The urobiome of continent adult women: a cross-sectional study

Abstract

Objective: To characterise the bladder microbiota of continent adult women.

Design: Cross-sectional study of adult women who contributed catheterised urine samples, completed validated symptom questionnaires, and provided demographic data.

Setting: US academic medical centre.

Population: Well-characterised continent adult women.

Methods: Participants contributed symptoms questionnaires, demographic data, and catheterised urine samples that were analysed by enhanced urine culture methodology and 16S rRNA gene sequencing.

Main outcome measures: Associations between demographics and microbial community state structures (urotypes, defined by the dominant taxon of each specimen).

Results: The bladder microbiota (urobiome) of a control group of 224 continent women were characterised, demonstrating variability in terms of urotype. The most common urotype was Lactobacillus (19%), which did not differ with any demographic. In contrast, the Gardnerella (P < 0.001) and Escherichia (P = 0.005) urotypes were more common in younger and older women, respectively.

Conclusions: For urobiome research, enhanced culture methods and/or DNA sequencing are the preferred techniques for bacterial detection. The interpretation of clinical tests, such as the standard urine culture, should incorporate the knowledge that some women have Gardnerella or Escherichia urotypes without evidence of any clinical disorder. Clinical care strategies should preserve or restore the beneficial effects of the native urobiome, as disruption of that microbial community could result in unintended vulnerability to uropathogen invasion or opportunistic pathogen overgrowth. Longitudinal studies of urobiome responses to therapies should be encouraged.

Tweetable abstract: In continent adult women bladder microbiome composition differs by age, with relevance for clinical practice.

Keywords: Bladder health; female bladder; urinary microbiome; urinary microbiota; urobiome.

Figure 1.. Urinary Microbiota Assessed by EQUC and 16S rRNA Sequencing.

(A) Microbiota profiles are shown as stacked bar graphs depicting the relative abundance (y-axes) of various taxa from each participant (x-axes). Data were obtained using EQUC (top) and 16S rRNA gene sequencing (bottom). EQUC-obtained data were sorted using hierarchical clustering of the the Euclidean distance between samples (dendrogram). Subsequently, the data obtained by 16S rRNA gene sequencing were sorted according to the EQUC data. A legend containing the most common taxa is shown on the left. ‘Other’ refers to the combined relative abundance for all taxa not included in the 20 most abundant taxa obtained by 16S rRNA gene sequencing. Note that the genera Escherichia (gold) and Gardnerella (maroon) are members of the families Enterobacteriaceae (yellow) and Bifidobacteriaceae (pink), respectively. (B) Species accumulation curve of the bacterial species culture and identified by EQUC.

Figure 2.. Comparison of EQUC and 16S rRNA Gene Sequencing Data.

Comparison of taxa detected by EQUC and 16S rRNA gene sequencing. (A) Comparison of EQUC and sequence status. (B) Comparison of the urotypes determined by EQUC and sequencing. Urotypes were assigned based on the presence of a taxa at >50% relative abundance. Numbers depict the number of urine specimens with the corresponding urotypes. Cells in red indicate that the two methods did not match; cells in green indicated that the two methods matched.

Figure 3.. EQUC Urotype by Age Distribution.

Box plots depict the range of ages of the participants according to EQUC urotype. Median scores are depicted by the solid lines in each box.