The microbiome of the infertile male

Purpose of review Contrary to historic dogma, many tissues and organs in the human body contain a resident population of bacteria, fungi, and viruses collectively known as the microbiome. The microbiome plays a role in both homeostatic symbiosis and also pathogenic dysbiosis in a wide array of diseases. Our understanding of the relationship between the microbiome and male factor infertility is in its infancy but is slowly evolving. Recent findings Recent literature indicates that semen (and likely the testis) is not sterile and contains a distinct microbiome, and these changes in its composition are associated with alterations in semen quality and fertility status. Preliminary investigation indicates that manipulating the human microbiome may have implications in improving semen parameters and fertility. Summary In this review, we describe relationships between the microbiome and the genitourinary system, discuss the prior work on the relationship among bacteriospermia, leukocytospermia and male factor infertility, and summarize the current literature utilizing 16s rRNA-based next-generation sequencing on the seminal and testicular microbiome. We explore the specific microbial taxa implicated in various aspects of spermatic dysfunction and introduce preliminary evidence for therapeutic approaches to alter the microbiome and improve fertility status.