Urinary microbiome in non-muscle invasive bladder cancer: impact of sample types and sex differences

Study information

Needs review

study design

cross-sectional observational, not case-control

Citation

PMID PubMed identifier for scientific articles.

41039241

DOI Digital object identifier for electronic documents.

https://doi.org/10.1186/s12866-025-04367-9

URI Uniform resource identifier for web resources.

Authors

Kang C., Lee J., Baek M.G., Kim N.E., Son H., Yoo S., Yi H.

Journal

BMC microbiology

Year

2025

Keywords:

Bladder cancer, Bladder microbiome, Catheterized urine, Curvibacter, Microbiome, Midstream urine, Mucosal tissue, Urinary microbiota

BACKGROUND: Previous research on urinary microbiomes in bladder cancer patients has yielded inconsistent results, highlighting the need for further investigation. This study aims to analyze microbiome dysbiosis in bladder cancer patients by comparing multiple sample types, incorporating negative controls, and assessing sex-based variations. Fifty patients who required transurethral resection of bladder tumor for treatment were selected. Three types of specimens were collected from each patient: midstream urine, catheterized urine, and normal bladder mucosal tissue. Microbiome was analyzed via 16 S rRNA gene amplificon sequencing. RESULTS: Beta diversity analysis revealed significant differences in microbiome composition between mucosal tissue and urine samples, while no significant variation was observed between midstream and catheterized urine samples. Due to the low biomass of mucosal tissue-characterized by dominance of a few taxa and high variability across extraction kit lots-its susceptibility to contamination compromised reproducibility, leading to a focus on urine samples for further analysis. Midstream urine samples showed significant sex-related microbiome differences, whereas catheterized urine exhibited no such differences, suggesting midstream urine may not be ideal for bladder-specific microbiome studies. Catheterized urine analysis identified Curvibacter, particularly Curvibacter gracilis, as significantly more abundant in bladder cancer patients compared to controls, while overall microbiome composition remained unchanged between the groups. Curvibacter prevalence was not directly correlated with any single clinical marker but increased with bladder cancer severity when patients were classified into high-risk and low-risk groups based on biopsy and clinical criteria. CONCLUSIONS: This study highlights the importance of selecting appropriate sample types for bladder microbiome analysis, with catheterized urine emerging as the most reliable option. The findings suggest that Curvibacter may be associated with bladder cancer severity, warranting further investigation into its potential role as a biomarker. Future research should focus on validating these findings in larger cohorts and exploring the mechanistic link between microbiome alterations and bladder cancer progression.

Experiment 1

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Needs review

Curated date: 2025/10/18

Curator: Susan githaiga

Revision editor(s): Susan githaiga, Tosin

Subjects

Location of subjects: South Korea

Host species Species from which microbiome was sampled. Contact us to have more species added.: Homo sapiens

Body site Anatomical site where microbial samples were extracted from according to the Uber Anatomy Ontology: Urine Urine,urine

Condition The experimental condition / phenotype studied according to the Experimental Factor Ontology: Urothelial carcinoma transitional cell car. -uroth.,transitional cell carcinoma of the urinary tract,transitional cell carcinoma of the urothelial tract,Uroepithelial carcinoma,urothelial carcinoma,Urothelial carcinoma

Group 0 name Corresponds to the control (unexposed) group for case-control studies: Non cancer controls with cancer-like symptoms (ETC)

Group 1 name Corresponds to the case (exposed) group for case-control studies: Urothelial carcinoma (UC)

Group 1 definition Diagnostic criteria applied to define the specific condition / phenotype represented in the case (exposed) group: Patients diagnosed with urothelial carcinoma of the bladder

Group 0 sample size Number of subjects in the control (unexposed) group: 13

Group 1 sample size Number of subjects in the case (exposed) group: 29

Lab analysis

Sequencing type: 16S

16S variable region One or more hypervariable region(s) of the bacterial 16S gene: V3-V4

Sequencing platform Manufacturer and experimental platform used for quantifying microbial abundance: Illumina

Statistical Analysis

Data transformation Data transformation applied to microbial abundance measurements prior to differential abundance testing (if any).: log transformation

Statistical test: Linear Regression; ANCOM-BC

Significance threshold p-value or FDR threshold used for differential abundance testing (if any): 0.05

MHT correction Have statistical tests be corrected for multiple hypothesis testing (MHT)?: Yes

Signature 1

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Needs review

Curated date: 2025/10/18

Curator: Susan githaiga

Revision editor(s): Susan githaiga

Source: Figure 3

Description: Volcano plot highlighting Curvibacter as the only genus significantly associated with urothelial carcinoma (UC) compared to non-cancer controls with cancer-like symptoms (ETC) (p < 0.05 and effect size >0.1).

Abundance in Group 1: increased abundance in Urothelial carcinoma (UC)

NCBI	Quality Control	Links
Curvibacter

Revision editor(s): Susan githaiga