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During the coronavirus disease 2019 (COVID-19) pandemic, a novel multisystem inflammatory syndrome in children (MIS-C) has been reported worldwide since the first cases were reported in Europe in April 2020. MIS-C is temporally associated with severe acute respiratory syndrome coronavirus 2 infection and shows Kawasaki disease (KD)-like features. The epidemiological and clinical characteristics in COVID-19, KD, and MIS-C differ, but severe cases of each disease share similar clinical and laboratory findings such as a protracted clinical course, multiorgan involvement, and similar activated biomarkers. These findings suggest that a common control system of the host may act against severe disease insult. To solve the enigmas, we proposed the protein-homeostasis-system hypothesis in that every disease involves etiological substances and the host’s immune system controls them by their size and biochemical properties. Also, it is proposed that the etiological agents of KD and MIS-C might be certain strains in the microbiota of human species and etiological substances in severe COVID-19, KD, and MIS-C originate from pathogen-infected cells. Since disease severity depends on the amounts of inflammation-inducing substances and corresponding immune activation in the early stage of the disease, an early proper dose of corticosteroids and/or intravenous immunoglobulin (IVIG) may help reduce morbidity and possibly mortality among patients with these diseases. Corticosteroids are low cost and an analogue of host-origin cortisol among immune modulators. This study’s findings will help clinicians treating severe COVID-19, KD, and MIS-C, especially in developing countries, where IVIG and biologics supplies are insufficient.

Intravenous immunoglobulin (IVIG) resistance in patients with Kawasaki disease (KD) is defined as persistent or recrudescent fever ≥36 hours after IVIG infusion. We have experienced an increase in IVIG resistance in patients with KD since the substitution of 10% IVIG for 5% IVIG. This study aimed to determine the independent association between increased IVIG resistance and 10% IVIG therapy.Medical records of pediatric patients with KD were retrospectively reviewed. Clinical and laboratory characteristics were compared between patients receiving 5% IVIG therapy and those receiving 10% IVIG therapy. Between IVIG-responsive and IVIG-resistant patients, a multivariate analysis was performed to determine the independent factors for IVIG resistance.A total of 119 patients were included in this study: 81 (68.1%) and 38 (31.9%) patients received 5% and 10% IVIG therapy, respectively. IVIG resistance was identified in 34 (28.6%) patients: 44.7% of patients receiving 10% IVIG therapy and 21.0% of patients receiving 5% IVIG therapy (p = 0.008). The clinical manifestations and outcomes were comparable between patients who received 5% IVIG therapy and those who received 10% IVIG therapy. IVIG resistance was significantly associated with fewer fever days at IVIG administration (p = 0.032), a higher percentage of neutrophils (p = 0.013), and 10% IVIG treatment (p = 0.004) in the multivariate analysis.10% IVIG therapy was significantly associated with increased reporting of IVIG resistance. However, the increase in patients with fever patterns consistent with IVIG resistance seemed to represent adverse febrile reactions resulting from using high-concentration IVIG rather than increased severity of KD.

Background: Understanding the epidemiology and prevalence of febrile urinary tract infection (fUTI) in children is important for risk stratification and selecting appropriate urine sample collection candidates to aid in its diagnosis and treatment.Purpose: This study aimed to analyze the epidemiology, etiology, and changes in antibiotic susceptibility patterns of the first fUTI in children.Methods: This retrospective observational cohort study included children younger than 19 years of age who were diagnosed and treated for their first fUTI in 2006–2016. Electronic medical records were analyzed and radiologic images were evaluated.Results: A total of 359 patients (median age, 5.1 months; interquartile range, 3.0–10.5 months) fit the inclusion criteria; of them, 78.0% (n=280) were younger than 12 months old. The male to female ratio was 5.3:1 for patients aged 0–2 months, 2.1:1 for those 3–5 months, and 1.6:1 for those 6–11 months. Beyond 12 months of age, there was a female predominance. Escherichia coli was the leading cause (83.8%), followed by Enterococcus species (6.7%), and Klebsiella pneumoniae (3.6%). Significant yearly increases in the proportions of multidrug-resistant strains (PPP=0.03).Conclusion: fUTI was most prevalent in children younger than 12 months of age and showed a female predominance in patients older than 12 months of age. The proportion of ESBL producers causing fUTI is increasing. Carbapenems, rather than noncarbapenems, should be considered for treating fUTI caused by ESBL-producing enteric gram-negative rods to reduce short-term recurrence rates in children with VUR.

