Population-based retrospective cohort study on community-acquired pneumonia hospitalization in children with a ventricular septal defect.

The cohort consisted of 9400 exposed children diagnosed with ventricular septal defect (VSD). The risk of community-acquired pneumonia (CAP) or asthma with VSD was assessed using the Cox proportional hazard model with an inverse probability of treatment weighting. During a mean follow-up of 6.67 years (starting from 12 months after birth), there were 2100 CAP admission cases among exposed patients (incidence rate: 33.2 per 1000 person-years) and 20,109 CAP admission cases among unexposed children (incidence rate: 29.6 per 1000 person-years), with hazard ration of 1.09 (95% CI 1.04-1.14).

Factors influencing the quality of life in children with atopic dermatitis in Korea: A multicenter cross-sectional study.

Background: There is a lack of studies about which factors affect the quality of life (QoL) in children with atopic dermatitis (AD), although it is well known that AD has considerably negative effects on their QoL. Objective: This study aimed to measure the QoL in children with AD and identify the factors that affect their QoL. Methods: A questionnaire derived from the Children's Dermatology Life Quality Index (CDLQI) was used to measure QoL. Family history, allergic comorbidities, exacerbation-related factors, time of exacerbation, and previous and current treatment were also evaluated. The total immunoglobulin E (IgE) level and specific IgE sensitization were determined by the multiple allergen simultaneous test, allergy test, or skin-prick test. AD severity was categorized into mild, moderate, and severe based on treatments. Results: In total, 254 children (46.4 months, 53% boys) from seven hospitals completed the survey. The mean CDLQI score was 7.2 ± 5.5 (total score range of 0-30). The respondents were divided into three groups according to their QoL score distribution, with 0 - 4 points (n = 84), 5 - 9 points (n = 90), and ≥10 points (n = 80) representing good, fair, and poor QoL, respectively. The more severe AD showed the higher CDLQI score significantly (p = 0.001). Compared with other groups, children with poor QoL were more sensitized to inhalant allergens (odds ratio [OR] 1.29 [95% confidence interval {CI}], 1.03 - 1.62) and had more exacerbating factors (OR 1.26 [95% CI, 1.04 - 1.54]), which included inhalation allergen-related exacerbating factors (OR 2.54 [95% CI, 1.23 - 5.23), even after adjusting for age, total IgE, body mass index, severity, and use of moisturizer. The concordance between animal sensitization and an exacerbating factor, including dog and cat, was fair, with 0.39 κ and 0.85 accuracy. Conclusion: This study showed that impaired QoL in children with AD is associated with inhalant allergen sensitization and inhalant allergen-related exacerbation factors. Especially, dog and cat sensitization was a significant exacerbating factor. The inhalation-related exacerbation factors, including animal allergens, might be addressed to improve AD management in children.

The KAAACI Guidelines for Sublingual Immunotherapy.

Allergen immunotherapy is regarded as the only disease-modifying treatment option for various allergic conditions, including allergic rhinitis and asthma. Among the routes of administration of allergens, sublingual immunotherapy (SLIT) has gained clinical interest recently, and the prescription of SLIT is increasing among patients with allergies. After 30 years of SLIT use, numerous pieces of evidence supporting its efficacy, safety, and mechanism allows SLIT to be considered as an alternative option to subcutaneous immunotherapy. Based on the progressive development of SLIT, the current guideline from the Korean Academy of Asthma, Allergy, and Clinical Immunology aims to provide an expert opinion by allergy, pediatrics, and otorhinolaryngology specialists with an extensive literature review. This guideline addresses the use of SLIT, including 1) mechanisms of action, 2) appropriate patient selection for SLIT, 3) the currently available SLIT products in Korea, and 4) updated information on its efficacy and safety. This guideline will facilitate a better understanding of practical considerations for SLIT.

KAAACI Guidelines for Allergen Immunotherapy.

