Regulatory T and B cells in pediatric Henoch-Schönlein purpura: friends or foes?

BACKGROUND AND OBJECTIVES: Henoch-Schönlein purpura (HSP) is the most common immunoglobulin A-mediated systemic vasculitis in childhood. We studied immune dysregulation in HSP by analyzing regulatory T (Treg), T helper 3 (Th3), and regulatory B cell (Breg) subpopulations that might intervene in immune activation, IgA production, and HSP clinical manifestations. METHODS: This prospective study included 3 groups of children: 30 HSP on acute phase, 30 HSP on remission, and 40 healthy controls (HCs) matched on age. Treg, Breg, and Th3 were analyzed by flow cytometry. Serum immunoglobulin and cytokine levels were quantified by ELISA and Luminex. RESULTS: Treg frequencies were higher in acute HSP than in remitting HSP and HCs (6.53% [4.24; 9.21] vs. 4.33% [3.6; 5.66], p = 0.002, and vs. 4.45% [3.01; 6.6], p = 0.003, respectively). Activated Th3 cells (FoxP3 + Th3 cells) tend to be more abundant in HSP than in HCs (78.43% [50.62; 80.84] vs. 43.30% [40.20; 49.32], p = 0.135). Serum IgA, IL-17, and latency-associated peptide (a marker of the anti-inflammatory cytokine TGF-beta production) were significantly and inflammatory cytokines TNF-alpha, IL-1-beta, and IL-6 were non-significantly higher in HSP than HCs. Bregs were identical between the groups, but, in patients with renal impairment, Breg percentage was lower compared to those without. Treg removal in PBMC culture resulted in an increase in IgA production in HSP proving a negative regulatory role of Tregs on IgA production. CONCLUSIONS: In pediatric HSP, immune activation persists in spite of an increase in Th3 and Tregs. Th3 could be involved in IgA hyperproduction, inefficiently downregulated by Tregs. Lack of Bregs appears linked to renal impairment.

Anti-infective treatment of gastro-intestinal tract infections in children.

Gastroenteritis is most often viral in origin and Rotavirus and Norovirus most frequently implicated in young children. Stool-based multiplex Polymerase Chain Reaction (PCR) can detect bacteria, viruses or parasites that may or may not be responsible for gastroenteritis (colonization). While the etiological profile of these digestive infections has greatly benefited from PCR, in the absence of underlying pathologies the presence of potential pathogens does not justify anti-infectious treatment. Indeed, very few bacterial causes require antibiotic treatment, apart from shigellosis, severe forms of salmonellosis and a few Campylobacter sp. infections. The development of antibiotic resistance in Salmonella sp., Shigella sp. and Campylobacter sp. is a cause for concern worldwide, limiting therapeutic options. The antibiotics proposed in this guide are in line with the joint recommendations of the European Society of Pediatric Infectious Diseases and the European Society of Pediatric Gastroenterology and Nutrition. Azithromycin is preferentially used to treat infections with Shigella sp. or Campylobacter sp. Ceftriaxone and ciprofloxacin are recommended for salmonellosis requiring antibiotic therapy. Empirical treatments without bacterial identification are not indicated except in cases of severe sepsis or in subjects at risk (e.g., sickle-cell disease). Metronidazole should be prescribed only for acute intestinal amebiasis after microbiological confirmation.

Diagnostic accuracy of SARS-CoV-2 rapid antigen test from self-collected anterior nasal swabs in children compared to rapid antigen test and RT-PCR from nasopharyngeal swabs collected by healthcare workers: A multicentric prospective study.

