Rapid detection of S. pyogenes and S. pneumoniae in pleural fluid for diagnosis of parapneumonic empyema.

The aim of this study was to assess the reliability of rapid antigen detection tests (RADT) for Streptococcus pyogenes (GAS) and Streptococcus pneumoniae on pleural fluid samples for diagnosis of parapneumonic effusion/empyema (PPE) and their potential for improving pathogen identification rates. Sixty-three pleural samples were included from 54 patients on which GAS and S. pneumoniae RADT (BinaxNOW), culture, 16S rRNA PCR, and S. pneumoniae-specific PCR were performed. GAS RADT showed a sensitivity of 95.2% and a specificity of 100%. Pneumococcal RADT showed a sensitivity of 100% and specificity of 88.6%. Both RADT increased the pathogen identification rate in PPE compared to culture.

Spiroplasma infection as a cause of severe congenital keratouveitis, cataract and glaucoma.

BACKGROUND: Only seven cases of ocular Spiroplasma infection have been reported to date, all presenting as congenital cataracts with concomitant intraocular inflammation. We describe the first case of Spiroplasma infection initially presenting as a corneal infiltrate. CASE PRESENTATION: A 1-month-old girl was referred for a corneal infiltrate in the left eye. She presented in our hospital with unilateral keratouveitis. Examination showed a stromal corneal infiltrate and dense white keratic precipitates in the left eye. Herpetic keratouveitis was suspected and intravenous acyclovir therapy was initiated. Two weeks later, the inflammation in the left eye persisted and was also noticed in the right eye. Acute angle-closure glaucoma and a cataract with dilated iris vessels extending onto the anterior lens capsule developed in the left eye. The inflammation resolved after treatment with azithromycin. Iridectomy, synechiolysis and lensectomy were performed. Bacterial metagenomic sequencing (16 S rRNA) and transmission electron microscopy revealed Spiroplasma ixodetis species in lens aspirates and biopsy. Consequently, a diagnosis of bilateral Spiroplasma uveitis was made. CONCLUSIONS: In cases of congenital cataract with concomitant intraocular inflammation, Spiroplasma infection should be considered. The purpose of this case report is to raise awareness of congenital Spiroplasma infection as a cause of severe keratouveitis, cataract and angle-closure glaucoma in newborns. Performing molecular testing on lens aspirates is essential to confirm diagnosis. Systemic macrolides are suggested as the mainstay of treatment.

Favorable course of leptospirosis and hantavirus-induced acute tubulointerstitial nephritis under corticosteroid treatment.

BACKGROUND: We present two children with acute tubulointerstitial nephritis (ATIN) caused by leptospirosis in a 12-year-old boy and hantavirus in a 10-year-old girl. The role of glucocorticoids in the management of ATIN triggered by infectious agents is unclear. CASE-DIAGNOSIS/TREATMENT: Both children were hospitalized with jaundice, elevated serum creatinine, and thrombocytopenia. There was no oliguria or hypertension. Urine analysis revealed tubular proteinuria. Kidney biopsy was performed on one patient and showed tubulointerstitial inflammation with mild mesangial proliferation. Both patients were treated with glucocorticoids in view of deteriorating kidney function with respective serum creatinine values of 5.2 and 4.1 mg/dl. Both children exhibited an excellent clinical and biochemical response to treatment. Neither of the patients required dialysis. Positive serology test results indicated a recent leptospirosis and hantavirus infection. CONCLUSIONS: Leptospirosis and hantavirus associated ATIN share common clinical and biochemical features. Due to the low incidence in Europe these infectious causes of kidney dysfunction may be overlooked. Glucocorticoids may be considered in the management of ATIN.

Administration of ciprofloxacin through a nasogastric tube in pediatric oncology and stem cell transplantation patients.