The novel coronavirus disease 2019 (COVID-19) is spreading globally. Although its etiologic agent is discovered as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), there are many unsolved issues in COVID-19 and other infectious diseases. The causes of different clinical phenotypes and incubation periods among individuals, species specificity, and cytokine storm with lymphopenia as well as the mechanism of damage to organ cells are unknown. It has been suggested that in viral pneumonia, virus itself is not a direct cause of acute lung injury; rather, aberrant immune reactions of the host to the insults from viral infection are responsible. According to its epidemiological and clinical characteristics, SARS-CoV-2 may be a virus with low virulence in nature that has adapted to the human species. Current immunological concepts have limited ability to explain such unsolved issues, and a presumed immunopathogenesis of COVID-19 is presented under the proteinhomeostasis-system hypothesis. Every disease, including COVID-19, has etiological substances controlled by the host immune system according to size and biochemical properties. Patients with severe pneumonia caused by SARS-CoV-2 show more severe hypercytokinemia with corresponding lymphocytopenia than patients with mild pneumonia; thus, early immunomodulator treatment, including corticosteroids, has been considered. However, current guidelines recommend their use only for patients with advanced pneumonia or acute respiratory distress syndrome. Since the immunopathogenesis of pneumonia may be the same for all patients regardless of age or severity and the critical immune-mediated lung injury may begin in the early stage of the disease, early immunomodulator treatment, including corticosteroids and intravenous immunoglobulin, can help reduce morbidity and possibly mortality rates of older patients with underlying conditions.

Background and Objectives: Considering developing resistance against neuraminidase inhibitors (NAIs) and their adverse reactions, restricted use of NAIs and use of alternative drugs should be considered for treating influenza. Although glucocorticoids (GCs) have been used for severe influenza, their effects on non-severe influenza have rarely been evaluated. This study aimed to evaluate the clinical responses to NAI therapy and GC therapy in pediatric patients with non-severe influenza. Materials and Methods: A total of 601 pediatric patients (n = 52), NAI therapy (n = 154), GC therapy (n = 123), and Both therapies (n = 272). Results: In a multivariate analysis with adjustment for confounding variables, the post-admission fever duration was not significantly different among the four patient groups. The post-admission fever duration tended to shorten with increasing age, longer pre-admission fever duration, and incidence of influenza A virus infection and lower respiratory tract infection. The type of administered treatment showed no significant effects on the post-admission fever duration in any subgroups according to patient age, pre-admission fever duration, influenza virus subtype, and clinical diagnosis. Conclusions: Symptomatic treatment rather than antiviral or GC therapy seems to be sufficient for patients with non-severe influenza, although the effects of NAI therapy and GC therapy according to their administered time and dose should be further evaluated.

This study aimed to determine the subjects for bacterial multiplex polymerase chain reaction (mPCR) testing and to interpret the mPCR test results based on patients’ clinical symptoms and diagnoses. The medical records of 710 pediatric patients who underwent a bacterial mPCR test were retrospectively reviewed. Clinical characteristics and mPCR test results were compared between patients with positive (n = 199) and negative mPCR test results (n = 511) and between patients with invasive pathogens (n = 95) and toxigenic pathogens (n = 70). Positive mPCR test results were significantly associated with older age (p &lt, 0.001), diagnosis of acute gastroenteritis (p = 0.021), presence of hematochezia (p &lt, 0.001), and absence of cough (p = 0.004). The diagnosis of acute gastroenteritis (p = 0.003), presence of fever (p = 0.027) and diarrhea (p = 0.043), and higher C-reactive protein levels (p = 0.025) were significantly associated with the identification of invasive pathogens in patients with positive mPCR test results. Thus, selective bacterial mPCR testing should be performed based on the patients’ clinical symptoms and diagnoses, and the results should be interpreted in consideration with identified pathogens.

The aim of the present study is to re-evaluate the clinical application of two-times serologic immunoglobulin M (IgM) tests using microparticle agglutination assay (MAA), an enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) assay in diagnosing Mycoplasma pneumoniae (MP) infection. A retrospective analysis of 62 children with MP pneumonia during a recent epidemic (2019–2020) was conducted. The MAA and ELISA immunoglobulin M (IgM) and IgG measurements were conducted twice at admission and around discharge, and MP PCR once at presentation. Diagnostic rates in each test were calculated at presentation and at discharge. The seroconverters were 39% (24/62) of patients tested by MAA and 29% (18/62) by ELISA. At presentation, the diagnostic positive rates of MAA, ELISA, and PCR tests were 61%, 71%, and 52%, respectively. After the second examination, the rates were 100% in both serologic tests. There were positive correlations between the titers of MAA and the IgM values of ELISA. The single serologic IgM or PCR tests had limitations to select patients infected with MP in the early stage. The short-term, paired IgM serologic tests during hospitalization can reduce patient-selection bias in MP infection studies.

