The discovery of a resident urinary microbiome has challenged the long-standing view of the bladder as sterile. Overactive bladder (OAB), a common and burdensome condition, has been linked to urinary dysbiosis, yet the origins of bladder colonization and its relationship to adjacent microbiomes remain unclear.
to compare the urinary microbiome profiles of women with OAB to those of healthy controls, to assess intra-individual relationships between the urinary and other urogenital or mucosal microbiomes-including the vaginal, urethral, buccal sites and stool-and to identify potential colonization pathways by analyzing microbial overlap within and between individuals.
In a cross-sectional study, we profiled the microbiomes of 50 women with OAB and 49 healthy controls across urine, urethra, vagina, oral cavity and stool. DNA was extracted using standardized protocols and the V3-V4 region of the 16S rRNA gene was sequenced on the Illumina MiSeq platform. Reads were processed with DADA2 and taxonomically classified using the SILVA database. Diversity metrics (alpha and beta diversity), differential abundance testing (DESeq2), and cross-site microbial overlap analyses were performed in R using established packages (phyloseq, vegan, mia, microViz). Subgroup analyses accounted for menopausal status.
OAB cases exhibited higher alpha diversity in urethral and vaginal samples and significantly different beta diversity across all sites compared with controls (p < 0.004). The urethra of OAB cases contained reduced Lactobacillus but was enriched with Bacteroides, Bifidobacterium, Gardnerella, Hydrotalea, Streptococcus, and other genera. Six taxa (Alistipes, Bacteroides, Bifidobacterium, Bradyrhizobium, Hydrotalea, Neisseria) consistently met thresholds for abundance and prevalence in urethra and were also elevated in OAB urine, vagina, and oral cavity, but not stool. Intra-individual analyses showed greater urethra-urine and urethra-vagina divergence in OAB than in controls, indicating disruption of the normal microbial continuum. Subgroup analyses confirmed between-group differences irrespective of menopausal status. Notably, dysbiosis in OAB overrode the pre/postmenopausal contrasts observed in controls.
Women with OAB seem to have a distinct multi-site dysbiosis, most pronounced in the urogenital tract, characterized by loss of Lactobacillus and enrichment of select taxa across urethra, urine, vagina, and oral cavity. The observed microbial overlap across urogenital sites, compared with stool, is consistent with predominant urogenital microbial relatedness in this cross-sectional cohort. These findings provide insight into microbiome alterations in OAB and highlight the need for longitudinal studies to clarify mechanisms and evaluate potential microbiome targeted strategies. Given the cross-sectional design, these findings describe associations and cannot establish causality or the directionality of microbial transmission between compartments.
American journal of obstetrics and gynecology. 2026 Feb 17 [Epub ahead of print]
Marianne Koch, Wolfgang Umek, Athanasios Makristathis, Bela Hausmann, Barbara Bodner-Adler, Ksenia Krögler-Halpern, Anika Dibon, Rosa Loimer, Rebecca Bauer, F Heinzl, Greta Carlin
Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria; Karl Landsteiner Institute of special gynaecology and obstetrics. Electronic address: ., Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria; Karl Landsteiner Institute of special gynaecology and obstetrics., Department of Laboratory Medicine, Division of Clinical Microbiology, Medical University of Vienna; Vienna, Austria; Joint Microbiome Facility (JMF) of the University of Vienna and the Medical University of Vienna, Vienna, Austria., Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria.