Analysis of Plasmablasts From Children With Kawasaki Disease Reveals Evidence of a Convergent Antibody Response to a Specific Protein Epitope.

BACKGROUND: Kawasaki disease (KD) is a febrile illness of young childhood that can result in coronary artery aneurysms and death. Coronavirus disease 2019 (COVID-19) mitigation strategies resulted in a marked decrease in KD cases worldwide, supporting a transmissible respiratory agent as the cause. We previously reported a peptide epitope recognized by monoclonal antibodies (MAbs) derived from clonally expanded peripheral blood plasmablasts from 3 of 11 KD children, suggesting a common disease trigger in a subset of patients with KD. METHODS: We performed amino acid substitution scans to develop modified peptides with improved recognition by KD MAbs. We prepared additional MAbs from KD peripheral blood plasmablasts and assessed MAb characteristics that were associated with binding to the modified peptides. RESULTS: We report a modified peptide epitope that is recognized by 20 MAbs from 11 of 12 KD patients. These MAbs predominantly use heavy chain VH3-74; two-thirds of VH3-74 plasmablasts from these patients recognize the epitope. The MAbs were nonidentical between patients but share a common complementarity-determining region 3 (CDR3) motif. CONCLUSIONS: These results demonstrate a convergent VH3-74 plasmablast response to a specific protein antigen in children with KD, supporting one predominant causative agent in the etiopathogenesis of the illness.

A Protein Epitope Targeted by the Antibody Response to Kawasaki Disease.

BACKGROUND: Kawasaki disease (KD) is the leading cause of childhood acquired heart disease in developed nations and can result in coronary artery aneurysms and death. Clinical and epidemiologic features implicate an infectious cause but specific antigenic targets of the disease are unknown. Peripheral blood plasmablasts are normally highly clonally diverse but the antibodies they encode are approximately 70% antigen-specific 1-2 weeks after infection. METHODS: We isolated single peripheral blood plasmablasts from children with KD 1-3 weeks after onset and prepared 60 monoclonal antibodies (mAbs). We used the mAbs to identify their target antigens and assessed serologic response among KD patients and controls to specific antigen. RESULTS: Thirty-two mAbs from 9 of 11 patients recognize antigen within intracytoplasmic inclusion bodies in ciliated bronchial epithelial cells of fatal cases. Five of these mAbs, from 3 patients with coronary aneurysms, recognize a specific peptide, which blocks binding to inclusion bodies. Sera from 5/8 KD patients day ≥ 8 after illness onset, compared with 0/17 infant controls (P < .01), recognized the KD peptide antigen. CONCLUSIONS: These results identify a protein epitope targeted by the antibody response to KD and provide a means to elucidate the pathogenesis of this important worldwide pediatric problem.

Clostridium difficile Whole Genome Sequencing Reveals Limited Transmission Among Symptomatic Children: A Single-Center Analysis.

Background: Although pediatric Clostridium difficile infections (CDIs) are increasing, C. difficile transmission patterns among children are poorly understood. Methods: We performed whole genome sequencing (WGS) on C. difficile isolates collected from children diagnosed with CDI between December 2012 and December 2013 at a single academic medical center. Genome sequences of isolates from CDIs diagnosed ≥8 weeks after study initiation were compared to all study isolate genome sequences. Among patients with isogenic isolates (≤2-3 core genome single nucleotide variants [SNVs] identified by pairwise SNV analyses), common inpatient and/or outpatient healthcare exposures were investigated. Results: Among 131 CDIs in 107 children, WGS identified 104 genetically distinct isolates. Of 84 incident CDIs occurring ≥8 weeks after study initiation, only 10 (11.9%) were caused by a strain isogenic to another cohort CDI isolate (putative transmission events). Proportions of each CDI class putatively associated with transmission were hospital-onset healthcare facility-associated (HCFA), 2/16 (12.5%); community-onset HCFA, 1/17 (5.9%); indeterminate, 1/11 (9.1%); community-associated (CA), 5/40 (12.5%); and recurrent, 1/21 (4.8%). Transmission events among CA and HCFA CDIs were similarly infrequent (5/40 [12.5%] vs 3/33 [9.1%]; P = .64). Shared healthcare facility exposures were only identified among 7/10 putative transmission events. Potential community transmission (same postal code) was not identified. Conclusions: WGS identified a highly diverse group of C. difficile isolates among children with CDI, including those with HCFA CDI. Clostridium difficile transmission among symptomatic children was very uncommon. Among putatively transmitted cases, investigation of shared healthcare exposures often did not identify a potential transmission source.

