Unravelling the origin of the seminal microbiome: comparative analysis of semen and urine samples before and after vasectomy

Abstract

The semen harbours a polymicrobial community; however, the origin of the seminal microbiome has not yet been clearly established. One-third of the seminal microbes originate from the urethra, whereas a considerable part could come from the upper genital tract. Similarly, male reproductive organs, such as the prostate, seminal vesicles, and testicles contain their own microbiome. Recent pioneering studies with a limited sample size indicate that the vasectomy procedure alters the seminal microbiome, suggesting a testicular or epididymal microbial origin. This cohort study included 82 men who were planning to undergo a vasectomy and provided paired semen and urine samples before and after this surgical procedure. The seminal microbiome was analysed by sequencing the V4 hypervariable region of the 16S rRNA gene. We found that vasectomy influences the seminal microbial composition and that the semen shares 50% of bacterial communities with urine, altogether indicating paracrine effects of the genitourinary system on the seminal microenvironment. Our study provides new insights into the origin of seminal microbes, suggesting that part of the seminal microbiome could originate from the testicular and urinary environment. Furthermore, we confirm the effect of the vasectomy procedure on seminal microenvironment, which could have a short- and long- term effect on male urogenital health.