Allergen immunotherapy (AIT) is a causative treatment for various allergic diseases such as allergic rhinitis, allergic asthma, and bee venom allergy that induces tolerance to offending allergens. The need for uniform practice guidelines in AIT is continuously growing because of the increasing discovery of potential candidates for AIT and evolving interest in new therapeutic approaches. This guideline is an updated version of the Korean Academy of Asthma Allergy and Clinical Immunology recommendations for AIT published in 2010. This updated guideline proposes an expert opinion by allergy, pediatrics, and otorhinolaryngology specialists with an extensive literature review. The guideline deals with basic knowledge and methodological aspects of AIT, including mechanisms, clinical efficacy, patient selection, allergens extract selection, schedule and doses, management of adverse reactions, efficacy measurements, and special consideration in pediatrics. The guidelines for sublingual immunotherapy will be covered in detail in a separate article.

Associations Between Phthalate, Eosinophil, and Aeroallergen Sensitization in Schoolchildren.

BACKGROUND: Phthalates and bisphenol A (BPA) are endocrine-disrupting chemicals and may cause immunological disorders in children. Therefore, according to the region, we investigated urinary phthalates and BPA levels and the relationship between urinary phthalate, aeroallergen sensitization, and eosinophil count during the coronavirus disease 2019 pandemic. METHODS: In total, 203 schoolchildren (134 residential and 69 industrial) aged 7-10 years were enrolled between July 2021 and July 2022. The BPA, metabolites of four high-molecular-weight phthalates (Σ4HMWP) and three low-molecular-weight phthalates (Σ3LMWP), were measured in the urine samples. Total eosinophil count and transepidermal water loss (TEWL) were also measured along with the skin prick test. RESULTS: The two groups had no differences in terms of BPA. The industrial group had significantly more plastic container usage, and there was a difference in the Σ3LMWP (P < 0.001) between the two groups but no difference in the Σ4HMWP (P = 0.234). The quartiles of urinary Σ4HMWP and Σ3LMWP (P < were not associated with the total eosinophil count, vitamin D level, or TEWL. After adjusting for cofactors, the quartiles of urinary Σ4HMWP and Σ3LMWP were significantly associated with total eosinophil count (P < 0.001) but not with aeroallergen sensitization or vitamin D. CONCLUSION: Exposure to phthalates was significantly associated with eosinophil count but not with aeroallergen sensitization or vitamin D. Therefore, reducing the use of plastic containers may effectively prevent exposure to phthalates and reduce Th2 cell-mediated inflammation in children.

Trends of vitamin D in asthma in the pediatric population for two decades: a systematic review.

Vitamin D exhibits anti-inflammatory properties through multiple mechanisms. Vitamin D deficiency is associated with increased inflammation, exacerbations, and overall worse outcomes in pediatric asthma and is observed in asthmatic children with obesity. In addition, given the increase in the prevalence of asthma over the last few decades, there has been enormous interest in vitamin D supplementation as a potential therapeutic option. However, recent studies have suggested no strong association between vitamin D levels or supplementation and childhood asthma. Recent studies have reported that obesity and vitamin D deficiency are associated with increased asthma symptoms. Thus, this review summarizes the findings of clinical trials regarding the role of vitamin D in pediatric asthma and analyzes the study trends of vitamin D over the past 2 decades.

Assessment of variables associated with prolonged admission duration in children with Mycoplasma pneumoniae pneumonia.

