Bladder cancer is associated with decreased urinary microbiota diversity and alterations in microbial community composition

Human urine microbiota (UM) research has uncovered associations between composition of microbial communities of the lower urinary tract and various disease states including several reports on the putative link between UM and bladder cancer (BC). The aim of this study was to investigate male UM in patients with BC and controls using catheterised urine specimens unlike in previous studies. Urine samples were obtained in theatre after surgical prepping and draping using aseptic catheterisation. DNA was extracted and hypervariable region V4 of the 16S rRNA gene was amplified using 515F and 806R primers. Sequencing was performed on Illumina MiSeq platform. Sequencing data were processed using appropriate software tools. Alpha diversity measures were calculated and compared between groups. Prevalence Interval for Microbiome Evaluation was used to test differences in beta diversity. A total of 63 samples were included in the analysis. Mean age of study subjects was 65.1 years (SD 12.5). Thirty-four men had bladder cancer and 29 participants were undergoing interventions for benign conditions (benign prostate hyperplasia or upper urinary tract stone disease). BC patients had lower UM richness and diversity than controls (83 vs. 139 operational taxonomic units, P = 0.015; Shannon index: 2.46 vs. 2.94, P = 0.049). There were specific taxa enriched in cancer (Veillonella, Varibaculum, Methylobacterium-Methylorubrum) and control groups (Pasteurella, Corynebacterium, Acinetobacter), respectively. BC patients had lower bladder microbiota richness and diversity than controls. Specific genera were enriched in cancer and control groups, respectively. These results corroborate some of previous reports while contradicting others. Future microbiota research would benefit from parallel transcriptomic/metabolomic analysis.