BACKGROUND: Recently, four influenza viruses are circulating worldwide: A(H1N1)pdm09, A(H3N2), B/Victoria, and B/Yamagata. However, information on the clinical differences among pediatric patients infected with four recently circulating influenza viruses is sparse. METHODS: Medical records of pediatric patients (

Monitoring regional antibiotic resistance patterns of uropathogens are important for deciding suitable empirical antibiotics for urinary tract infections (UTIs) in children. This study aimed to investigate regional differences in antimicrobial susceptibility patterns of E. coli and Klebsiella spp. in children below 24 months old, diagnosed with their first episode of UTI, and to find factors associated with an increased risk for UTI caused by extended-spectrum &beta, lactamase (ESBL)-producing uropathogens. This was a retrospective cohort study of children diagnosed between 2011 and 2017 in four different hospitals located in four different regions of South Korea, regions A, B, C, and D. The government&rsquo, s big data repository was used to acquire data on regional antibiotic prescriptions. The pooled antimicrobial susceptibilities of E. coli and Klebsiella spp. (n = 2044) were as follows: ampicillin&ndash, sulbactam (61.0%), 3rd generation cephalosporin (3C) (82.8%), and trimethoprim&ndash, sulfamethoxazole (72.0%). Multivariate analysis showed that children diagnosed at hospital A (OR, 1.8, 95% confidence interval [CI], 1.2&ndash, 2.6, P = 0.002) and every year that increased in the study period (OR, 1.1, 95% CI, 1.1&ndash, 1.2, P &lt, 0.001) were factors associated with an increased risk for UTIs with ESBL-producers. Regions A and B had significantly higher amounts of oral 3Cs prescribed compared to regions C and D (P = 0.009), which correlate with hospitals in the regions that had higher proportions of UTIs with ESBL-producing uropathogens (A and B vs. C and D, P &lt, 0.001). Therefore, children in certain regions are at a higher risk for UTIs caused by ESBL-producers compared to other regions, which correlate with regions that had higher amounts of oral 3Cs prescribed.

Background This study aimed to investigate recent epidemiologic features of Kawasaki disease (KD) in South Korea. Methods The ninth triennial nationwide questionnaire survey collected data on the demographic findings, symptoms and signs, treatment patterns and coronary artery complications of acute-phase KD occurred in 2015-2017 from 98 hospitals with pediatric residency programs and 108 community hospitals without residency programs. Results We received data from 93 of the 98 hospitals (response rate: 94.9%) with residency programs and 75 of the 108 community-based children's hospitals (response rate: 69.4%) without residency programs. In the 3-year survey period, a total of 15,378 (5449 in 2015, 5171 in 2016 and 4758 in 2017) cases of KD were reported. The mean age at diagnosis was 33.0 ± 24.8 months (range: 0-205 months), and the male-to-female ratio was 1.41:1. The overall KD incidence was 196.9 (202.2 in 2015, 197.1 in 2016 and 191.0 in 2017) per 100,000 younger than 5 years population. Recurrent cases were 4.85%. KD occurred more frequently during winter (December-January) and late spring (May-June). Intravenous immunoglobulin (IVIG) was administered to 95% of the patients; nonresponder rate for the first IVIG was 14.8%. Coronary artery aneurysms and giant coronary artery aneurysms (internal diameter >8 mm) occurred in 1.7% and 19 patients, respectively. Two patients died due to multiorgan failure and hepatic encephalopathy. Conclusion Peak incidence of KD in South Korea was 202.2 per 100,000 younger than 5 years population (2015), and the incidence of giant coronary artery aneurysm decreased to 0.09% (2017).

Purpose This study aimed to analyse laboratory values according to fever duration, and evaluate the relationship across these values during the acute phase of Kawasaki disease (KD) to aid in the early diagnosis for early-presenting KD and incomplete KD patients. Methods Clinical and laboratory data of patients with KD (n=615) were evaluated according to duration of fever at presentation, and were compared between patients with and without coronary artery lesions (CALs). For evaluation of the relationships across laboratory indices, patients with a fever duration of 5 days or 6 days were used (n=204). Results The mean fever duration was 6.6±2.3 days, and the proportions of patients with CALs was 19.3% (n=114). C-reactive proteins (CRPs) and neutrophil differential values were highest and hemoglobin, albumin, and lymphocyte differential values were lowest in the 6-day group. Patients with CALs had longer total fever duration, higher CRP and neutrophil differential values and lower hemoglobin and albumin values compared to patients without CALs. CRP, albumin, neutrophil differential, and hemoglobin values at the peak inflammation stage of KD showed positive or negative correlations each other. Conclusion The severity of systemic inflammation in KD was reflected in the laboratory values including CRP, neutrophil differential, albumin, and hemoglobin. Observing changes in these laboratory parameters by repeated examinations prior to the peak of inflammation in acute KD may aid in diagnosis of early-presenting KD patients.