Testing for SARS-CoV-2 is central to COVID-19 management. Rapid antigen test from self-collected anterior nasal swabs (SCANS-RAT) are often used in children but their performance have not been assessed in real-life. We aimed to compare this testing method to the two methods usually used: reverse transcription polymerase chain reaction from nasopharyngeal swabs collected by healthcare workers (HCW-PCR) and rapid antigen test from nasopharyngeal swabs collected by healthcare workers (HCW-RAT), estimating the accuracy and acceptance, in a pediatric real-life study. From September 2021 to January 2022, we performed a manufacturer-independent cross-sectional, prospective, multicenter study involving 74 pediatric ambulatory centers and 5 emergency units throughout France. Children ≥6 months to 15 years old with suggestive symptoms of COVID-19 or children in contact with a COVID-19-positive patient were prospectively enrolled. We included 836 children (median 4 years), 774 (92.6%) were symptomatic. The comparators were HCW-PCR for 267 children, and HCW-RAT for 593 children. The sensitivity of the SCANS-RAT test compared to HCW-RAT was 91.3% (95%CI 82.8; 96.4). Sensitivity was 70.4% (95%CI 59.2; 80.0) compared to all HCW-PCR and 84.6% (95%CI 71.9; 93.1) when considering cycle threshold <33. The specificity was always >97%. Among children aged ≥6 years, 90.9% of SCANS-RAT were self-collected without adult intervention. On appreciation rating (from 1, very pleasant, to 10, very unpleasant), 77.9% of children chose a score ≤3. SCANS-RAT have good sensitivity and specificity and are well accepted by children. A repeated screening strategy using these tests can play a major role in controlling the pandemic.

Evaluation of post-infectious inflammatory reactions in a retrospective study of 3 common invasive bacterial infections in pediatrics.

Infectious diseases can result in unanticipated post-infectious inflammatory reactions (PIIR). Our aim was to explore PIIR in 3 frequent pediatric bacterial invasive infections in France by a retrospective monocentric study. We included children hospitalized between 2003 and 2012 for Streptococcus pneumoniae (SP), Neisseria meningitidis (NM), or Streptococcus pyogenes invasive infections. The PIIR had to have occurred between 3 and 15 days without fever despite an individually tailored antibiotic therapy. A descriptive analysis was carried out to determine PIIR risk factors. We included 189 patients, of whom 72, 79, and 38 exhibited invasive infections caused by S pyogenes, SP, and NM, respectively. The mean age was 44 months. PIIR were observed in 39 cases, occurring after a median of 8 days (5-12), with a median duration of 3 days (2-6). Fever, arthritis, and pleural effusion were observed in 87%, 28.2%, and 25.6%, respectively. In multivariate analysis, PIIR were associated with pleuropneumonia, hospitalization in an intensive care unit (ICU), and elevated C-reactive protein (CRP). PIIR were observed in 20% of children after SP, NM, or S pyogenes invasives infections. Their occurrence was associated with the initial severity but not the etiological microorganism. Further studies are warranted to confirm these findings.

A Non-Invasive Neonatal Signature Predicts Later Development of Atopic Diseases.

Background: Preterm birth is a major cause of morbidity and mortality in infants and children. Non-invasive methods for screening the neonatal immune status are lacking. Archaea, a prokaryotic life domain, comprise methanogenic species that are part of the neonatal human microbiota and contribute to early immune imprinting. However, they have not yet been characterized in preterm neonates. Objective: To characterize the gut immunological and methanogenic Archaeal (MA) signature in preterm neonates, using the presence or absence of atopic conditions at the age of one year as a clinical endpoint. Methods: Meconium and stool were collected from preterm neonates and used to develop a standardized stool preparation method for the assessment of mediators and cytokines and characterize the qPCR kinetics of gut MA. Analysis addressed the relationship between immunological biomarkers, Archaea abundance, and atopic disease at age one. Results: Immunoglobulin E, tryptase, calprotectin, EDN, cytokines, and MA were detectable in the meconium and later samples. Atopic conditions at age of one year were positively associated with neonatal EDN, IL-1ß, IL-10, IL-6, and MA abundance. The latter was negatively associated with neonatal EDN, IL-1ß, and IL-6. Conclusions: We report a non-invasive method for establishing a gut immunological and Archaeal signature in preterm neonates, predictive of atopic diseases at the age of one year.

Meconial Methanobrevibacter smithii suggests intrauterine methanogen colonization in preterm neonates.