INTRODUCTION: Macrolide-resistant Mycoplasma pneumoniae (MRMP) has become prevalent in children. This study investigated the clinical and laboratory variables of MRMP and macrolide-sensitive M. pneumoniae (MSMP) and identified factors associated with prolonged hospital admission in children. METHODS: A prospective multicenter study was conducted in 1063 children <18 years old in July 2018-June 2020. The 454 had a positive M. pneumoniae polymerase chain reaction assay. RESULTS: Most subjects had MRMP (78.4%), and all mutated strains had the A2063G transition. We defined MRMP* (n = 285) as MRMP pneumonia requiring admission and MSMP* (n = 72) as MSMP pneumonia requiring admission. Patients with MRMP pneumonia were older, more likely to have segmental/lobar pneumonia, and had more febrile days than those with MSMP pneumonia. C-reactive protein (CRP), lactate dehydrogenase (LDH), and percentage neutrophils were more strongly associated with MRMP* than MSMP* groups. Percentage neutrophils, CRP, and alanine aminotransferase significantly changed between admission and follow-up measurements in patients with MRMP* (P < 0.05). The duration of admission positively correlated with the number of febrile days after initiation of antibiotic medication and laboratory variables (white blood cell count, CRP, and aspartate aminotransferase [AST]) (P < 0.05). Random forest analysis indicated that the number of febrile days after initiation of antibiotic medication, AST, and percentage neutrophils at admission was over five. CONCLUSIONS: This study indicated that children with M. pneumoniae pneumonia with a higher number of febrile days after initiation of antibiotic medication, AST, and percentage neutrophils at admission were more likely to have prolonged admission duration.

Classification of atopic dermatitis phenotypes according to allergic sensitization by cluster analysis.

A cluster study to classify atopic dermatitis (AD) phenotypes into subgroups is required to better understand and manage the disease owing to the heterogeneity of its clinical features. This study aimed to identify the phenotypic subgroups of childhood AD according to allergic sensitization. In 258 children with AD, hierarchical cluster analysis based on specific immunoglobulin (Ig) E sensitization revealed four distinct clusters. Cluster A (n = 71) revealed no IgE sensitization, whereas cluster B (n = 28) showed sensitization to egg white only. Cluster B was highly associated with early-onset AD (<3 months) and a family history of atopic diseases. Cluster C (n = 68) and D (n = 91), sensitized to multiple foods and inhalants, respectively, showed a higher prevalence of skin infection within the last 1 year than others. Cluster D was related to late-onset AD (>12 months) and had more atopic comorbidities. In addition, cluster D showed the most severely impaired health-related quality of life and more frequent use of immunosuppressants. Therefore, childhood AD can be classified into 4 clusters based on the allergic sensitization status, and clinical phenotypes and treatment strategy may be different according to clusters.

Gut Microbiome Characteristics in Mothers and Infants According to the Presence of Atopic Dermatitis.

Objective: The role of the gut microbiome in the onset and development of atopic dermatitis (AD) has been postulated. Thus, we investigated the gut microbial compositions in infants with and without AD and compared the gut bacterial flora of their mothers. Methods: The prospective and cross-sectional study participated in 44 pairs of mothers and children. We selected infants born via full-term normal vaginal delivery and no history of antibiotic or probiotic use and infection during the first three months of life. The 15 pairs, consisting of nine healthy infants and six AD infants, were included in this study. Fecal samples of mothers and infants were analyzed within 30 days of delivery and at 12 months, respectively. Microbes in the fecal samples of mothers and infants were subjected to analysis of 16S rRNA amplicon sequencing. Results: The abundance of specific taxonomic groups was notably different, but microbial diversity and phylogenetic distances were not significantly different in either maternal or infant groups according to the presence of infant AD. A total of 12 species were selected as differential species in infants with AD compared to healthy infants. Six species were significantly different in the mothers of infants with AD compared to the mothers of healthy infants. Akkermansia muciniphila was only detected in healthy infants and their mothers. Conclusion: The presence of Akkermansia muciniphila in mothers and children after vaginal delivery is associated with the onset and development of AD.

Analysis of national surveillance of respiratory pathogens for community-acquired pneumonia in children and adolescents.