Recurrent macrophage activation syndrome (MAS) is very rare. We present the case of an adolescent boy with human leukocyte antigen (HLA) B27-positive ankylosing spondylitis (AS), who experienced episodes of recurrent MAS since he was a toddler. A 16-year-old boy was admitted because of remittent fever with pancytopenia and splenomegaly after surgical intervention for an intractable perianal abscess. He had been diagnosed with hemophagocytic lymphohistiocytosis (HLH) 4 different times, which was well controlled with intravenous immunoglobulin and steroids since the age of 3. We were unable to identify the cause for the HLH. He remained symptom-free until the development of back pain and right ankle joint pain with swelling at 15 years of age. He was diagnosed with HLA B27-positive AS with bilateral active sacroiliitis. He showed symptom aggravation despite taking naproxen and methotrexate, and the symptoms improved with etanercept. On admission, his laboratory data showed leukopenia with high ferritin and triglyceride levels. Bone marrow biopsy examination showed histiocytic hyperplasia with hemophagocytosis. There was no evidence of infection. He received naproxen alone, and his symptoms and laboratory data improved without any other immunomodulatory medications. Genetic study revealed no primary HLH or inflammasome abnormalities. In this case, underlying autoimmune disease should have been considered as the cause of recurrent MAS in the young patient once primary HLH was excluded.

Background Childhood-onset Systemic Lupus Erythematosus is a rare disease, with more than 50% of patients presenting with cytopenia of a decrease in at least one cell line. Objectives The purpose of this study was to evaluate whether clinical characteristics differed according to hematologic manifestation. Methods We retrospectively reviewed the presenting clinical and laboratory manifestations for 40 pediatric SLE patients (mean age 13.4 years, range 0-18 years), with leukopenia (n=12) and thrombocytopenia (n=15). Variables including age, inflammatory markers (ESR and CRP), prothrombin time, complement system (C3, C4 and CH50), immunoglobulin (IgG, IgA and IgM), Lupus anticoagulant ratio, antinuclear antibody, anti-phospholipid antibody, anti-platelet antibodies, anti β2-glycoprotein antibody, anti-cardiolipin antibody, anti-smith antibody and anti-dsDNA antibody levels were compared according to grouping by presence of leukopenia ( Results Patients with cytopenia showed younger age at diagnosis than without (mean 13.1 vs. 15.2 years, p=0.0031 for leukopenia and 12.8 vs. 15.2 years, p=0.014 for thrombocytopenia), although the onset of puberty might not contribute to cytopenia. Patients with leukopenia showed lower C3 level than without (mean 44.7 vs. 73.7, p=0.013). Patients with thrombocytopenia showed lower anti-dsDNA titer than without (mean 94.1 vs. 259.8, p=0.038), and was more often negative for anti-platelet antibody (Ib/IX). There were no statistical differences among other variables. Also, there was no significant difference in one cell line decrement compared with both. Conclusion Pediatric SLE patients with leukopenia and thrombocytopenia in our study may independently decrease the levels of C3 and anti-dsDNA/anti-platelet (Ib/IX) antibody, suggesting respective pathologic pathways that do not affect each other. Disclosure of Interests None declared

Antibiotics’ effect on Mycoplasma pneumoniae (MP) infection still remains controversial. A prospective study of 257 children with MP pneumonia during a recent epidemic (2015-2016) was conducted. All MP pneumonia patients were treated with corticosteroids within 24-36 h after admission. Initially, oral prednisolone (1 mg/kg) or intravenous methylprednisolone (IVMP) (1-2 mg/kg) was administered for mild pneumonia patients, and IVMP (5 -10 mg/kg/day) for severe pneumonia patients. If patients showed persistent fever for 36-48 hours or disease progression, additive IVMP (5 mg/kg or 10 mg/kg) was given. Eighty-five patients received only a broad-spectrum antibiotic without macrolide. The mean age and the male:female ratio were 5.6 ± 3.1 years, respectively. Seventy-four percent of patients (190/257) showed immediate defervescence within 24 h, and 95.7% (246/257) of patients showed defervescence within 72 h with improvements in clinical symptoms. Eight patients who received additive IVMP also showed clinical improvement within 48 h without adverse reactions. There were no clinical or laboratory differences between patients treated with a macrolide (n = 172) and without (n = 85). Early corticosteroid therapy might reduce disease morbidity and prevent disease progression in MP pneumonia patients without side effects, and antibiotics may have limited effects on MP infection.

Antibiotics&rsquo, effect on Mycoplasma pneumoniae (MP) infection still remains controversial. A prospective study of 257 children with MP pneumonia during a recent epidemic (2015&ndash, 2016) was conducted. All MP pneumonia patients were treated with corticosteroids within 24&ndash, 36 h after admission. Initially, oral prednisolone (1 mg/kg) or intravenous methylprednisolone (IVMP, 1&ndash, 2 mg/kg) was administered for mild pneumonia patients, and IVMP (5&ndash, 10 mg/kg/day) for severe pneumonia patients. If patients showed a persistent fever for 36&ndash, 48 h or disease progression, additive IVMP (5 mg/kg or 10 mg/kg) was given. Thirty-three percent of patients received only a broad-spectrum antibiotic without a macrolide. The mean age and the male-to-female ratio was 5.6 &plusmn, 3.1 years and 1:1, respectively. Seventy-four percent of patients showed immediate defervescence within 24 h, and 96% of patients showed defervescence within 72 h with improvements in clinical symptoms. Three percent of patients (8/257) who received additive IVMP also showed clinical improvement within 48 h without adverse reactions. There were no clinical or laboratory differences between patients treated with a macrolide (n = 172) and without (n = 85). Early corticosteroid therapy might reduce disease morbidity and prevent disease progression in MP pneumonia patients without side effects, and antibiotics may have limited effects on MP infection.