Revision of the Jones Criteria for the diagnosis of acute rheumatic fever in the era of Doppler echocardiography: a scientific statement from the American Heart Association.

BACKGROUND: Acute rheumatic fever remains a serious healthcare concern for the majority of the world's population despite its decline in incidence in Europe and North America. The goal of this statement was to review the historic Jones criteria used to diagnose acute rheumatic fever in the context of the current epidemiology of the disease and to update those criteria to also take into account recent evidence supporting the use of Doppler echocardiography in the diagnosis of carditis as a major manifestation of acute rheumatic fever. METHODS AND RESULTS: To achieve this goal, the American Heart Association's Council on Cardiovascular Disease in the Young and its Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee organized a writing group to comprehensively review and evaluate the impact of population-specific differences in acute rheumatic fever presentation and changes in presentation that can result from the now worldwide availability of nonsteroidal anti-inflammatory drugs. In addition, a methodological assessment of the numerous published studies that support the use of Doppler echocardiography as a means to diagnose cardiac involvement in acute rheumatic fever, even when overt clinical findings are not apparent, was undertaken to determine the evidence basis for defining subclinical carditis and including it as a major criterion of the Jones criteria. This effort has resulted in the first substantial revision to the Jones criteria by the American Heart Association since 1992 and the first application of the Classification of Recommendations and Levels of Evidence categories developed by the American College of Cardiology/American Heart Association to the Jones criteria. CONCLUSIONS: This revision of the Jones criteria now brings them into closer alignment with other international guidelines for the diagnosis of acute rheumatic fever by defining high-risk populations, recognizing variability in clinical presentation in these high-risk populations, and including Doppler echocardiography as a tool to diagnose cardiac involvement.

Comparison of illumigene Group A Streptococcus Assay with Culture of Throat Swabs from Children with Sore Throats in the New Zealand School-Based Rheumatic Fever Prevention Program.

Group A streptococcal (GAS) pharyngitis is a particularly important condition in areas of New Zealand where the incidence of acute rheumatic fever remains unacceptably high. Prompt diagnosis and treatment of GAS pharyngitis are cornerstones of the Rheumatic Fever Prevention Programme, but these are hindered by the turnaround time of culture. Tests with excellent performance and rapid turnaround times are needed. For this study, throat swabs (Copan ESwabs) were collected from schoolchildren self-identifying with a sore throat. Samples were tested by routine culture and the illumigene GAS assay using loop-mediated isothermal amplification. Discrepant results were resolved by retesting of the same specimen by an alternative molecular assay. Seven hundred fifty-seven throat swab specimens were tested by both methods. The performance characteristics of the illumigene assay using culture on blood agar as the "gold standard" and following discrepancy analysis were as follows: sensitivity, 82% and 87%, respectively; specificity, 93% and 98%, respectively; positive predictive value, 61% and 88%, respectively; and negative predictive value, 97% and 97%, respectively. In our unique setting of a school-based throat swabbing program, the illumigene assay did not perform quite as well as described in previous reports. Despite this, its improved sensitivity and rapid turnaround time compared with those of culture are appealing.

Kawasaki Disease and Exposure to Fine Particulate Air Pollution.

OBJECTIVE: To analyze associations of short-term exposure to fine particulate matter (diameter ≤ 2.5 µm [PM2.5]), a measurable component of urban pollution, with the event date of fever onset for patients with Kawasaki disease (KD) residing in 7 metropolitan regions. STUDY DESIGN: A case-crossover study design was used. Time trends, seasonality, month, and weekday were controlled for by matching. We assembled PM2.5 exposure measurements from urban monitors and imputed PM2.5 to provide day-to-day temporal variability and resolution for time series indexes of exposures. Selected exposure windows (to 14 days) of PM2.5 were examined. RESULTS: A total of 3009 KD events were included for which the subject resided within a study metropolitan area and the event date occurred during years with available PM2.5. The estimated ORs (with 95% CIs) of an event of KD associated with a 10 µg/m(3) PM2.5 lagged moving average concentration of lagged exposure period (ie, concurrent, preceding day[s]) revealed no evidence of a consistent, statistically significant, positive association between elevated PM2.5 exposure and increased risk of KD. Extended analysis with stratification by city, sex, age, ethnic origin, incomplete or complete clinical manifestations, the presence of coronary aneurysm, and intravenous immunoglobulin resistance did not provide evidence of a consistent, statistically significant, positive association between elevated exposure to PM2.5 and increased risk of KD for any of the strata studied. CONCLUSIONS: This multicity study failed to establish a risk of the event of KD with short-term fine particulate exposure. Our negative findings add to the growing field of environmental epidemiology research of KD.