BACKGROUND: Respiratory infections among children, particularly community-acquired pneumonia (CAP), is a major disease with a high frequency among outpatient and inpatient visits. The causes of CAP vary depending on individual susceptibility, the epidemiological characteristics of the community, and the season. We performed this study to establish a nationwide surveillance network system and identify the causative agents for CAP and antibiotic resistance in Korean children with CAP. METHODS: The monitoring network was composed of 28 secondary and tertiary medical institutions. Upper and lower respiratory samples were assayed using a culture or polymerase chain reaction (PCR) from August 2018 to May 2020. RESULTS: A total of 1023 cases were registered in patients with CAP, and PCR of atypical pneumonia pathogens revealed 422 cases of M. pneumoniae (41.3%). Respiratory viruses showed a positivity rate of 65.7% by multiplex PCR test, and human rhinovirus was the most common virus, with 312 cases (30.5%). Two hundred sixty four cases (25.8%) were isolated by culture, including 131 cases of S. aureus (12.8%), 92 cases of S. pneumoniae (9%), and 20 cases of H. influenzae (2%). The cultured, isolated bacteria may be colonized pathogen. The proportion of co-detection was 49.2%. The rate of antibiotic resistance showed similar results as previous reports. CONCLUSIONS: This study will identify the pathogens that cause respiratory infections and analyze the current status of antibiotic resistance to provide scientific evidence for management policies of domestic respiratory infections. Additionally, in preparation for new epidemics, including COVID-19, monitoring respiratory infections in children and adolescents has become more important, and research on this topic should be continuously conducted in the future.

Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study.

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.

The Relationship between Aeroallergen Sensitization and Chronic Cough in School-Aged Children from General Population.

OBJECTIVE: Determining sensitivity to allergens is an essential step in diagnosing children with allergic diseases. Chronic cough has remained poorly understood with causative triggers. The purpose of our study was to shed light on the relationship between sensitization to aeroallergens and chronic cough. METHODS: This population-based study examined children (aged 7 years to 13 years) between June and July 2016. The 1,259 children, 72 of whom (5.7%) had a chronic cough, and 1,187 of whom (94.3%) did not (controls), completed the questionnaire, but 1,051 children completed skin prick tests (SPTs) with eight aeroallergens. RESULTS: There were positive SPT results to at least 1 allergen in 549 children (52.2%). Sensitization to house dust mite (HDM) was most common (chronic cough = 46.9%; controls = 47.2%), followed by pollen (chronic cough = 21.9%; controls = 16.5%) in both groups, but there was no difference in allergic profile and sensitization to aeroallergen (P > 0.05 for all comparisons). Multivariable analysis with adjustment for confounding indicated that children who were in sensitization to pollen had an increased risk of chronic cough (aOR = 2.387; 95% CI: 1.115 to 5.111; P = 0.025). Multivariable analysis with adjustment for confounding indicated that children who were exposed to current smoking (aOR = 4.442; 95% CI: 1.831 to 10.776; P = 0.001) and mold (aOR = 1.988; 95% CI: 1.168 to 3.383; P = 0.011) were associated with chronic cough. CONCLUSION: Sensitization to pollen should be considered as a potential contributing factor to the development of chronic cough in school-aged children.

Abnormal iron status is independently associated with reduced oscillometric lung function in schoolchildren.

BACKGROUND: Associations between anemia and allergic diseases have been reported, but the relationship of iron deficiency with airway dysfunction in children remains unclear. We aimed to investigate the relationship between abnormal iron parameters and lung function in schoolchildren. METHODS: Four hundred and forty-five children (10-12 years-old) from 11 elementary schools in were enrolled. The relationships of different iron parameters (hemoglobin, serum iron, transferrin saturation, and serum ferritin) with lung function evaluated by impulse oscillometry (airways resistance at 5 Hz [Rrs5], 10 Hz [Rrs10], and the difference of Rrs5 and Rrs20 Hz [Rrs5-20]), and with exhaled nitric oxide (FeNO) were evaluated after adjustment for confounders including height, sex, and body mass index z-score, and for additional covariates that could affect airway function. RESULTS: Total airway dysfunction represented by Rrs5 was reduced in participants with low serum iron level (aß: -0.13, 95% CI: -0.23 to -0.03, p = 0.040) after adjustment for key confounders, but did not correlate with other iron profiles. Reduced oscillometric lung function recorded as Rrs5-20 was related with low serum iron and high serum ferritin, but the results were inconsistent after multiple comparisons. Associations were not observed with serum hemoglobin. CONCLUSIONS: Decreased serum iron level was related with airway dysfunction represented as oscillomteric Rrs5. Our results suggest a relationship of reduced lung function with abnormal iron status in children.