It is unknown whether epidemiological or clinical characteristics of Henoch-Schönlein purpura (HSP) have changed over time. This study aimed at evaluating the epidemiological and clinical changes of HSP during 3 decades.We retrospectively analyzed the data of 515 children with HSP (0-15 years of age) between 1987 and 2015. We compared the two HSP patient groups: those admitted from 1987 to 1996 (group A, 238 cases) and those admitted from 2006 to 2015 (group B, 98 cases), apart a decade.In total 515 patients, the mean age was 6.5 ± 3.0 years and the male-to-female ratio was 1.2:1 (278:237). The age distribution showed a peak at age 5 with a bell-shaped distribution pattern. The annual number of cases varied in each year with a trend of reduced cases in the recent decade. There were less cases during the summer season. Purpura, gastrointestinal involvement, joint involvement, and renal involvement were found in 100%, 56%, 38%, and 18% of the patients, respectively. In comparison between the two groups, there were similar findings in mean age, age distribution, and seasonal distribution. However, the hospitalization stay was longer, and the proportion of recurrent cases (14 cases vs. 0 case) and proteinuria (15% vs. 3%) were higher in the group A than in the group B.Long-term epidemiologic features of HSP were similar to those in other countries. Clinical manifestations of HSP showed a trend towards a less severe clinical phenotype over time in Deajeon, Korea. Key Points • It is unknown whether epidemiological and clinical traits of Henoch-Schönlein purpura (HSP) have changed over time. • We reported that clinical manifestations of HSP have changed to milder phenotype through a long-term observation of three decades at a single hospital in Daejeon, South Korea. • Clinical phenotype of infection-related diseases, including HSP, may be changed over time, and the etiology and the reason of clinical changes over time remain to be solved.

Background: Kawasaki disease (KD) may be associated with infection of unknown pathogen(s). For predicting of the etiology of KD, we evaluated epidemiological characteristics in KD, common infectious diseases and immune-mediated diseases in childhood. Methods: We respectively, reviewed the data of patients with KD, influenza, aseptic meningitis, exanthem subitum (ES), Mycoplasma pneumoniae (MP) pneumonia, acute pyelonephritis (APN), Henoch-Schonlein purpura (HSP), acute poststreptococcal glomerulonephritis (APSGN), and childhood asthma. We compared and interpreted epidemiological data across the groups. Results: In age distribution, KD, APN, and ES showed a similar pattern in that majority of patients were infants or young children, and other diseases showed a relatively even age-distribution which had a peak age, mainly 5-6 years, with bell-shape patterns. In annual-case pattern, there were epidemic years in aseptic meningitis and MP pneumonia, and the fluctuated annual cases were seen in other diseases. The trends of decreasing cases were seen in APSGN, HSP, and childhood asthma in recent years. In seasonal frequency, influenza or aseptic meningitis occurred in mainly winter or summer season, respectively. HSP and APSGN cases had less in summer, and KD, APN, and ES showed relatively even occurrence throughout a year without significant seasonal variations. Conclusions: Our results suggest that KD agents may be associated with normal flora that are influenced by environmental changes, since pathogens of APN and ES could be regarded as normal flora that originate from the host itself or ubiquitously existing human reservoirs.

Purpose: The incidence of acute poststreptococcal glomerulonephritis (APSGN) in Korea has changed. This study aimed to evaluate the epidemiological and clinical changes of APSGN observed in a single Korean institution over two decades. Methods: We retrospectively analyzed the data of 99 children (0-15 years of age) who were admitted to our institution with APSGN between 1987 and 2013. The patients were selected based on the depression of serum complement 3 (C3, 250 IU/dL) as evidence of previous streptococcal infection. Results: In the 99 patients, the mean age was 8.3 ± 2.7 years, and the male-tofemale ratio was 2.2:1 (66:30). The annual number of cases fluctuated markedly, and most cases were observed during the late autumn and winter months. However, there have been few cases reported in the past 5 years. Clinical manifestations at presentation, including hypertension and generalized oedema, and the duration of hospitalization were higher and longer in patients admitted during the first half of the study period than during the most recent half-period, suggesting a more severe clinical course in the former group. Conclusions: APSGN has become a rare disease in Korea with a trend towards a less severe clinical course. This finding suggests that the prevalence of infection-related immune-mediated diseases could change over-time, together with environ mental and possibly pathogen-host relationship changes.