Notes from the Field: Group A Streptococcal Pharyngitis Misdiagnoses at a Rural Urgent-Care Clinic--Wyoming, March 2015.

Group A Streptococcus (GAS) is the most common bacterial cause of pharyngitis, implicated in 20%-30% of pediatric and 5%-15% of adult health care visits for sore throat (1). Along with the sudden onset of throat pain, GAS pharyngitis symptoms include fever, headache, and bilateral tender cervical lymphadenopathy (1,2). Accurate diagnosis and management of GAS pharyngitis is critical for limiting antibiotic overuse and preventing rheumatic fever (2), but distinguishing between GAS and viral pharyngitis clinically is challenging (1). Guidelines for diagnosis and management of GAS pharyngitis have been published by the Infectious Diseases Society of America (IDSA)* (1). IDSA recommends that patients with sore throat be tested for GAS to distinguish between GAS and viral pharyngitis; however, IDSA emphasizes the use of selective testing based on clinical symptoms and signs to avoid identifying GAS carriers rather than acute GAS infections (1). Therefore, testing for GAS usually is not recommended for the following: patients with sore throat and accompanying symptoms (e.g., cough, rhinorrhea) that strongly suggest a viral etiology; children aged <3 years, because acute rheumatic fever is extremely rare in this age group; and asymptomatic household contacts of patients with GAS pharyngitis (1). IDSA recommends penicillin or amoxicillin as the treatment of choice based on effectiveness and narrow spectrum of activity. To date, penicillin-resistant GAS has never been documented (1).

The transcriptional profile of coronary arteritis in Kawasaki disease.

BACKGROUND: Kawasaki Disease (KD) can cause potentially life-threatening coronary arteritis in young children, and has a likely infectious etiology. Transcriptome profiling is a powerful approach to investigate gene expression in diseased tissues. RNA sequencing of KD coronary arteries could elucidate the etiology and the host response, with the potential to improve KD diagnosis and/or treatment. METHODS: Deep RNA sequencing was performed on KD (n = 8) and childhood control (n = 7) coronary artery tissues, revealing 1074 differentially expressed mRNAs. Non-human RNA sequences were subjected to a microbial discovery bioinformatics platform, and microbial sequences were analyzed by Metastats for association with KD. RESULTS: T lymphocyte activation, antigen presentation, immunoglobulin production, and type I interferon response were significantly upregulated in KD arteritis, while the tumor necrosis factor α pathway was not differentially expressed. Transcripts from known infectious agents were not specifically associated with KD coronary arteritis. CONCLUSIONS: The immune transcriptional profile in KD coronary artery tissues has features of an antiviral immune response such as activated cytotoxic T lymphocyte and type I interferon-induced gene upregulation. These results provide new insights into the pathogenesis of KD arteritis that can guide selection of new immunomodulatory therapies for high-risk KD patients, and provide direction for future etiologic studies.

Risk Factors for Recurrent Clostridium difficile Infection in Children: A Nested Case-Control Study.

