Human Male Genital Tract Microbiota

Abstract

The human body is vastly colonised by microorganisms, whose impact on health is increasingly recognised. The human genital tract hosts a diverse microbiota, and an increasing number of studies on the male genital tract microbiota suggest that bacteria have a role in male infertility and pathological conditions, such as prostate cancer. Nevertheless, this research field remains understudied. The study of bacterial colonisation of the male genital tract is highly impacted by the invasive nature of sampling and the low abundance of the microbiota. Therefore, most studies relied on the analysis of semen microbiota to describe the colonisation of the male genital tract (MGT), which was thought to be sterile. The aim of this narrative review is to present the results of studies that used next-generation sequencing (NGS) to profile the bacterial colonisation patterns of different male genital tract anatomical compartments and critically highlight their findings and their weaknesses. Moreover, we identified potential research axes that may be crucial for our understanding of the male genital tract microbiota and its impact on male infertility and pathophysiology.

Metagenome-based microbial community analysis of urine-derived fertilizer

“…The metagenomic reads generated from our samples had low proportion (< 0.5%) of unassigned reads indicating the power of the annotation analysis. Members of the phyla Pseudomonadota (formerly Proteobacteria), Bacillota (Firmicutes) and Actinomycetota were reported to dominate freshly collected urine using 16SrRNA-based urine microbiome study by (Nelson et al, 2010; Zuber et al, 2023). No phylum-level change and higher OTU-counts (not statistically significant) was observed in the stored urine than that of the fresh urine.…”

“…Above all, these differences are better captured via applying nucleic acid-based methods (Jung et al, 2019). With the emergence of culture-independent approaches and the subsequent human microbiome project (Turnbaugh et al, 2007), studies revealed the presence of a unique microbiota in the urinary tract system (reviewed in Zuber et al, 2023), the microbial structure and composition is also reported to be subject to change with age, sex and health status (Halinski et al, 2023, Pearce et al, 2014). Next-Generation Sequencing (NGS) targeting 16S rRNA was the most widely used approach to determine the bacterial portion of the urinary microbiome (Perez-Carrasco et al, 2021, Siddiqui et al, 2011, Lahr et al, 2016).…”

Prostate and gut: Any relationship? A narrative review on the available evidence and putative mechanisms

“…Most of the studies performed so far have investigated the microbiota of the bladder or semen microbiome of post-massage urine in patients with pathologies such as PCa or infertility. 53,54 According to available evidence, seminal microbiota is associated with pathological states, such as viral infections (human immunodeficiency virus or human papillomavirus) or prostatitis. 53 A recent study demonstrated that symptoms of CP are associated with lesser microbial diversity of operational taxonomic units in semen and urine.…”

“…53,54 According to available evidence, seminal microbiota is associated with pathological states, such as viral infections (human immunodeficiency virus or human papillomavirus) or prostatitis. 53 A recent study demonstrated that symptoms of CP are associated with lesser microbial diversity of operational taxonomic units in semen and urine. 55 The proinflammatory effect of sperm dysbiosis is possible via the release of soluble factors, such as LPS, hemolysins, and other soluble spermatotoxic factors that can affect sperm physiology.…”

“…The clinical effects of sperm dysbiosis comprise reduction in motility, induction of teratozoospermia (i.e., abnormal sperm morphology), apoptosis, DNA fragmentation, sperm agglutination, and exposure to oxidative stress through the formation of reactive oxygen species. 53 Hence, pathogenic bacteria in seminal fluid is a well-recognized trigger of local immune reaction and is likely to be a promoter of carcinogenesis.…”