Background Ascending infections are thought as the main route of infection in acute pyelonephritis (APN). However, among patients diagnosed with APN, a subset has atypical presentation unexplainable by ascending routes of infections. This study aimed to review 8 cases initially diagnosed as APN, however presenting with no or minimal pyuria and presenting as acute focal bacterial nephritis (AFBN). Methods This was a retrospective cohort study of children Results During the 11-year period, of the total of 359 patients were diagnosed with the first episode of APN. Of these, 8 were re-diagnosed as AFBN. The mean age was 9.8 years old (1.9–17.4). Abdominal pain with nausea and vomiting were chief complaints (62.5%), and none had urinary symptoms including dysuria, incontinence, or increased frequency. Initial urinalysis in all the patients showed WBC Conclusion Lack of urinary symptoms, insignificant pyuria, and CT findings of AFBN support the possibility of an alternative route of infection, other than the ascending route. Disclosures All authors: No reported disclosures.

Rotavirus (RV) is one of the most important viral etiologic agents of acute gastroenteritis (AGE) in children. Although effective RV vaccines (RVVs) are now used worldwide, novel genotypes and outbreaks resulting from rare genotype combinations have emerged. This study documented RV genotypes in a Korean population of children with AGE 5 yr after the introduction of RVV and assessed potential genotype differences based on vaccination status or vaccine type. Children less than 5-yr-old diagnosed with AGE between October 2012 and September 2013 admitted to 9 medical institutions from 8 provinces in Korea were prospectively enrolled. Stool samples were tested for RV by enzyme immunoassay and genotyped by multiplex reverse-transcription polymerase chain reaction. In 346 patients, 114 (32.9%) were RV-positive. Among them, 87 (76.3%) patients were infected with RV alone. Eighty-six of 114 RV-positive stool samples were successfully genotyped, and their combinations of genotypes were G1P[8] (36, 41.9%), G2P[4] (12, 14.0%), and G3P[8] (6, 7.0%). RV was detected in 27.8% of patients in the vaccinated group and 39.8% in the unvaccinated group (P=0.035). Vaccination history was available for 67 of 86 cases with successfully genotyped RV-positive stool samples; RotaTeq (20, 29.9%), Rotarix (7, 10.4%), unvaccinated (40, 59.7%). The incidence of RV AGE is lower in the RV-vaccinated group compared to the unvaccinated group with no evidence of substitution with unusual genotype combinations. Graphical Abstract

PurposeMycoplasma pneumoniae (MP) pneumonia epidemics have occurred in 3- to 4-year cycles in Korea. We evaluated the epidemiologic characteristics of MP pneumonia in Daejeon, Korea, from 2003 to 2012.MethodsWe retrospectively analyzed 779 medical records of children (0-15 years of old) with MP pneumonia admitted to our institution and compared the data from 3 recent epidemics.ResultsIn 779 patients, the mean age and male-to-female ratio were 5.0±2.2 years and 1:1, and most cases were observed in autumn. There were three epidemics during the study period, in 2003, 2006-2007, and 2011. In our comparison of the three epidemics, we found no differences in mean age, the male-to-female ratio, hospital stay, or the rate of seroconverters during hospitalization. All three epidemics began in early summer and peaked in September 2003 and 2011 and in October 2006 and then gradually decreased until the next year's spring season, although the 2006 epidemic extended further into 2007. The peak age groups in the children in 2003 and 2006 were 3-6 year-olds (57.5% and 56%, respectively), but in the 2011 epidemic, the peak group was 1-4 year-olds (46.5%). The proportion of the 10 years of age group was 5.2%, 13.8%, and 14.8% of total patients, respectively.ConclusionMP pneumonia outbreaks occurred every 3-4 years. The pattern of 3 recent epidemics was similar in demographic characteristics and seasonality with some variations in each outbreak.

Kawasaki disease (KD) may be an acute systemic immune-mediated disease which occurs after infection of unknown KD pathogen(s). The aim of this study is to evaluate the changes in platelet count and immunoglobulin (Ig) levels (IgG, IgM, IgA, and IgE) during hospitalization. Forty-three patients with complete KD who received intravenous Ig at 2 g/kg were enrolled in South Korea. The platelet count and Ig levels of the patients were examined twice at presentation and around discharge (mean 6.2 ± 2.4 days apart) and the relationships between platelet level and Ig levels were evaluated. The mean patient age was 31 ± 18 months; 28 patients were male and 15 were female. The values of all parameters measured, with the exception of IgE, were significantly increased at the second examination compared with their values at presentation. These values gradually increased over time after fever onset, over periods ranging from 2 to 16 days. The extent by which platelet levels increased over these 2 time points was correlated with the extents by which IgG (P

