The distribution characteristics of intestinal microbiota in children with community-acquired pneumonia under five Years of age.

Pneumonia is the leading cause of morbidity and mortality in children under five years of age worldwide. Over the past decades, studies have shown that the upper respiratory pathogens are closely related to the occurrence of pneumonia. However, the co-occurrence of gut microbiome dysbiosis may have clinical manifestation in the prognosis of childhood pneumonia. The aim of the present study is to investigate the differences in gut microbial communities between children's diagnosed community-acquired pneumonia (CAP) under five compared to healthy controls in Inner Mongolia. Fecal samples were collected from children with CAP and healthy controls (<5 years old) and the genomic microbiome 16S rRNA was amplified using the hypervariable V4 region and subjected to MiSeq Illumina sequencing, and then analyzed for microbiota composition and phenotype. Finally functional profiling was performed by KEGG pathways analyses. Our results revealed a gut microbiota dysbiosis in children with CAP. Distinct gut microbiome composition and structure were associated with childhood CAP between two age categories compared to healthy controls. In addition, the phylogenic phenotype's prediction was found to be significantly different between the groups. The prominent genera in age group of 0-3 were Bifidobacterium and Enterococcus. On the contrary, Escherichia-Shigella, Prevotella, Faecalibacterium and Enterobacter were remarkably decreased in most of the fecal samples from CAP patients in age group of 0-3 compared to the control. At the genus level, the CAP children in the age group of 4-5 showed an increase in the abundance of Escherichia/Shigella, Bifidobacterium, Streptococcus and Psychrobacter and, a decrease in the abundance of Faecalibacterium, Bacteroides, Lachnospiraceae and Ruminococcus compared with the matched healthy controls. Moreover, CAP children in both age groups exhibited distinct profiles in the KEGG functional analysis. Our data revealed that the gut microbiota differ between CAP patients and health children and certain gut microbial species are associated with CAP. Further research to identify specific microbial species which may contribute to the development CAP are merited. In addition, rectification of microbiota dysbiosis may provide supplemental benefits for treatment of the childhood CAP.