack of pediatric reference thresholds, and insufficient validation in diverse cohorts limit current clinical applicability. Conclusions Fecal immunological markers represent a promising shift toward a host-focused diagnostic approach for pediatric CDI. Future efforts should prioritize standardized assays, multi-marker panels, and well-designed prospective studies in children to validate their role in guiding diagnosis and personalized management.

Clostridioides difficile infection (CDI) imposes a substantial clinical burden in paediatric populations. However, the high prevalence of asymptomatic colonization, especially in children under 2 years of age, complicates the distinction between true infection and non-pathogenic carriage. This diagnostic uncertainty hinders appropriate treatment decisions and complicates infection prevention efforts. A 6-year retrospective cohort study was performed at Shanghai Children’s Hospital to characterize the epidemiology and clinical features of CDI and asymptomatic colonization in paediatric patients. Stool specimens were cultured for C. difficile , and isolates underwent whole-genome sequencing to perform multilocus sequence typing, identify SNPs and characterize functional gene content via Clusters of Orthologous Groups (COG) analysis. Mutations in genes associated with toxin production were analysed to assess genetic differences between clinical isolates from infected patients and asymptomatic carriers. In addition, comparative genomic analysis was performed to assess variations in virulence-associated genes, antimicrobial resistance (AMR) genes and genes involved in quorum sensing (QS). Colonization factors (CFs) were also characterized to elucidate potential mechanisms differentiating asymptomatic colonization from symptomatic infection. And we conducted in vitro experiments on toxin B-variant strains. A total of 23 sequence types (STs) were identified among isolates from 39 asymptomatic carriers and 61 symptomatic patients, with greater ST diversity observed in the infection group compared to the colonization group. COG analysis demonstrated an increased representation of uncharacterized functional categories in the infection group, suggesting a potential role for novel genes in pathogenesis. Patterns of virulence factor presence, AMR genes and QS gene distribution were comparable between the two groups, as were mutations in toxin regulation genes. Notably, six isolates belonging to ST37 and ST81, characterized by the absence of tcdA and presence of tcdB , exhibited a high frequency of mutations. In vitro experiments demonstrated that these strains exhibited higher biofilm formation capacity and elevated transcriptional levels of both tcdB and spoA . Additionally, no significant differences were detected in the distribution of CFs. Our findings contribute to the growing understanding of the genomic determinants and their functional roles underlying paediatric CDI severity, providing more evidence for improved diagnostic and therapeutic strategies.