Pediatric oncology and hematopoietic stem cell transplantation patients are facing many gastrointestinal side effects of chemotherapy, including nausea, vomiting, mucositis, and diarrhea. International guidelines advise early enteral tube feeding as the first option of nutritional support in children undergoing myeloablative hematopoietic stem cell transplantation. When using enteral feeding tubes for nutritional purposes as well as drug administration, some pharmaceutical, nursing, and technical issues have to be taken into account. Ciprofloxacin is a fluoroquinolone, widely used because of its broad spectrum antimicrobial activity and favorable pharmacokinetic properties. However, its co-administration with polyvalent cations (as present in enteral feeding) makes the absorption of ciprofloxacin more difficult and may alter the pharmacokinetic parameters. Literature data are conflicting on how long the enteral feeding should be discontinued for patients receiving ciprofloxacin via an enteral feeding tube, ranging from 2 h before to 6 h after the administration of ciprofloxacin. Our research question was guided by challenges and concerns of nurses about the delay time between ciprofloxacin administration and restart of the enteral feeding without compromising the nutritional intake of the children. Our guideline was adapted, nurses were instructed accordingly, and patient leaflets with correct information were created.

Mental Health Outcomes Among Parents of Children With a Chronic Disease During the COVID-19 Pandemic: The Role of Parental Burn-Out.

OBJECTIVE: The COVID-19 pandemic and associated quarantine measures highly impacted parental psychological well-being. Parents of children with chronic diseases might be specifically vulnerable as they already face multiple challenges to provide adequate care for their child. The research questions of the current study were twofold: (a) to examine whether parents of children with a chronic disease experienced more anxiety and depression compared to parents of healthy children and (b) to examine a series of risk factors for worsened well-being (i.e., depression, anxiety, and sleep problems), such as sociodemographic variables, COVID-19-specific variables (i.e., financial worries, living space, and perceived quality of health care), and parental psychological experiences (i.e., parental burn-out and less positive parenting experiences). METHODS: Parents of children with a chronic disease (i.e., the clinical sample; N = 599 and 507 for Research Questions 1 and 2, respectively) and parents of healthy children (i.e., the reference sample: N = 417) filled out an online survey. RESULTS: Findings demonstrated that the parents in the clinical sample reported higher levels of anxiety than parents in the reference sample. Analyses within the clinical sample indicated that COVID-19-specific stressors and parental psychological experiences were associated with higher levels of anxiety, depression, and sleep problems. Mediation analyses furthermore indicated that the association of COVID-19-specific stressors with all outcome measures was mediated by parental burn-out. CONCLUSIONS: Parents of children with a chronic disease constitute a vulnerable group for worse well-being during the current pandemic. Findings suggest interventions directly targeting parental burn-out are warranted.

Development and validation of an LC tandem MS assay for the quantification of ß-lactam antibiotics in the sputum of cystic fibrosis patients.

OBJECTIVES: Antibiotic therapy is of vital importance for the control of infectious exacerbations in cystic fibrosis (CF) patients. However, very little is known regarding the fraction of systemically administered antibiotics reaching the lower respiratory tract secretions. We developed and validated a method to measure the concentrations of piperacillin, ceftazidime, meropenem and aztreonam in CF sputum, and present the validation data. METHODS: Ultra-performance LC coupled to tandem MS was used. A single sample can be measured in 2.5 min with multiple reaction monitoring in positive electrospray ionization mode. Deuterated internal standards were used and a concentration range of 0.7-160 mg/L was covered. The method was validated according to the EMA guideline on analytical method validation. RESULTS: The boundaries within which a reliable measurement in CF sputum can be performed were determined. A few constraints are linked to the instability of the antibiotics in sputum. Piperacillin showed limited stability at room temperature and during freeze-thaw cycles. Autosampler instability was observed after 15 h for aztreonam at low concentrations. CONCLUSIONS: The method allows a reliable measurement of the selected antibiotics, if precautions are taken regarding the limited stability of piperacillin at room temperature. Due to freeze-thaw instability, piperacillin should always be analysed on the day of sampling. Quick review of the analytical data and reanalysis are needed as low concentrations of aztreonam are not stable in the autosampler.

Risk factors and impact of allergic bronchopulmonary aspergillosis in Pseudomonas aeruginosa-negative CF patients.

