Network-Based Differences in the Vaginal and Bladder Microbial Communities Between Women With and Without Urgency Urinary Incontinence

Abstract

BackgroundLittle is known about the relationship of proximal urogenital microbiomes in the bladder and the vagina and how this contributes to bladder health. In this study, we use a microbial ecology and network framework to understand the dynamics of interactions/co-occurrences of bacteria in the bladder and vagina in women with and without urgency urinary incontinence (UUI).MethodsWe collected vaginal swabs and catheterized urine specimens from 20 women with UUI (cases) and 30 women without UUI (controls). We sequenced the V4 region of the bacterial 16S rRNA gene and evaluated using alpha and beta diversity metrics. We used microbial network analysis to detect interactions in the microbiome and the betweenness centrality measure to identify central bacteria in the microbial network. Bacteria exhibiting maximum betweenness centrality are considered central to the microbe-wide networks and likely maintain the overall microbial network structure.ResultsThere were no significant differences in the vaginal or bladder microbiomes between cases and controls using alpha and beta diversity. Silhouette metric analysis identified two distinct microbiome clusters in both the bladder and vagina. One cluster was dominated by Lactobacillus genus while the other was more diverse. Network-based analyses demonstrated that vaginal and bladder microbial networks were different between cases and controls. In the vagina, there were similar numbers of genera and subgroup clusters in each network for cases and controls. However, cases tend to have more unique bacterial co-occurrences. While Bacteroides and Lactobacillus were the central bacteria with the highest betweenness centrality in controls, Aerococcus had the highest centrality in cases and correlated with bacteria commonly associated with bacterial vaginosis. In the bladder, cases have less than half as many network clusters compared to controls. Lactobacillus was the central bacteria in both groups but associated with several known uropathogens in cases. The number of shared bacterial genera between the bladder and the vagina differed between cases and controls, with cases having larger overlap (43%) compared to controls (29%).ConclusionOur study shows overlaps in microbial communities of bladder and vagina, with higher overlap in cases. We also identified differences in the bacteria that are central to the overall community structure.

Influence of Vaginal Microbiota on Sexual and Reproductive Health: A Mini Review

“…Several studies have noted that a variety of vaginal microbial variations and the key bacteria concentrations are related to a higher risk of contracting HIV through several different potential pathways, including the yield of HIVinducing factors, inflammation [87], or by disrupting chemical and physical barriers to HIV [88]. Additionally, other vaginal infections including BV, which is marked by the presence of complicated anaerobic bacteria in the vagina, support HIV transmission [89]. Young South African women with very diversified vaginal microbial communities had an abundance of genital CD 4-positive T-cells that were activated, and as a result of recent investigation, they had four times the risk of contracting HIV than women with less diverse and L. crispatusdominant vaginal microbiomes [90].…”

Metabolic Syndrome and Overactive Bladder Syndrome May Share Common Pathophysiologies

“…Pearce et al found an increase in Gardnerella and a decrease in Lactobacillus in urinary microbiome were associated with female urgent urinary incontinence [ 73 ]. By using network analysis to study the microbiota between the vagina and bladder, Nardos et al pointed out a loss of diversity in urinary microbiota, which means the bladder bacterial genera are more likely to overlap with vagina bacterial genera, and this could be associated with female urgent urinary incontinence (43% in incontinent women vs. 29% in controls) [ 74 ].…”

“…Gut or urinary dysbiosis is one of the overlapping mechanisms between metabolic syndrome and overactive bladder. Gut flora can migrate to the urinary bladder via vagina colonization in women [ 74 ]. ( B ).…”

Cataloging the phylogenetic diversity of human bladder bacterial isolates

“…Previously, we published an analysis of 149 genomes of 78 different species isolated from the female bladder [14]. Several of the taxa found within the bladder microbiota are also inhabitants of the vaginal microbiota [14,21,22]. This led us to posit that the bacterial communities of these two anatomical sites may be connected [14].…”

“…This led us to posit that the bacterial communities of these two anatomical sites may be connected [14]. A recent 16S rRNA gene sequencing survey of paired bladder and vaginal samples identified more bacterial genera within the bladder than within the vagina, suggesting a greater bacterial diversity within the urinary tract [22]. In contrast, little overlap in species was reported between the microbiota of the urinary and gastrointestinal tracts [14], despite prior evidence that the gastrointestinal tract is the source of E. coli that cause urinary tract infections (UTIs) [23][24][25][26].…”