Alterations in the Urinary Microbiota Are Associated With Cesarean Delivery

Abstract

Similar to the gut, the bladder contains urinary microbiota, and its bacterial composition and structure are determined by the individual's health status. Cesarean section is a traumatic event for women and it is correlated with postpartum complications. To better understand the urinary microbiota alterations caused by cesarean section, 16S rDNA sequencing was used to assess urine specimens collected by transurethral catheterization from 30 healthy women undergoing cesarean section pre-delivery (PreD) and post-delivery (PostD). A significant increase in bacterial diversity and more detectable bacteria at the phylum, family, and genus levels was observed in the PostD group compared to the PreD group, indicating that cesarean delivery (a process that includes surgery and delivery) altered the bacterial community. Specifically, the phylum Firmicutes and its affiliated family Lactobacillaceae and genus Lactobacillus dramatically decreased in the PostD group, suggesting that beneficial bacteria decreased after cesarean section, and clinicians should be aware that this might increase the risk of complications. Concurrently, the phylum Proteobacteria and its affiliated bacteria Pseudomonadaceae and Pseudomonas increased in the PostD group compared to the PreD group. This indicates that pathogen growth increases after cesarean section, making it important for clinicians to combat these changes to protect women from infectious diseases. Interestingly, several metabolic pathways, such as metabolism of energy, cofactors and vitamins were strengthened in the PostD group, whereas membrane transport was lessened in this group. This suggests that women's metabolic disorders might be cured by balancing urinary microbiota. In conclusion, the altered urinary microbiota between the PreD and PostD periods appears to provide insight into how to prevent postpartum metabolic disorders.

Keywords: Lactobacillus; Proteobacteria; cesarean section; delivery; urinary microbiota.

FIGURE 1

Bacterial diversity. (A) Good’s coverage was used to assess sequencing depth. (B) The Chao 1 index was used to measure richness, and the Shannon and Simpson rarefaction indices were applied to estimate diversity. ^∗Indicates that a significant difference was found between groups (p < 0.05). (C) Venn diagram showing the number of OTUs shared between the PreD and PostD groups. (D) Principal coordinates analysis plot of the urinary microbiota based on the unweighted UniFrac metric. Blue and red dots represent the PostD and PreD groups, respectively. PreD means pre-delivery and PostD means post-delivery.

FIGURE 2

Taxonomic visualization. Taxonomic tree visualized using GraPhlAn. The color of each node is consistent with the color of the corresponding bacterial phylum node located in the upper left corner of the graph. Each letter in the inner circle is consistent with the letter located in the upper right corner of the graph. The orange and blue columns around the circle represent the relative abundances of bacterial families in the PreD and PostD groups, respectively. PreD means pre-delivery and PostD means post-delivery.

FIGURE 3

Bacterial genera profile. Top 10 most abundant bacterial genera in the PreD and PostD groups. PreD means pre-delivery and PostD means post-delivery.

FIGURE 4

Bacterial genera differences. Bacterial genera showing significant differences in relative abundance between the PreD and PostD groups. PreD means pre-delivery and PostD means post-delivery.

FIGURE 5

Contributions of OTUs to known biological metabolic pathways. Functional analysis of urinary microbiota from the PreD and PostD groups. Microbial pathways predicted to be differentially regulated based on microbiome differences between the PreD (orange) and PostD (blue) groups. Upregulated pathways are represented by a higher mean proportion of expression. q-values are based on White’s nonparametric t-test and corrected using the Story false discovery rate-controlling procedure.