BACKGROUND: Allergic bronchopulmonary aspergillosis (ABPA) is a major complication in cystic fibrosis (CF) patients. Risk factors for ABPA and clinical deterioration in CF patients, negative for Pseudomonas aeruginosa (Pa), were explored. METHODS: We performed a retrospective case-control study in 73 Pa-negative patients. Each patient was matched with 2 controls for age, gender, pancreas sufficiency, DeltaF508 mutation (homozygous or heterozygous), and Pa colonization. RESULTS: Median FEV1 at the year of diagnosis (index year) was significantly lower in patients with ABPA. The median of cumulative values of FEV1 and FVC before the index year was not significantly different. After the index year, the median of cumulative data for FEV1 and FVC was significantly lower; there were significantly more hospitalization days and more IV antibiotic days compared to controls. Comparing pre- and post-index year data in patients with ABPA, significantly more hospitalization days and more IV antibiotic days were observed after the index year. During the period preceding the index year, significantly more ABPA patients were treated with rhDNase and inhaled corticosteroids. CONCLUSIONS: Bronchial damage cannot be considered as a facilitating factor for ABPA. ABPA causes a significant increase in bronchial damage. In patients with ABPA, further bronchial damage can be controlled by an increase in hospitalization days and use of IV antibiotics. rhDNase and inhaled corticosteroids were associated with the development of ABPA.

Exercise performance and quality of life in children with cystic fibrosis and mildly impaired lung function: relation with antibiotic treatments and hospitalization.

This study evaluates the impact of antibiotic treatments and hospitalization on exercise performance and health-related quality of life (QOL) in children with mild cystic fibrosis (CF) lung disease. Forty-seven children between 7 and 17 years with mild CF underwent a maximal exercise test including spiro-ergometry and filled out a QOL-questionnaire (PedsQL™). Amount of antibiotic treatments (AB) and hospitalization days in the last 3 years were reviewed. FEV1% was mildly decreased (91.7 ± 17.9 L/min, p = 0.02). Maximal oxygen consumption (VO2max), test duration and anaerobic threshold were lower compared to a control population (VO2max% 94 ± 15 vs 103 ± 13, p = 0.009). FEV1% correlated with AB and hospitalization episodes in the last year and 3 years before testing, VO2max% only correlated with AB in the last 3 years. Domains of school functioning and emotional functioning were low. Children with higher VO2max% and less AB in the last 3 years had better physical health. Physical health and school functioning were negatively correlated with hospitalization days in the last year. CONCLUSION: Patients with mild CF lung disease have good exercise performance although still lower than the normal population. VO2max% is affected by number of antibiotic treatments over a longer period. There is an impact of hospitalization days on quality of life. What is Known: • Children with CF have lower exercise performance; there is an association between hospitalization frequency and exercise performance • Quality of life is diminished in children with CF and influenced by respiratory infections What is New: • Even patients with mild CF lung disease have lower maximal exercise performance (VO 2 max) and a lower anaerobic threshold; VO 2 max is lower in children who had more antibiotic treatments in the last 3 years • School and emotional functioning are diminished in children with mild CF lung disease; hospitalization is negatively correlated with school functioning and physical functioning.

Epidemic Achromobacter xylosoxidans strain among Belgian cystic fibrosis patients and review of literature.

BACKGROUND: Achromobacter xylosoxidans is increasingly being recognized as an emerging pathogen in cystic fibrosis. Recent severe infections with A. xylosoxidans in some of our cystic fibrosis (CF) patients led to a re-evaluation of the epidemiology of CF-associated A. xylosoxidans infections in two Belgian reference centres (Antwerp and Ghent). Several of these patients also stayed at the Rehabilitation Centre De Haan (RHC). In total, 59 A. xylosoxidans isolates from 31 patients (including 26 CF patients), collected between 2001 and 2014, were studied. We evaluated Matrix Assisted Laser Desorption Ionisation -Time of Flight mass spectrometry (MALDI-TOF) as an alternative for McRAPD typing. RESULTS: Both typing approaches established the presence of a major cluster, comprising isolates, all from 21 CF patients, including from two patients sampled when staying at the RHC a decade ago. This major cluster was the same as the cluster established already a decade ago at the RHC. A minor cluster consisted of 13 isolates from miscellaneous origin. A further seven isolates, including one from a non-CF patient who had stayed recently at the RHC, were singletons. CONCLUSIONS: Typing results of both methods were similar, indicating transmission of a single clone of A. xylosoxidans among several CF patients from at least two reference centres. Isolates of the same clone were already observed at the RHC, a decade ago. It is difficult to establish to what extent the RHC is the source of transmission, because the epidemic strain was already present when the first epidemiological study in the RHC was carried out. This study also documents the applicability of MALDI-TOF for typing of strains within the species A. xylosoxidans and the need to use the dynamic cutoff algorithm of the BioNumerics® software for correct clustering of the fingerprints.