To understand the dynamics of methanogens in the human intestinal microbiota, we investigated the presence of methanogens in meconium using a polyphasic approach including microscopy and PCR-sequencing in 33 meconium samples collected from 33 pre-term neonates, in accordance with current ethics regulation. In the presence of negative controls, 90.9% samples were real-time PCR-positive for methanogens and 69.7 % were PCR-sequencing positive, identified as Methanobrevibacter (M.) smithii. Further, auto-fluorescent analysis detected methanogens in the two meconium samples analyzed, with a morphology suggesting M. smithii. Multispacer Sequence Typing found M. smithii genotypes ST1 and ST2, previously described as intestinal microbiota inhabitants. C-section delivery and non-use of peripartum antibiotics significantly correlated with PCR-detection of methanogens in meconium. These data position M. smithii among the early inhabitants of the human gut, detectable immediately after birth and suggest the contribution of methanogens to the perinatal development of intestinal microbiota and physiology.

Regulatory T cell/Th17 balance in the pathogenesis of paediatric Behçet disease.

OBJECTIVES: Behçet disease (BD) is a chronic systemic inflammatory disorder of unknown aetiology. The aim of this study was to determine the orientation of T cell subpopulations in paediatric BD and more precisely to look for a regulatory T lymphocyte (Treg)/Th17 imbalance. METHODS: T cell subpopulations were analysed by flow cytometry in the peripheral blood of paediatric patients with acute BD (aBD; n = 24), remitting BD (rBD; n = 12) and in healthy controls (HCs; n = 24). Tregs (CD4+CD25hiCD127-/loFoxp3+), activated Tregs (GITR, LAP, CTLA-4 and HLA-DR expression), CD4+ and CD8+ T cells producing IFN-γ (Th1 and Tc1) or IL-17 (Th17 and Tc17) under polyclonal (OKT3/IL-2) or antigenic (Streptococcus sanguis KTH-1 peptides and heat shock protein 60) stimulation were enumerated. RESULTS: Th17 (1.9- and 5.1-fold) and Tc17 (4.0- and 2.0-fold) frequency under mitogenic stimulation was significantly increased in aBD and rBD patients as compared with HCs. Th17 frequency under antigenic stimulation was also higher in patients than in HCs. The percentage and number of Tregs and activated Tregs in patients and in HCs were similar. However, when Tregs were removed, antigen-driven differentiation into Th1 and Th17 was significantly boosted in BD but not in HC CD4+ T cells. CONCLUSION: There is a bias towards Th17 polarization in aBD and rBD in children. Although we did not observe an increase in the number of Tregs in these patients, their Tregs limit CD4+ T cell differentiation into Th1 and Th17 cells. Thus, in paediatric BD, Tregs seem to incompletely counterbalance a Th17 orientation of the Th cell response.

Near-Infrared Spectroscopy: A Tool for Diagnosing Necrotizing Enterocolitis at Onset of Symptoms in Preterm Neonates with Acute Gastrointestinal Symptoms?

OBJECTIVE: In premature neonates, bloody stools and/or abdominal distension with feeding intolerance may be inaugural signs of necrotizing enterocolitis (NEC). We assessed the ability of near-infrared spectroscopy (NIRS) to distinguish those neonates with NEC soon after the occurrence of these symptoms. STUDY DESIGN: We prospectively collected NIRS measurements of abdominal and cerebral regional tissue oxygen saturation (r-SO2), with values masked by an opaque cover. Two physicians, blinded to the NIRS data, determined whether the gastrointestinal symptoms were related to NEC 10 days after symptom onset. RESULTS: Forty-five neonates with mean (standard deviation [SD]) gestational, birth weight and postnatal ages of 31 (3.9) weeks, 1,486 (794) g, and 18 (14) days were enrolled over 30 months. Gastrointestinal symptoms were related to NEC in 23 patients and associated with other causes in 22. Analysis of the 48 hours of monitoring revealed comparable abdominal r-SO2 and splanchnic-cerebral oxygenation ratio (SCOR) in patients with and without NEC (r-SO2: 47.3 [20.4] vs. 50.4 [17.8], p = 0.59, SCOR: 0.64 [0.26] vs. 0.69 [0.24], p = 0.51). Results were unchanged after NIRS analysis in 6-hour periods, and restriction of the analysis to severe NEC (i.e., grade 2 and 3, 57% of the NEC cases). CONCLUSION: In this study, NIRS monitoring was unable to individualize NEC in premature infants with acute gastrointestinal symptoms.

