Abstract
INTRODUCTION: Little was known about the characteristics of low respiratory tract (LRT) microbiota of refractory M. pneumoniae pneumonia (RMPP) in children before and after the COVID-19 pandemic. METHODS: Forty-two children diagnosed with RMPP in 2019 (Y2019 group) and 33 children diagnosed with RMPP in 2023 (Y2023 group), entered into the study. The characteristics of the clinical findings were examined, and the LRT microbiota was analyzed by metagenomic next generation sequencing. RESULTS: The ratio of consolidate, atelectasis, lung necrosis, and erythema multiforme in Y2023 group was significantly higher than that in Y2019 (P<0.05). Mycoplasmoides pneumoniae was the top species of the LRT microbiota in both groups. The rate of macrolide resistance MP in Y2023 was significantly higher than that in Y2019 (P<0.05), and the mutant site was all 23S rRNA A2063G. There were no significant differences in α-diversity and β-diversity of LRT microbiota between Y2019 and Y2023 group. Trichoderma citrinoviride, Canine mastadenovirus A, Ralstonia pickettii, Lactococcus lactis, Pseudomonas aeruginosa were the biomarkers of LRT microbiota in children with RMPP of Y2023. The abundance of Mycoplasmoides pneumoniae positively correlated with the levels of D-dimer and LDH, negatively correlated with the counts of CD3(+) T cells, CD8(+) T cells, CD19(+) B cells and CD16(+)CD56(+) NK cells. DISCUSSION: Our study showed that high abundance of MP was correlated with the severity of RMPP and decrease of immune cells. Trichoderma citrinoviride, Canine mastadenovirus A, Ralstonia pickettii, Lactococcus lactis, Pseudomonas aeruginosa were the biomarkers in microbiota of LRT in children with RMPP post COVID-19 era.