Overactive bladder (OAB) and bladder pain syndrome/interstitial cystitis (BPS/IC) are common, multifactorial conditions whose underlying biology has remained elusive. The review highlights mounting evidence that bladder microbial communities can influence urothelial signaling, calibrate immune tone, and modulate neural pathways involved in urgency and nociception.

For OAB, studies summarized in the article point to community-level signatures rather than single pathogens. Urinary profiles enriched for Lactobacillus are associated with lower symptom burden and better responsiveness to standard pharmacotherapy. By contrast, Gardnerella-enriched and Pseudomonadota-enriched communities correlate with refractory disease, suggesting that microbiome composition may mark distinct disease trajectories.

Mechanistically, the authors emphasize that microbial metabolites and epithelial interactions may drive changes in barrier integrity and inflammatory signaling. Such effects could alter afferent signaling to the spinal cord, thereby increasing perceived urgency and sustaining symptoms even when conventional treatments underperform.

BPS/IC appears more complex: microbial alterations do not converge on a single “pathogenic” organism. Instead, dysbiosis is linked to overlapping disturbances in metabolic and immune pathways, implying that function may matter more than identity. The review notes that low-biomass sampling and contamination control remain critical for drawing reliable conclusions.

To move beyond correlation, the paper discusses multi-omics strategies that integrate metagenomics, metabolomics, and host immune profiling. These approaches aim to connect microbial metabolic outputs to epithelial dysfunction and nociceptor sensitization—two processes thought to underlie chronic bladder pain.

Emerging clinical trial data discussed by the authors suggest a translational path: microbiome profiling could help stratify patients likely to benefit from specific therapies. In parallel, microbiome-targeted interventions—including probiotics, estrogen-based treatments, and dietary modulation—are presented as potential adjuncts that may reshape the urinary environment.

Despite the promise, the review underscores a core unresolved problem: whether the low-biomass urinary microbiome plays a causal role or mainly reflects disease-associated changes in the bladder ecosystem. Establishing causality will require carefully designed longitudinal studies and intervention trials that measure functional outcomes.

Ultimately, the urinary microbiome is positioned as both a potential diagnostic lever and a candidate therapeutic target, bringing precision urology closer to biology-driven treatment selection while highlighting the need for rigorous validation.

Subject of Research: Lower urinary tract disorders; urinary microbiome; overactive bladder; bladder pain syndrome/interstitial cystitis.
Article Title: The urinary microbiome, overactive bladder and bladder pain syndrome/interstitial cystitis — mechanisms, diagnostics and therapeutic opportunities.
Article References: Spazzapan, M., Raison, N., Steves, C. et al. The urinary microbiome, overactive bladder and bladder pain syndrome/interstitial cystitis — mechanisms, diagnostics and therapeutic opportunities. Nat Rev Urol (2026). https://doi.org/10.1038/s41585-026-01174-3
Image Credits: AI Generated
DOI: 10.1038/s41585-026-01174-3
Keywords: urinary microbiome; overactive bladder; bladder pain syndrome/interstitial cystitis; Lactobacillus; Gardnerella; Pseudomonadota; multi-omics; precision urology; probiotics; estrogen therapy; metabolomics