Streptococcal pharyngitis in children: to treat or not to treat?

UNLABELLED: Controversy remains about the need for antibiotic therapy of group A streptococcal (GAS) pharyngitis in high-resource settings. Guidelines on the management of GAS pharyngitis differ considerably, especially in children. We performed a literature search on the diagnosis and treatment of GAS pharyngitis in children and compared different guidelines with current epidemiology and the available evidence on management. Some European guidelines only recommend antibiotic treatment in certain high-risk patients, while many other, including all American, still advise antimicrobial treatment for all children with GAS pharyngitis, given the severity and re-emerging incidence of complications. Empirical antimicrobial treatment in children with sore throat and a high clinical suspicion of GAS pharyngitis will still result in significant overtreatment of nonstreptococcal pharyngitis. This is costly and leads to emerging antibiotic resistance. Early differential diagnosis between viral and GAS pharyngitis, by means of a 'rapid antigen detection test' (RADT) and/or a throat culture, is therefore needed if 'pro treatment' guidelines are used. CONCLUSION: Large scale randomized controlled trials are necessary to assess the value of antibiotics for GAS pharyngitis in high-resource countries, in order to achieve uniform and evidence-based guidelines. The severity and the possibly increasing incidence of complications in school-aged children suggests that testing and treating proven GAS pharyngitis can still be beneficial.

The use of information technology to improve interdisciplinary communication during infectious diseases ward rounds on the paediatric intensive care unit.

Prospective audit with feedback during infectious diseases ward rounds (IDWR) is a common antimicrobial stewardship (AMS) practice on the Paediatric Intensive Care Unit (PICU). These interdisciplinary meetings rely on the quality of handover, with high risk of omission of information. We developed an electronic platform integrating infection-related patient data (COSARAPed). In the mixed PICU of a Belgian tertiary hospital we conducted an observational prospective cohort study comparing patient handovers during IDWRs using the COSARAPed-platform to those with access only to conventional resources. The quality of handover was investigated directly by assessment if the narrative was in accordance with Situation-Background-Assessment-Recommendation principles and if adequate demonstration of diagnostic information occurred, and also indirectly by registration if this was only achieved after intervention by the non-presenting AMS team members. We also recorded all AMS-recommendations. During a 6-month study period, 24 IDWRs and 82 patient presentations were assessed. We could only find a statistically significant advantage in favor of COSARAPed by indirect evaluation. We registered 92 AMS-recommendations, mainly resulting in reduced antibiotic pressure. We concluded that the IDWR is an appropriate platform for AMS on the PICU and that the utilisation of COSARAPed may enhance the quality of patient handover.

Spleen function is reduced in individuals with NR5A1 variants with or without a difference of sex development: a cross-sectional study.

OBJECTIVE: NR5A1 is a key regulator of sex differentiation and has been implicated in spleen development through transcription activation of TLX1. Concerns exist about hypo- or asplenism in individuals who have a difference of sex development (DSD) due to an NR5A1 disease-causing variant. We aimed to assess spleen anatomy and function in a clinical cohort of such individuals and in their asymptomatic family member carriers. DESIGN: Cross-sectional assessment in 22 patients with a DSD or primary ovarian insufficiency and 5 asymptomatic carriers from 18 families, harboring 14 different NR5A1 variants. METHODS: Spleen anatomy was assessed by ultrasound, spleen function by peripheral blood cell count, white blood cell differentiation, percentage of nonswitched memory B cells, specific pneumococcal antibody response, % pitted red blood cells, and Howell-Jolly bodies. RESULTS: Patients and asymptomatic heterozygous individuals had significantly decreased nonswitched memory B cells compared to healthy controls, but higher than asplenic patients. Thrombocytosis and spleen hypoplasia were present in 50% of heterozygous individuals. Four out of 5 individuals homozygous for the previously described p.(Arg103Gln) variant had asplenia. CONCLUSIONS: Individuals harboring a heterozygous NR5A1 variant that may cause DSD have a considerable risk for functional hyposplenism, irrespective of their gonadal phenotype. Splenic function should be assessed in these individuals, and if affected or unknown, prophylaxis is recommended to prevent invasive encapsulated bacterial infections. The splenic phenotype associated with NR5A1 variants is more severe in homozygous individuals and is, at least for the p.(Arg103Gln) variant, associated with asplenism.

SARS-CoV-2 Infection in Children Less Than Forty Days Hospitalized in Belgium Between 2020 and 2022.

Our study aimed to assess the severity of severe acute respiratory syndrome coronavirus 2 infection in hospitalized infants under 40 days old, across 21 Belgian hospitals between 2020 and 2022. Of the 365 infants studied, 14.2% needed respiratory support. The median hospital stay was 3 days (interquartile range, 2-4), and there were no deaths. Infection severity was similar during the Omicron and Alpha/Delta periods.

Complete factor I deficiency due to dysfunctional factor I with recurrent aseptic meningo-encephalitis.

PURPOSE: Complement regulators control the activated complement system. Defects in this homeostasis can result in tissue damage and autoimmune diseases with a heterogeneity in clinical presentation. Complement factor I (FI), a serine protease, is an important regulator of alternative pathway activation. We report a diagnostic work-up of a patient with relapsing inflammatory mediated meningo-encephalitis. Our work-up revealed a rare genetic factor I (FI) deficiency. So far, all cases of reported complete factor I deficiency have absent serum levels of FI. We present here a unique case of a complete factor I deficiency based on a functional FI defect. METHODS: Complement assays and measurement of FI activity were performed in the patient, her family, factor H-deficient patients, a patient with C3-nephritic factor and 11 healthy controls. Genetic sequencing of the FI coding regions in the patient and her parents was performed. RESULTS: The patient had absent alternative pathway activity with low levels of C3 and normal serum level of FI. The patient's plasma FI did not degrade C3b, with normalisation of C3b degradation after adding purified FI. Mutation analysis of the complement factor I gene revealed two heterozygous mutations (I322T and D506V). CONCLUSION: To our knowledge, this paper describes a complete FI deficiency caused by a defect of FI activity for the first time. Normal FI concentration does not exclude a complete FI defect, additional functional analysis of FI is required in any patient with a defect of complement activation. Recurrent aseptic meningo-encephalitis is a rare clinical presentation of complete FI deficiency.

Sampling and decontamination method for culture of nontuberculous mycobacteria in respiratory samples of cystic fibrosis patients.

We confirmed that chlorhexidine decontamination yielded more nontuberculous mycobacteria than did the N-acetyl-l-cysteine-NaOH-oxalic acid procedure from respiratory samples of cystic fibrosis patients on solid cultures. However, this improved recovery is mostly balanced if the latter is combined with liquid culture. Furthermore, none of the 145 cough swabs, used to sample young children, cultured positive, suggesting that swabs are low-quality samples.

Anterior and posterior tracheopexy for severe tracheomalacia.

Objectives: Congenital tracheomalacia can be the cause of respiratory failure in young children. Although the indication for surgical treatment has already been discussed vigorously, no clear guidelines about the modality are available. Methods: Through a sternotomy approach, a combination of posterior pexy and anterior tracheopexy using a tailored ringed polytetrafluoroethylene prosthesis is performed. Patient demographic characteristics, as well as operative details and postoperative outcomes, are included in the analysis. Results: Between 2018 and 2022, 9 children underwent the operation under review. All patients showed severe clinical symptoms of tracheomalacia, which was confirmed on bronchoscopy. The median age was 9 months. There was no operative mortality. Eight patients could be weaned from the ventilator. One patient died because of interstitial lung disease with bronchomalacia and concomitant severe cardiac disease. The longest follow-up now is 4 years, and shows overall excellent clinical results, without any reintervention. Conclusions: Surgical treatment of tracheomalacia through a combination of posterior and anterior pexy is feasible, with acceptable short- and midterm results.

Comparison of SARS-CoV-2 seroconversion in children with chronic diseases with healthy children and adults during the first waves of the COVID-19 pandemic.