Background Kawasaki disease (KD) becomes one of the common diseases in Korea. Changes in clinical features and laboratory findings of KD were evaluated over a period of 10 years. Methods We reviewed the medical records of KD patients and compared the clinical and laboratory features of two KD patient groups: those admitted from 2000 to 2004 (group A, 284 cases) and those admitted from 2010 to 2014 (group B, 331 cases). Results There were a total of 615 KD patients (mean age: 29.7 months; male-to-female ratio = 1.6:1), including 228 incomplete KD patients. Incomplete KD patients had milder values in some laboratory indices. The preadmission and total fever durations were longer in group A than in group B. The proportion of incomplete KD was higher in group B, but incidence of coronary artery lesions (CALs) was lower. For laboratory indices, the C-reactive protein and follow-up platelet values were lower, and the hemoglobin and albumin values were higher in group B. The same clinical and laboratory findings were confirmed in the KD subgroups; those with the same fever duration of 5 or 6 days and same ages, those with complete KD, and those with incomplete KD in the two different time periods. Conclusions Our findings suggest that clinical features of KD tend to be milder over time and manifest in a higher incidence of incomplete KD, lower incidence of CALs, and less severe laboratory findings in recent KD patients in Korea compared with their historic counterparts.

Background and Aims CAPLS is a multiple thrombi of small vessels affecting viscera. Patients had previous evidence of APLS. CAPLS was precipitated by infection, invasive procedures. The clinical presentation was involving the cardiopulmonary, CNS, abdomem. Thrombocytopenia and hemolytic anaemia were frequent. Anticardiolipin antibodies were present in almost. The outcome can be disastrous. Methods Case: 10-year-girl had been developed petechiae on Aug 10, 2009. Patelet 2000, Hb 12.0. The diagnosis was ITP and she received the IVIG. But anaemia was developed on Aug 31, 2009. Platelet 48,000. Hb 8.9. The diagnosis was Acquired hemolytic anaemia. On Sept 21, 2009 the Hb 10.0, reticulocyte 11.0% and Cooms’ (+), FANA (++), anti-dsDNA (-). The diagnosis was Evans’ syndrome. The following lab were anti-cardiolipin IgG (+), IgM (+), IgA (-), Lupus anticoagulant (+), anti-beta2 GPI IgG (+), IgM (+) on Oct 14, 2009. The final diagnosis was SLE with antiphosolipid syndrome. Gangrene affecting the right 5th toe on Jan 2014 and gangrened toe was autoamputated on Dec 2014. CT angiogram was performed on Apr 2014. There was superficial occusion on right femoral vein. On July 2014 the disease was flared. Hemolytic anaemia (Hb 7.7) and jaundice developed. Chest CT revealed SLE myocarditis and abdomen CT was bowel SLE. Results On Sept 2014, catastrophic APS was developed. Platelet 5,000. aPTT 99.3 s. Plasma pheresis was done for 7 times, but the platelet count did not change. Rituximab was injected 4 times. Platelet was 4000 thru 99 000 on Nov 2014. After then platelet was well controlled. Conclusions This rituximab response to therapy.

Purpose The introduction of the mumps vaccine has dramatically reduced the number of mumps cases, but outbreaks have recently occurred among highly vaccinated populations in developed countries. Epidemiological and clinical characteristics of patients with mumps admitted between 1989 and 2012 in a single hospital in Korea are described in the present study. Methods We retrospectively evaluated inpatients with mumps between 1989 and 2012 and outpatients and inpatients with mumps in 2011-2012. Results A total of 152 patients with mumps were admitted between 1989 and 2012, and 163 patients were recorded in 2011-2012. The highest number of admitted cases occurred in 1998 and 2012 (35 and 34 cases, respectively). Among the patients admitted in 2011-2012, the highest frequency was observed among people aged 15-19 years, and low frequency was observed in those aged 20 years, compatible to the city data and national data. In patients admitted to our department in 1998 (35 cases) and in 2010-2012 (27 cases), there were significant differences in the mean age and the rate of secondary measles-mumps-rubella (MMR) vaccination, but had similar clinical features, including complications, except aseptic meningitis. Antimumps immunoglobulin (Ig) G was positive in 83% and 100%, and IgM was positive in 67% and 41%, respectively, in the two periods. Conclusion In Korea, recent mumps outbreaks have occurred mainly among secondary school students who received two doses of the MMR vaccine. The vaccinees might have a modified immune reaction to viral insults, manifesting modified epidemiological and clinical features.

Chronic granulomatous disease (CGD) is a rare hereditary disorder that is characterized by a greatly increased susceptibility to life-threatening bacterial and fungal infections. CGD is caused by mutations in any one of the genes encoding subunits of phagocyte NADPH oxidase. X-linked CGD, more than half of all CGD cases, is caused by mutations in CYBB gene encoding gp91-phox subunit. We identified the mutations in the CYBB gene of 29 Korean patients with X-linked CGD from 26 unrelated families. Twenty-three mutations were identified: five splice site mutations (c.45 + 1G > C, c.141 + 5G > A, c.897 + 2T > C c.1461 + 1G > T, c.1586 + 2T > A), four frameshift mutations (c.27dupG, [c.737A > C; c.742delA], c.742dupA, c.1636 del C), seven non-sense mutations (c217C > T, c.469C > T, c.676C > T, c.868C > T, c.1222G > T, c.1272G > A, c.1281T > A), five missense mutations (c.164 C > A, c.422T > C, c.665 A > G, c.1012C > T, c.1461G > T) and two gross deletions. Eight out of 23 mutations identified in this study are novel mutations: two splice mutations(c.897 + 2T > C, c.1586 + 2T > A), two frame shift mutations ([c.737A > C; c.742delA], c.1636 del C), two nonsense mutations (c.1222G > T, c.1281T > A), one missense mutation (c.1461G > T), one gross deletion (c.1667_1629 del.). Our results confirmed that mutations of CYBB gene in the X-CGD are very heterogeneous and not show the peculiarity of the ethnic group.