Association of serum lipopolysaccharide-binding protein level with sensitization to food allergens in children.

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates innate immune responses triggered by LPS. Recent studies indicated a positive correlation of circulating LBP level with chronic low-grade inflammation, a condition present in many non-communicable diseases. We determined the association of serum LBP concentration with allergic sensitization in a general pediatric population. Serum LBP was measured in a sample of children (n = 356; mean age = 9.6 ± 0.2 years) in this population-based cross-sectional study. Skin prick tests (SPTs) were performed to assess allergic sensitization to 22 common inhalant and food allergens. One hundred and seven children (30.1%) were nonsensitized, 160 (44.9%) were monosensitized, and 89 (25.0%) were polysensitized. Children who were mono- or polysensitized had a significantly higher median serum LBP level (25.5 ng/mL, inter-quartile range [IQR] 20.3-30.7) than those who were nonsensitized (20.3 ng/mL, IQR = 14.81-25.8, P < 0.0001). Multivariate logistic regression analysis with adjustment for confounders indicated that serum LBP level was positively associated with allergic sensitization overall (adjusted odds ratio [aOR] 1.041; 95% CI 1.007-1.076, P = 0.016), with sensitization to food allergens in particular (aOR 1.080, 95% CI 1.029-1.133, P = 0.002), but not with sensitization to aeroallergens (aOR 1.010, 95% CI 0.982-1.040, P = 0.467). LBP level was not associated with allergic diseases after adjustment. We suggest the possibility of sensitization to food allergens may be related to gut-derived low-grade inflammation, and large sized longitudinal investigations are needed to elucidate the relationship.

Association of serum lipid parameters with the SCORAD index and onset of atopic dermatitis in children.

BACKGROUND: The association between dyslipidemia and atopic dermatitis in children is unclear. This study investigated the association between dyslipidemia and atopic dermatitis in children by analysis of disease onset, risk factors, and disease severity. METHODS: Subset I examined 7-year-old children in elementary school (n = 248), and Subset II was a retrospective long-term follow-up hospital-based study (n = 52 725) conducted from 1986 to 2016 that used propensity score matching. In the Subset I study, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) were determined, and the SCORing Atopic Dermatitis (SCORAD) index was determined. In the Subset II study, the time of atopic dermatitis onset was determined for asymptomatic subjects whose TC levels were below or above 170 mg/dL. RESULTS: Our Subset I study indicated that children with atopic dermatitis (n = 69, 27.8%) had significantly higher levels of TC and TG, and that the SCORAD index had significant associations with high levels of TC and TG, and a low level of HDL-C. Our Subset II study (1722 with high TC and 6735 with normal TC after propensity score matching) indicated the high TC group had a greater hazard ratio (HR) for the onset of atopic dermatitis (consensus-based HR: 2.47; 95% CI: 1.23, 5.06, P = .012) during 5 years. CONCLUSION: An abnormal blood lipid profile in children is associated with the presence of atopic dermatitis and the SCORAD index. The risk of atopic dermatitis onset was significantly greater with high levels of TC.

Serum vitamin D level is associated with smell dysfunction independently of aeroallergen sensitization, nasal obstruction, and the presence of allergic rhinitis in children.