OBJECTIVE: To identify risk factors for recurrent Clostridium difficile infection (RCDI) in children. STUDY DESIGN: A nested case-control study was performed to identify RCDI risk factors using a pediatric cohort of inpatients and outpatients diagnosed with Clostridium difficile infection by tcdB polymerase chain reaction (PCR) at an academic children's hospital between December 9, 2012, and June 30, 2014. Strict inclusion criteria were adopted to limit selection bias related to inappropriate inclusion of patients with probable C difficile colonization. RESULTS: Thirty children with RCDI were compared with 94 children with non-RCDI. Statistically significant associations were identified between RCDI and malignancy (OR 2.8, 95% CI 1.0-7.4, P = .044), tracheostomy tube dependence (OR 5.2, 95% CI 1.1-24.7, P = .037), and tcdB PCR cycle threshold (OR 0.87, 95% CI 0.78-0.97, P = .01) using multivariable logistic regression modeling. The receiver operator characteristic curve for PCR cycle threshold as a predictor of RCDI demonstrated area under the curve = 0.67. The highest predictive rate (75%) for RCDI was demonstrated at cycle threshold cutpoint ≤ 20. The difference between sensitivity (64%) and specificity (68%) was minimized at cycle threshold cutpoint ≤ 23. Compared with controls with non-RCDI, children excluded because of probable C difficile colonization had a similar cycle threshold value (27.5 vs 27.2, P = .77). CONCLUSIONS: Malignancy and tracheostomy tube dependence were identified as RCDI risk factors. Although RCDI was associated with positivity at a lower tcdB PCR cycle threshold, the clinical utility of cycle threshold as a tool to predict recurrence was limited. Better methods to predict RCDI are needed to prioritize pediatric populations to target for RCDI prevention efforts.

Kawasaki disease: a comprehensive review of treatment options.

WHAT IS KNOWN AND OBJECTIVE: Kawasaki disease (KD) is an acute self-limiting systemic vasculitis with specific predilection for the coronary arteries that affects previously healthy young infants and children. It is the leading cause of childhood-acquired heart disease in the developed world. Although the stimulus for the cascade of inflammation in KD is unknown, prompt treatment within 10 days of symptom onset has been shown to improve clinical outcomes and reduce the risk of coronary artery complications. Standard initial therapy is intravenous immunoglobulin (IVIG) and aspirin. Non-responders to initial therapy remain a challenge. This present review summarizes the treatment options for initial and refractory KD, including the role of steroids and other immunosuppressive therapies. METHODS: Literature search using PubMed database to identify pharmacologic studies in KD using the terms Kawasaki disease, intravenous immunoglobulin, refractory, corticosteroids, infliximab, cyclosporine, methotrexate, high risk from January 1988-May 2015 was performed. Bibliographies of selected references were also evaluated for relevant articles. Results were limited to those published in English. All articles identified from the PubMed searches were evaluated. RESULTS AND DISCUSSION: Initial IVIG therapy results in rapid resolution of clinical symptoms in 80-90% of patients and has been shown to reduce the risk of coronary disease. Although concomitant aspirin remains the standard of care for the initial management of KD, the evidence to support its efficacy in improving coronary artery outcomes are lacking. Initial therapy with corticosteroids in addition to intravenous immunoglobulin and aspirin improves outcomes in patients in Japan. However, identifying patients at high risk who may benefit from additional corticosteroids in heterogeneous populations has been challenging. Therapeutic options for non-responders to initial therapy are also challenging given the paucity of data. Patients who fail to respond to the first dose of IVIG will most often receive a second dose. Patients who fail to respond to two doses of IVIG present a unique challenge as the appropriate treatment remains uncertain. Although their effectiveness remains unproven, treatment with infliximab, cyclosporine or methotrexate may be considered in those patients who fail multiple doses of IVIG and steroids. WHAT IS NEW AND CONCLUSION: The role of steroids in high-risk non-Japanese patients is unclear, with the biggest challenge being early identification of patients at high risk of developing adverse coronary artery outcomes. Limited data evaluating other immunosuppressive agents are available and should be reserved for patients failing two doses of IVIG. Although recent advances in research have broadened our understanding of the epidemiology, genetic susceptibility and pathogenesis of KD, the aetiology of KD remains unclear. Ongoing research will help determine more precise pathogenesis and may assist in developing a diagnostic test as well as identifying new targets for more precise treatment interventions.

Group A Streptococcus pharyngitis in Children: New Perspectives on Rapid Diagnostic Testing and Antimicrobial Stewardship.