Reference Values for Abdominal Circumference in Premature Infants.

Objectives: Abdominal distention is a common indicator of feeding intolerance in premature newborns. In the absence of a precise definition, abdominal distention and its degree are highly subjective. The aim of this study was to construct references and smoothed percentiles for abdominal circumference (AC) and AC to head circumference (HC) ratio (AC/HC) in infants born between 24 weeks and 34 weeks of gestational age. Methods: ACs and HCs were collected weekly in eutrophic premature infants without congenital abdominal or cerebral malformation. AC and HC charts were modeled using the LMS method, excluding measures associated with abdominal distention at clinical examination or intracranial abnormality at cerebral ultrasounds. Changes in AC and AC/HC over time were studied by repeated-measures analysis using mixed-effects linear models. Results: A total of 1,605 measurements were made in 373 newborns with a mean gestational age of 31 [29-33] weeks and mean birth weight of 1,540 [1,160-1,968] g. Of these measurements, 1,220 were performed in normal conditions. Gestational age, postnatal age, singleton status, and respiratory support were significantly associated with AC and AC/HC. LMS curves were generated according to gestational age groups and postnatal age, with coherent profiles. AC/HC was 0.91 [0.86-0.95] in absence of abdominal distention. It was higher in cases of abdominal distention (0.95 [0.89-1.00], p < 0.001) and necrotizing enterocolitis (0.98 [0.93-1.07], p < 0.001). Conclusions: References constructed for AC and AC/HC might be used to assess feeding tolerance in premature infants. AC/HC was more relevant than AC to rationalize the diagnosis of abdominal distention.

Assessment of anti-infective medication adherence in pediatric outpatients.

The objective of this pilot study was to assess the overall adherence rate of the pediatric population to anti-infective drugs prescribed for acute infection at hospital discharge and to identify risk factors for non-adherence behavior. Pediatric patients discharged from a French university hospital with at least one oral drug prescription for acute infection were included for 3 months. Medication adherence and antibiotic knowledge were assessed through data collected by calling the parents. Overall adherence was assessed according to seven items: medication order filling, administered dose, time of intake, frequency of doses, medication omission, dose modification, and length of treatment. Seventy-five patients were included, and 63 interviews were exploited. The median age was 1.4 years, IQR = [0.7; 3.3]. Overall adherence to anti-infective agents concerned 34.9% of patients. The most frequently prescribed antibiotics were amoxicillin (29.3%), amoxicillin associated with clavulanic acid (25.3%), cotrimoxazole (18.7%), and cefixime (12.0%). A lack of parents' anti-infective knowledge was associated with non-adherence to anti-infective drugs.Conclusion: Two-thirds of outpatients were non-adherent to anti-infectives in acute infectious diseases. The misunderstanding of anti-infective treatment could be a risk factor for non-adherence. Implementation of preventive actions such as therapeutic education or pharmaceutical counseling at hospital discharge could improve adherence to anti-infective agents. What Is Known: • Non-adherence to anti-infective drugs involves the emergence and spread of antibiotic resistance. • Very few studies have assessed medication adherence in acute infectious diseases in pediatrics after hospital discharge. What Is New: • Only 35% of children were overall adherent to anti-infective drugs in acute infectious disease after hospital discharge. • Most patients (89%) had a good primary adherence but very few (40%) had good secondary adherence mainly due to dose omission and dose modification.

Survey of Staphylococcus aureus in a general pediatric population and focus on isolates with three clinically relevant toxin-encoding genes.

