Gut microbiota in preterm infants with late-onset sepsis and pneumonia：A pilot case-control study

Abstract Background: Late-onset sepsis (LOS) and pneumonia are common infectious diseases, with high morbidity and mortality in neonates. This study aims to investigate the differences in intestinal microbiota among preterm infants with LOS, or pneumonia, and full-term infants. Furthermore, this study intends to determine whether there is a correlation between intestinal pathogenic colonization and LOS. Methods: In a single-center case-control study, 16S rRNA gene sequencing technology was used to compare intestinal flora characteristics and differences among LOS group, pneumonia group, and control group. Results: It was found that gut microbiota in control group showed higher diversity compared with LOS group and pneumonia group (P＜0.05) . Moreover, a similar diversity between LOS group and pneumonia group could be observed (P> 0.05). The pathogenic bacteria of LOS in infants were consistent with the distribution of the main bacteria in the intestinal flora. Through metastases analysis and Linear discriminant analysis Effect Size (LEfSe), we identified a significant association between LOS and specific bacterial changes. Compared with the control group, Akkermansia, Escherichia/Shigella, and Enterococcus increased, while Bacteroides and Stenotrophomonas decreased in the LOS and pneumonia group. The increase of Escherichia/Shigella abundance could predict the occurrence of LOS, with an area under the curve (AUC) of 0.773. Conclusion: Dominant bacteria in intestinal flora of LOS group were associated with the causative pathogen of LOS. The increase of Escherichia/Shigella, Akkermansia, Enterococcus, and the decrease of Bacteroides, showed potential correlation between intestinal flora and LOS, pneumonia. Furthermore, preterm infants with an increased abundance of Escherichia/Shigella can be regarded as potential candidates for predicting the occurrence of LOS.