Introduction: Respiratory infection in particular community acquired pneumonia (CAP) in children is a major disease that ranks high in outpatient and inpatient cases. The causes of CAP vary depending on the individual susceptibility, epidemiological characteristics of the community, and season. We performed this study to establish nationwide survillance network system and identify the causative agents for CAP and antibiotics resistance in Korean children with CAP.. Methods: The monitoring network was composed of the 28 secondary and tertiary medical institutions. Upper and lower respiratory samples were assayed using culture or Polymerase chaini reaction (PCR) from Aug 2018 to May 2020. Results: A total of 1023 cases were registered in patients with CAP, and 264 cases (25.8%) were isolated by culture, S. aureus 131 cases (12.8%), S. pneumoniae 92 cases (9%), H. influenzae 20 cases (2%). PCR of atypical pneumonia pathogen revealed 422 cases of M. pneumoniae (41.3%). Respiratory virus showed positive rates in 65.7% by multiplex PCR test and of them, human rhinovirus was most highest with 312 cases (30.5%). The proportion of mixed infection was 49.2%. The rate of antibiotics resistance showed similar results as previous reports. Conclusion: It 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 infection. Also, in preparation for the new epidemic, including COVID19, monitoring of respiratory infections in children and adolescents, has become more important, and research should be continuously conducted in the future.

Background: The role of the gut microbiome in the onset and development of atopic dermatitis (AD) has been postulated. Therefore, we investigated the gut microbial compositions in infants with and without AD, and compared it to the gut bacterial flora of their mothers. Methods: This was a prospective and cross-sectional study. Among 44 pairs of mothers and children, we selected infants who were born via full-term normal vaginal delivery and that had 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 of age. Microbes in the fecal samples of mothers and infants were subjected to analysis of 16S rRNA amplicon sequencing. Results: 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. Conclusions: These data indicated that the presence of Akkermansia muciniphila in mothers and children after vaginal delivery is associated with the onset and development of AD.