The most common cause of bacterial pharyngitis is Group A Streptococcus (GAS). Accurate diagnosis of GAS pharyngitis is crucial to identify children who would benefit from antibiotic treatment. Rapid diagnosis has the potential to reduce antibiotic overuse. Current national guidelines differ in their recommendations for GAS testing. While rapid antigen detection tests (RADTs) are widely used, their sensitivity is considered too low for stand-alone testing by several expert bodies. Newer molecular tests using nucleic acid amplification show higher accuracy and fast results, but their cost, complexity, and very high sensitivity may limit widespread adoption. This review provides up-to-date evidence regarding rapid diagnostic testing and antimicrobial stewardship in children with sore throat. We discuss discrepancies across GAS testing guidelines at the international level, patient selection for testing for GAS, rapid test accuracy, and the potential role of rapid GAS tests to promote antibiotic stewardship, with emphasis on emerging rapid molecular tests.

Coronary Artery Outcomes in Kawasaki Disease by Treatment Day Within 10 Days of Fever Onset.

Background: Kawasaki disease (KD) is an acute febrile illness of childhood that can lead to coronary artery aneurysms (CAAs) and myocardial infarction. Intravenous immunoglobulin reduces the prevalence of CAA when given to patients with KD within 10 days of fever onset. Children with KD may undergo evaluation for other diagnoses before treatment, particularly those with incomplete KD criteria. If KD outcomes are improved with early treatment, a delay in treatment while evaluating for other causes might place these patients at risk. Methods: We performed a retrospective cohort study of children treated for KD within the first 10 days of illness at our KD center from 2014 to 2021 to determine the prevalence of CAA by day of treatment. Results: A total of 290 patients met the study criteria. No statistically significant difference was found in the odds of developing a maximum z score ≥2.5 for each day of delayed treatment within 10 days of fever onset (adjusted odds ratio, 0.87; 95% CI, .72-1.05; P = .13). Subgroup analyses by age, sex, and year of treatment did not reveal a significant association between treatment day and maximum z score ≥2.5, although the number of patients <6 months of age was small. Conclusions: Our study supports current recommendations. We found similar odds of developing adverse coronary outcomes regardless of treatment day within 10 days from fever onset.

Detection of Streptococcus pyogenes by use of Illumigene group A Streptococcus assay.

The performance of the Illumigene group A Streptococcus assay was evaluated by comparing it to culture using 437 consecutive throat swabs. The Illumigene assay was also directly compared to PCR with 161 samples. This Illumigene assay is rapid and easy to perform. The assay also has high sensitivity (100%) compared to culture or PCR and high specificity (99.2%) compared to PCR. A total of 8.8% of the isolates were erythromycin resistant, and 6.9% were clindamycin resistant.

Integrins α4 and αM, collagen1A1, and matrix metalloproteinase 7 are upregulated in acute Kawasaki disease vasculopathy.

BACKGROUND: Kawasaki disease (KD) can result in fatal coronary artery (CA) aneurysms, especially if left untreated. Our recent studies of its vascular pathology revealed subacute/chronic vasculitis that begins early in the illness with the proliferation of smooth muscle cell-derived myofibroblasts in a complex extracellular matrix (ECM). We hypothesized that a dysregulation of specific ECM and adhesion molecules occurs in KD CAs. METHODS: Gene expression profiling for ECM and adhesion molecules was performed on six acute KD and eight control CAs using a targeted real-time PCR array approach. RESULTS: Integrins α4 and αM (ITGA4, ITGAM), collagen type I, α1 (COL1A1), and matrix metalloproteinase 7 (MMP7) were significantly upregulated in KD CAs as compared with controls. Immunohistochemistry with anti-ITGAM antibodies revealed expression on inflammatory cells within the CA wall in patients with KD but not in controls. CONCLUSION: Integrins ITGA4 and ITGAM are upregulated in KD vasculopathy, probably promoting inflammatory recruitment that stimulates smooth muscle cell transition to myofibroblasts and their proliferation. MMP7 probably enhances myofibroblast proliferation and luminal lesion expansion, and overexpression of COL1A1 may lead to CA stenosis. Identification of the molecular pathogenesis of KD vasculopathy may lead to the development of circulating biomarkers and to directed therapeutic interventions.

Kawasaki disease: part I. Diagnosis, clinical features, and pathogenesis.

Kawasaki disease, or mucocutaneous lymph node syndrome, most commonly affects children between 6 months and 5 years of age. Approximately 90% of patients have mucocutaneous manifestations. This article will focus on the epidemiology of Kawasaki disease in the United States as it relates to other countries, the diagnosis of Kawasaki disease, its clinical course, and the currently accepted theories of pathogenesis. A particular focus is given to the various dermatologic manifestations that may occur.