BACKGROUND: In children, surveys on Staphylococcus aureus have focused on specific infections, situations or strains but no study has so far given an overview on S. aureus isolation without any selection. Here, we describe the overall bacteriological and clinical characteristics of S. aureus isolation in children, with a special focus on isolates harbouring tst, sea, and/or luk-PV genes, respectively, encoding the three clinically relevant toxins: toxic shock syndrome toxin-1, enterotoxin A and Panton-Valentine leukocidin. METHODS: Data associated with S. aureus isolation were reviewed: isolation site, infection status, tst, sea and luk-PV genes, antimicrobial susceptibility pattern, agr typing. RESULTS: Three hundred and seventy-seven isolates retrieved from 328 children during S. aureus infection (55.2%) or colonisation (44.8%) were included. tst, sea and luk-PV genes were amplified in 14.3, 9.5 and 5.8% of the isolates, respectively. These isolates were significantly more frequently retrieved during infection (69.1%) than colonisation but differences were observed according to isolation site. Methicillin-resistance was found in 7.2% of the isolates, 78% of which harboured ≥ 1 of the targeted toxin-encoding genes. CONCLUSIONS: This first comprehensive study of S. aureus in children showed S. aureus to be mainly retrieved during infection and a high rate of colonisation, not limited to the nasopharynx. Predominant infections were skin and soft tissue infections where tst was most frequently detected. luk-PV was most commonly detected during bone and joint infections. Isolates harbouring targeted toxin-encoding genes were significantly associated with infections but a quarter of children were asymptomatic carriers representing a reservoir for dissemination of isolates with virulence potency.

Reentry Tachycardia in Children: Adenosine Can Make It Worse.

OBJECTIVES: We report on a rare but severe complication of adenosine use in a child with reentry tachycardia. METHODS AND RESULTS: Treatment with adenosine, which is the standard medical therapy of atrioventricular reentry tachycardia, led to the development of an irregular wide complex tachycardia, caused by rapid ventricular response to atrial fibrillation. The girl was finally stabilized with electrical cardioversion. We analyze the pathomechanism and discuss possible treatment options. CONCLUSIONS: Atrial fibrillation, as well as its conduction to the ventricles, can be caused by adenosine. Rapid ventricular response in children with Wolff-Parkinson-White syndrome is more frequent than previously believed. A patient history of atrial fibrillation is a contraindication for cardioversion with adenosine and needs to be assessed in children with reentry tachycardia. High-risk patients may potentially profit from prophylactic comedication with antiarrhythmic agents, such as flecainide, ibutilide, or vernakalant, before adenosine administration.

A possible role for IL-17 in Clarkson's disease.

INTRODUCTION: Systemic capillary leak syndrome (SCLS) is a rare disease characterized by recurrent episodes and a triad of "leak attacks": hypovolemic shock, generalized edema, hemoconcentration and paradoxical hypoalbuminemia. CASE STUDY AND DISCUSSION: Here we report a case of pediatric idiopathic SCLS with an episode of cough and fever followed two days later by myalgia, livedo, acrocyanosis, and five days later by edema, tachycardia, hypotension, and generalized tonic-clonic seizure. Moreover, we provide evidence for an LPS-induced overproduction of interferon-gamma and interleukin-17 by the patient's peripheral blood mononuclear cells one year after the attack. CONCLUSION: This observation suggests the involvement of IL-17 in the pathogenesis of this disease.

Pediatric Miller Fisher Syndrome Complicating an Epstein-Barr Virus Infection.

BACKGROUND: Miller Fisher syndrome, a variant of Guillain-Barré syndrome, is an acute inflammatory demyelinating polyradiculoneuropathy that may occur weeks after a bacterial or viral infection. Campylobacter jejuni and Haemophilus influenzae are frequently reported etiological agents. PATIENT DESCRIPTION: We describe a boy with Miller Fisher syndrome following Epstein-002DBarr virus primary infectious mononucleosis. He presented with bilateral dysfunction of several cranial nerves and hyporeflexia of the limbs but without ataxia. Miller Fisher syndrome was confirmed by the presence of anti-GQ1b antibodies in a blood sample. Epstein-Barr virus was identified by polymerase chain reaction and serology. CONCLUSION: Epstein-Barr virus should be considered as a Miller Fisher syndrome's causative agent. The physiopathology of this condition may involve cross-reactive T-cells against Epstein-Barr virus antigens and gangliosides.