BACKGROUND The goal of this study is to evaluate the changes in the epidemiologic and clinical features of Kawasaki disease (KD) in a period of 20 years. METHODS We compared the epidemiologic features of 3 KD patient groups: those admitted from 1987 to 1990 (122 cases), from 1997 to 2000 (137 cases) and from 2007 to 2010 (102 cases). For clinical features, we reviewed the medical records of patients admitted from 1996 to 2000 (141 cases) and from 2006 to 2010 (121 cases). RESULTS There were a total of 772 KD patients during the study period (mean age: 27.2 months; male-to-female ratio: 1.6:1). There were some variations in the mean ages (23.8, 27.8 and 30 months), in the male-to-female ratios (1.9:1, 1.3:1 and 1.8:1) and in the age distributions, including the patients of ages 5 years, but the differences were not statistically significant across the groups. The seasonal distributions were relatively consistent with some variations. In clinical features, the preadmission and total fever durations were shorter (P < 0.001, respectively), and the proportions of incomplete KD tended to increase, and the rates of coronary artery aneurysm tended to decrease in recently admitted patients. CONCLUSIONS There were no significant changes in the demographic and seasonal features of KD, although the evaluation of the clinical features showed shorter fever duration suggestive of improved identification and treatment of KD over time.

ObjectiveThis study was aimed to evaluate epidemiological and clinical relationship betweenMycoplasma pneumoniae(MP) infection and childhood recurrent wheezing episode (RWE).DesignRetrospective case note review.SettingPaediatric department at a single Korean institution.ParticipantsConsecutive admitted patients with MP pneumonia and RWE (0–15 years of age) between 2003 and 2014.MethodsThe retrospective medical records of patients with (MP) pneumonia (n=793 for epidemiological analysis and n=501 for clinical analysis) and those with RWE (n=384) from 2003 to 2014 were analysed. Diagnosis of MP pneumonia was made based on two-times titration of IgM antibody during hospitalisation. An RWE patient was defined as one with expiratory wheezing with at least one or more wheezing episodes based on medical records.ResultsDuring three MP pneumonia epidemics, there were no corresponding increases of patients with RWE in the epidemic years. In the 501 MP pneumonia patients, 52 (10.4%) had wheezing at presentation and 15 (3%) had RWE. The MP pneumonia patients with wheezing at presentation (n=52) were younger and were more likely to have an allergic disease history than those without wheezing (n=449). Among wheezing patients at presentation, 10 patients had previously RWE history. In a follow-up study, 13 patients (including 5 RWE) with initial wheezing and 25 patients (including 2 RWE) without wheezing had wheezy episodes after discharge. Among the total 501 patients, it was estimated that at least 31 MP pneumonia patients (6.2%) showed recurrent wheezing after initial MP infection.ConclusionsA small part of children with MP pneumonia showed recurrent wheezing after MP pneumonia, and patients with RWE had a greater likelihood of experiencing wheezing when they had an initial MP infection. However, there were no increased admitted patients with RWE in MP pneumonia epidemic periods because of rarity of MP reinfection in children including patients with RWE or asthma.

This study represents the first epidemiological study based on the national registry of primary immunodeficiencies (PID) in Korea. Patient data were collected from 23 major hospitals. A total of 152 patients with PID (under 19 yr of age), who were observed from 2001 to 2005, have been entered in this registry. The period prevalence of PID in Korea in 2005 is 11.25 per million children. The following frequencies were found: antibody deficiencies, 53.3% (n = 81), phagocytic disorders, 28.9% (n = 44); combined immunodeficiencies, 13.2% (n = 20); and T cell deficiencies, 4.6% (n = 7). Congenital agammaglobulinemia (n = 21) and selective IgA deficiency (n = 21) were the most frequently reported antibody deficiency. Other reported deficiencies were common variable immunodeficiencies (n = 16), X-linked agammaglobulinemia (n = 15), IgG subclass deficiency (n = 4). Phagocytic disorder was mostly chronic granulomatous disease. A small number of patients with Wiskott-Aldrich syndrome, hyper-IgE syndrome, and severe combined immunodeficiency were also registered. Overall, the most common first manifestation was pneumonia. This study provides data that permit a more accurate estimation PID patients in Korea.