Background: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is clinically diverse, and children have a low risk of developing severe coronavirus disease 2019 (COVID-19). However, children with chronic diseases have a potentially increased risk. Methods: We performed a prospective surveillance study with longitudinal serum SARS-CoV-2 anti-nucleocapsid antibody quantification and questionnaires in pediatric tertiary care patients during the first waves of the COVID-19 pandemic (November 2020-September 2021). The results were compared with those of healthy children and adults from the same geographic area. Results: We obtained 525 samples from 362 patients (M/F ratio of 1.3:1; median age of 11.1 years) comprising children with immune-suppressive or immune-modulating drugs (32.9%), inborn errors of immunity (23.5%), type 1 diabetes mellitus (15.2%), and rheumatic diseases (11.9%). A total of 51 (9.7%) samples were seropositive among 37/351 children (10.5%). Seropositivity increased from 5.8% in November-December 2020 to 21.6% in July-September 2021. Compared with adults, a longitudinal analysis revealed reduced seroprevalence but similar kinetics as in children from the same country. Demographic or social variables and disease characteristics did not correlate with seropositivity. Being obese and household contact with COVID-19-infected individuals significantly increased the odds of infection. The majority of seropositive patients had mild symptoms (21/37). One-third were asymptomatic and/or unaware of having COVID-19 (10/37). Four patients (4/37) needed hospitalization, with good clinical outcomes. Conclusions: Although harboring a chronic disease, we observed a low SARS-CoV-2 incidence in a cohort of pediatric tertiary care patients, comparable with healthy children during the first year of the pandemic. Infection was mostly associated with mild symptoms.

Sensitivity and specificity of 14 SARS-CoV-2 serological assays and their diagnostic potential in RT-PCR negative COVID-19 infections.

BACKGROUND: Molecular detection of SARS-CoV-2 in respiratory samples is the gold standard for COVID-19 diagnosis but it has a long turnaround time and struggles to detect low viral loads. Serology could help to diagnose suspected cases which lack molecular confirmation. Two case reports are presented as illustration. OBJECTIVES: The aim of this study was to evaluate the performance of several commercial assays for COVID-19 serology. We illustrated the added value of COVID-19 serology testing in suspect COVID-19 cases with negative molecular test. STUDY DESIGN: Twenty-three sera from 7 patients with a confirmed molecular diagnosis of SARS-CoV-2 were tested using 14 commercial assays. Additionally, 10 pre-pandemic sera and 9 potentially cross-reactive sera were selected. We calculated sensitivity and specificity. Furthermore, we discuss the diagnostic relevance of COVID-19 serology in a retrospective cohort of 145 COVID-19 cases in which repetitive molecular and serological SARS-CoV-2 tests were applied. RESULTS: The interpretation of the pooled sensitivity of IgM/A and IgG resulted in the highest values (range 14-71% on day 2-7; 88-94% on day 8-18). Overall, the specificity of the assays was high (range 79-100%). Among 145 retrospective cases, 3 cases (2%) remained negative after sequential molecular testing but positive on final SARS-CoV-2 serology. CONCLUSION: Sensitivity of COVID-19 serological diagnosis was variable but consistently increased at >7 days after symptom onset. Specificity was high. Our data suggest that serology can complement molecular testing for diagnosis of COVID-19, especially for patients presenting the 2nd week after symptom onset or later.

TIM3+ TRBV11-2 T cells and IFNγ signature in patrolling monocytes and CD16+ NK cells delineate MIS-C.

In rare instances, pediatric SARS-CoV-2 infection results in a novel immunodysregulation syndrome termed multisystem inflammatory syndrome in children (MIS-C). We compared MIS-C immunopathology with severe COVID-19 in adults. MIS-C does not result in pneumocyte damage but is associated with vascular endotheliitis and gastrointestinal epithelial injury. In MIS-C, the cytokine release syndrome is characterized by IFNγ and not type I interferon. Persistence of patrolling monocytes differentiates MIS-C from severe COVID-19, which is dominated by HLA-DRlo classical monocytes. IFNγ levels correlate with granzyme B production in CD16+ NK cells and TIM3 expression on CD38+/HLA-DR+ T cells. Single-cell TCR profiling reveals a skewed TCRß repertoire enriched for TRBV11-2 and a superantigenic signature in TIM3+/CD38+/HLA-DR+ T cells. Using NicheNet, we confirm IFNγ as a central cytokine in the communication between TIM3+/CD38+/HLA-DR+ T cells, CD16+ NK cells, and patrolling monocytes. Normalization of IFNγ, loss of TIM3, quiescence of CD16+ NK cells, and contraction of patrolling monocytes upon clinical resolution highlight their potential role in MIS-C immunopathogenesis.