What to expect from molecular tools for non-documented pediatric infectious diseases.

OBJECTIVE: Evaluation of the contribution of molecular tools to the overall diagnosis of infectious diseases in children. METHODS: Results of 16S rDNA analysis (179 children; 228 specimens), combined to specific amplification of Kingella kingae (126 children; 166 osteoarticular specimens), were retrospectively analyzed for samples with inconclusive cultures. RESULT: The overall positive yield in diagnosis was 12.8% of the patients for 16S rDNA PCR, 40.5% for K. kingae PCR and 45.2% for combined use of both methods. Results were related to clinical and biological data (direct examination, certainty/uncertainty of clinical diagnosis, fever, biological markers, previous antibiotics), and to the number of samples analyzed per patient, allowing the identification of specific situations with significant contribution of PCR methods. CONCLUSION: Molecular techniques constitute valuable tools to improve the bacterial infection diagnosis in children; however, specific indications, dedicated samples, and number of analyzed samples per patient are key points to optimize their contribution.

Staphylococcus aureus in a neonatal care center: methicillin-susceptible strains should be a main concern.

BACKGROUND: In the context of a methicillin-susceptible Staphylococcus aureus (MSSA) outbreak, we aimed to improve our knowledge of S. aureus (SA) epidemiology in the neonatal care center (NCC) of a tertiary care teaching hospital. METHODS: We performed a complete one-year review of SA carrier, colonized or infected patients. Monthly prevalence and incidence of SA intestinal carriage, colonization and infection were calculated and the types of infection analysed. During the MSSA outbreak, strains were studied for antimicrobial resistance, content of virulence genes and comparative fingerprint in Pulsed-Field Gel Electrophoresis. Hand hygiene and catheter-related practices were assessed by direct observational audits. Environmental investigation was performed in search of a SA reservoir. RESULTS: Epidemiological analyses showed 2 or 3 prevalence peaks on a background of SA endemicity. In the NCC, during 2009, overall MSSA prevalence did not decrease below 5.5%, while mean MRSA prevalence was about 1.53%. Analysis of infection cases revealed that the outbreak corresponded to the emergence of catheter-related infections and was probably related to the relaxation in infection control practices in a context of high colonization pressure. Health care workers' white coats appeared as a potential environmental reservoir that could perpetuate SA circulation in the ward. CONCLUSION: This report emphasizes the importance of integrating MSSA along with methicillin-resistant SA in a program of epidemiological surveillance in the NCC.

Validation of nosocomial infection in neonatology: a new method for standardized surveillance.

BACKGROUND: Nosocomial infections (NIs) are a leading cause of mortality and morbidity in premature infants. We present a new method for detecting and confirming NIs in a neonatal intensive care unit. METHODS: Newborns with birth weight < 1,500 g or gestational age (GA) < 33 weeks were included prospectively over 2 years in a single-center tertiary neonatal intensive care unit. The computerized physician order entry system (CPOE) generated alerts when antibiotics were prescribed for at least 5 consecutive days and these cases were reviewed by an expert group following international recommendations. RESULTS: Four hundred sixty-one neonates were included, with a mean GA of 30 weeks (range, 26-32 weeks) and mean birth weight 1,270 g (range, 950-1600 g). The CPOE flagged 158 cases of potential NI, 85.1% of which were classified as true NI and 14.9% of which were false positive. Incidence and device-associated nosocomial bloodstream infection rates were 21.9% and 10.8 per 1,000 central venous catheter days, respectively. GA ≤ 28 weeks (odds ratio, 2.18; 95% confidence interval, 1.2-4) and > 7 central venous catheter days (odds ratio, 1.47; 95% confidence interval, 1.3-1.7) were independently associated with the risk of nosocomial bloodstream infection. CONCLUSION: Combining CPOE and interdisciplinary review may improve the accuracy of NI recording in a neonatal intensive care unit.