Interplay between bladder microbiota and overactive bladder symptom severity: a cross-sectional study

It is widely accepted that there exist microbiota communities in urinary tract of healthy individuals. Imbalance in the urinary microbiome plays important roles in the development of various benign urological conditions including lower urinary track symptoms (LUTS) and overactive bladder (OAB). However, whether alteration in urinary microbiome exerts influence on the severity of OAB symptom has yet to be elucidated. The purpose of this study is to examine the correlation between urinary microbiome and the severity of OAB.

A total of 70 OAB patients were recruited to finish overactive bladder symptom score (OABSS) questionnaires. Catheterized urine samples were obtained for 16S rRNA gene sequencing. The species richness and evenness were evaluated by α diversity, and the difference in urinary microbiome between patients with mild or moderate/severe severity was evaluated by β diversity. The relationship between urinary microbiome and the severity of OAB symptom was evaluated using Pearson's correlation analysis.

Mild patients (OABSS ≤ 5, n = 17) had lower bacterial diversity (Simpson index, P = 0.024) and richness (Chao1, P = 0.023) than those with moderate/severe symptom (OABSS > 5, n = 53). Beta-diversity of urinary microbiome between two groups were significantly different. Furthermore, the score of OABSS was positively correlated with the richness index (Chao1, P = 0.002) and diversity index (Shannon index, P = 0.044) of urinary microbiome. Certain bacterial genera (e.g., Porphyromona and Prevotella) were significantly correlated with severity of OAB sub-symptoms.

This study demonstrated that urinary microbiome was intimately correlated with the severity of OAB symptom and the increase of the diversity and richness of urinary microbiome was accompanied by more severe OAB symptoms, indicating that urinary dysbiosis may play pivotal roles in the deterioration of functional bladder diseases.