Structure and diversity of the urinary microbiota in relation to gender and age: a cohort study with 1,172 Chinese adults

Background: A complex microbial community exists in the human urinary tract, with significant roles in chronic and infectious diseases. The microbial composition of urine can vary with gender, age, geography and other host properties, yet there lacks a comprehensive profiling of the urinary microbiota in a relatively large healthy cohort. Results: In this study, we profiled the urinary microbial communities of 1,172 healthy adults using 16S rRNA gene sequencing of midstream urine specimens. The core microbiota of urine consisted of 6 dominant genera (mean relative abundance >5%) and 131 low-abundance genera (mean relative abundance 0.01-5%), which displayed a distinct overall structure to that of host-matched gut microbiota. Driving by the abundance of dominant microbes, urinary microbiota was stratified into 7 urotypes with different microbial compositions and functions. Interestingly, the low-abundance genera harbored a variety of specific functions and maintained extensive interspecies networks. Moreover, we revealed that the individuals’ gender and age, two main factors of the urinary microbiota variances, had a large impact on the microbial diversity, structure and urotype; while the gender- and age-associated differences were interdependent. Urinary microbiota-based models also showed high performance in predicting host’s gender and age. Conclusions: Our results delineated the microbial structure and diversity landscape of urinary microbiota in healthy adults and provided insights into the influence of gender and age.