BACKGROUND: Smell dysfunction is highly prevalent worldwide and has adverse effects on quality of life. Smell loss in rhinitis subjects is mainly caused by mechanical obstruction of odorant transmission due to mucosal type 2 inflammation. We determined the association of 25-hydroxyvitamin D (25[OH]D) levels with the severity of smell dysfunction in children. METHODS: We measured the olfactory threshold score in a total of 518 children (10-12 years old, 264 boys) using the Sniffin' Sticks kit, and the children were divided into tertiles according to olfactory threshold score. We also assessed serum 25[OH]D level, common aeroallergen-specific immunoglobulin E, rhinitis severity with visual analog scale, and the Total Four Symptom Score, and pre- and post-decongestant nasal patency with acoustic rhinometry. RESULTS: The children with 25(OH)D deficiency had significantly reduced mean olfactory threshold scores when compared to those with 25(OH)D levels of ≥20.0 ng/mL (6.56 ± 3.54 and 7.28 ± 3.87, respectively, P = .036). The proportion of loss of smell function and pre-decongestant nasal patency significantly associated with low 25(OH)D levels (chi-square trend test, P for trend = .007). Likewise, after adjustment for confounders, children with smell loss (third tertile) were significantly associated with low 25(OH)D level (aß=-0.062, 95% CI=-0.064 to -0.060, P = .009) independent of aeroallergen sensitization, and a low pre-decongestant nasal patency. CONCLUSIONS: 25-Hydroxyvitamin D is significantly associated with smell dysfunction independent of aeroallergen sensitization, nasal obstruction, and the presence of allergic rhinitis. This finding may provide insight into the mechanisms involved in the development of olfactory dysfunction.

Assessment of vitamin D, exercise, and lipid profile associated with excessive daytime sleepiness in school children.

Previous research reported associations of excessive daytime sleepiness (EDS) with a low vitamin D level, obesity, and sexual maturity. The aim of this study was to identify the association and rank the importance of these with EDS. This study examined 618 children who were 10-12 year-old. The pediatric daytime sleepiness scale (PDSS) was used to evaluate EDS and sleep patterns. EDS was defined as a total PDSS score above 17. We ranked the importance of the relationship of these factors with EDS using random forest analysis. EDS (n = 111, 18%) was positively associated with more advanced pubertal stage in girls, chronic cough, urticaria, and allergic rhinitis. Multivariable analysis with adjustment for confounding indicated that children with low level of 25-hydroxyvitaminD3 (25(OH)D3 (<20 ng/mL) and high-density lipoprotein-cholesterol (HDL-C) (<40 mg/dL) levels had an increased risk of EDS (25(OH)D3:adjusted odds ratio [aOR] = 1.73; 95% confidence interval [CI]: 1.06 to 2.81; P = 0.028; HDL-C: aOR = 2.84; 95% CI: 1.05 to 7.68; P = 0.039). Random forest analysis indicated that 25(OH)D3 level, exercise, and body mass index (BMI) were over three. This study indicated high levels of 25-(OH)D3 and HDL-C and performing regular exercise decreased the risk of EDS.

Annual and seasonal patterns in etiologies of pediatric community-acquired pneumonia due to respiratory viruses and Mycoplasma pneumoniae requiring hospitalization in South Korea.

BACKGROUND: Community-acquired pneumonia (CAP) is one of the leading worldwide causes of childhood morbidity and mortality. Its disease burden varies by age and etiology and is time dependent. We aimed to investigate the annual and seasonal patterns in etiologies of pediatric CAP requiring hospitalization. METHODS: We conducted a retrospective study in 30,994 children (aged 0-18 years) with CAP between 2010 and 2015 at 23 nationwide hospitals in South Korea. Mycoplasma pneumoniae (MP) pneumonia was clinically classified as macrolide-sensitive MP, macrolide-less effective MP (MLEP), and macrolide-refractory MP (MRMP) based on fever duration after initiation of macrolide treatment, regardless of the results of in vitro macrolide sensitivity tests. RESULTS: MP and respiratory syncytial virus (RSV) were the two most commonly identified pathogens of CAP. With the two epidemics of MP pneumonia (2011 and 2015), the rates of clinical MLEP and MRMP pneumonia showed increasing trends of 36.4% of the total MP pneumonia. In children < 2 years of age, RSV (34.0%) was the most common cause of CAP, followed by MP (9.4%); however, MP was the most common cause of CAP in children aged 2-18 years of age (45.3%). Systemic corticosteroid was most commonly administered for MP pneumonia. The rate of hospitalization in intensive care units was the highest for RSV pneumonia, and ventilator care was most commonly needed in cases of adenovirus pneumonia. CONCLUSIONS: The present study provides fundamental data to establish public health policies to decrease the disease burden due to CAP and improve pediatric health.