In a recent study published in Scientific Reports, researchers analyzed the connection between semen microbiota and changes in semen parameters.
Study: Semen microbiota are dramatically altered in men with abnormal sperm parameters. Image Credit: KateStudio/Shutterstock.com
Male infertility has been increasing and will not be fully understood despite scientific and research advances. The etiology of abnormal parameters in semen evaluation (SA) is unknown in nearly a 3rd of cases.
The microbiome has been implicated in human health and disease, and analyses have been prolonged to explore the semen microbiome and its role in male infertility.
Only a couple of studies have assessed the semen microbiome, and even fewer have explored it within the context of fertility.
One study examined the semen microbiome profile and highlighted the differences in alpha and beta diversity between infertile males and healthy controls; furthermore, the study revealed an association between total motile sperm count and the genus Pseudomonas.
One other study reported that males with non-obstructive azoospermia had changes within the beta diversity of the semen microbiome in comparison with healthy controls.
In regards to the study
In the current study, researchers examined the connection between the semen microbiome and changes in SA parameters.
Adult males (≥ 18 years) presenting for a fertility evaluation and people with biological paternity before vasectomy were recruited between August 2021 and June 2022. Data on age, circumcision, body mass index (BMI), alcohol use, and smoking status were collected.
Participants provided semen samples after two to seven days of abstinence. Samples were collected before pharmacological or surgical interventions for fertility.
A calibrated automated semen analyzer was used to guage semen. High-powered microscopy was used to look at samples with azoospermia or oligozoospermia. The overall motile sperm count was estimated.
Semen pH, volume, motility, strict morphology, and concentration were determined. DNA extraction, amplification, and sequencing of 16S ribosomal RNA (rRNA) V1-V2 regions were performed.
Bioinformatic curation, quality control, and data analyses were performed. Bacterial community coverage was estimated using the Good’s coverage formula.
Alpha diversity was estimated using the Hill1 diversity, phylogenetic hill1 diversity, and operational taxonomic unit (OTU) richness indices. Beta diversity was assessed by weighted UniFrac distances and clustered qualitatively using principal coordinate evaluation (PCoA).
Samples were classified as normal or abnormal based on SA results. Canonical correlation evaluation measured the association between participant metadata and the relative abundance of species.
Overall, 73 males aged 37.94 with a BMI of 26.73, on average, were included. Around 78% of them were circumcised. Participants were stratified into three groups: 1) normal sperm motility and concentration, 2) normal sperm motility, and three) normal sperm concentration.
There have been no differences in BMI, age, circumcision status, alcohol intake, or smoking history amongst groups. Participants recruited during fertility evaluation were sexually lively.
Sexual intercourse was unknown for those recruited before vasectomy. Alpha or beta diversity was not significantly different amongst groups. Bacterial communities were similar when evaluated using PCoA with weighted UniFrac distances.
Further, essentially the most abundant species were overlapped considerably. Corynebacterium tuberculostearicum, Enterococcus faecalis, Finegoldia magna, Lactobacillus iners, and Staphylococcus epidermis were all the time the highest five species.
Evaluation of microbiota composition with bias correction revealed that individuals with normal parameters on SA (group 1) had the next abundance of S. hominis but a lower abundance of Peptoniphilus coxii than participants with not less than one abnormality in SA.
Individuals with normal sperm motility (group 2) had a reduced abundance of L. iners in comparison with those with abnormal motility.
The abundance of Pseudomonas stutzeri, Paraburkholderia phenazinium, and Pseudomonas fluorescens was lower within the third group. At the identical time, that of Pseudomonas putida was higher in males with normal sperm concentration than those with abnormal concentration.
Participants’ age, semen volume, sperm motility, and concentration were significantly related to the composition of bacteria.
The findings suggest that a subset of microbes has a task in altered SA parameters. L. iners strongly differentiated males with normal SA parameters from those with abnormal parameters.
L. iners was particularly enriched within the semen microbiota of males with abnormal sperm motility.
While prior studies indicate a negative role for this species in fertility, most studies were related to female aspects and vaginal microbiome.
The findings suggest that a small subset of microbes could have a critical role in male fertility. While the outcomes don’t indicate causality, they could inform future studies to delineate the connection between semen microbiota and fertility.