Sperm Microbiota and Its Impact on Semen Parameters

Seminal and vagino-uterine microbiome and their individual and interactive effects on cattle fertility

Reproductive failure is a major economical drain on cow-calf operations across the globe. It can occur in both males and females and stem from prenatal and postnatal influences. Therefore, the cattle industry has been making efforts to improve fertility and the pregnancy rate in cattle herds as an attempt to maintain sustainability and profitability of cattle production. Despite the advancements made in genetic selection, nutrition, and the implementation of various reproductive technologies, fertility rates have not significantly improved in the past 50 years. This signifies a missing factor or factors in current reproductive management practices that influence successful fertilization and pregnancy. Emerging lines of evidence derived from human and other animals including cattle suggest that the microbial continuum along the male and female reproductive tracts are associated with male and female fertility-that is, fertilization, implantation, and pregnancy success-highlighting the potential for harnessing the male and female reproductive microbiome to improve fertility in cattle. The objective of this narrative review is to provide an overview of the recent studies on the bovine seminal and vagino-uterine microbiome and discuss individual and interactive roles of these microbial communities in defining cattle fertility.

Semen dysbiosis—just a male problem?

Seminal microflora is crucial to male fertility. Dysbiosis—disturbance of quantitative ratios of individual bacteria or appearance of pathogenic species—rarely results in symptomatic disease. Inflammation results in decreased sperm production, lower motility, or morphological changes and, in the long term, can cause ejaculatory duct obstruction, leading to infertility. Moreover, it may cause infection of the partner’s female genital tract. Dysbiosis in both partners results in fertility problems, disorders in embryo implantation, or miscarriages. In addition, chronic inflammation of the male genitourinary system may accelerate the appearance of antisperm antibodies. A comprehensive examination of seminal microflora can clarify the causes of infertility or prevent pathological conditions that affect seminal parameters. Seminal microflora as a direct impact on fertility problems as well as a decrease in the effectiveness of assisted reproduction methods, insemination, or in vitro procedures.

Bacteriospermia - A formidable player in male subfertility

Bacterial colonization of male reproductive tissues, cells, and fluids, and the subsequent impact of bacteria on the sperm architecture, activity, and fertilizing potential, has recently gained increased attention from the medical and scientific community. Current evidence strongly emphasizes the fact that the presence of bacteria in semen may have dire consequences on the resulting male fertility. Nevertheless, the molecular basis underlying bacteriospermia-associated suboptimal semen quality is sophisticated, multifactorial, and still needs further understanding. Bacterial adhesion and subsequent sperm agglutination and immobilization represent the most direct pathway of sperm-bacterial interactions. Furthermore, the release of bacterial toxins and leukocytic infiltration, associated with a massive outburst of reactive oxygen species, have been repeatedly associated with sperm dysfunction in bacteria-infested semen. This review serves as a summary of the present knowledge on bacteriospermia-associated male subfertility. Furthermore, we strived to outline the currently available methods for assessing bacterial profiles in semen and to outline the most promising strategies for the prevention and/or management of bacteriospermia in practice.

Diagnosis of bacteriospermia and its impact on spermogram parameters in adolescents with varicocele

Infectious etiology is the cause of about 15% of cases of male infertility. And if sexually transmitted infections are easily diagnosed, the role of asymptomatic bacteriospermia in the formation of infertility in men, and especially in adolescents against the background of the existing pathology of the reproductive sphere (varicocele), remains insufficiently studied. A microbiological study in the ejaculate of adolescents revealed the following types of bacteria: Escherichia coli, Enterococcus faecalis, Corynebacterium glucuronolyticum, Corynebacterium minitissimum, Streptococcus anginosus, Staphylococcus epidermidis, Staphylococcus haemolyticus. Bacteria in the ejaculate were also detected during semen analysis and electron microscopic examination of spermatozoa. With abundant growth of microorganisms in a monoculture or an association of two microorganisms present in a moderate amount, in all cases, violations of sperm motility, an increase in the viscosity of the ejaculate, the presence of leukocytes in the seminal fluid were detected, and damage to the chromatin, acrosome and mitochondria was recorded at the ultrastructural level, which may indicate active infection. When bacterial flora was detected in a small and moderate amount (<10 CFU/ml), no pathological changes in the ejaculate were observed. The microflora of the ejaculate of the examined adolescents is represented by gram-positive microflora. Simultaneous study of the ejaculate sample by bacteriological seeding, the performance of spermogram and EMIS allowed to increase the detection of bacteriospermia. Opportunistic pathogens with abundant growth or their various combinations can serve as a factor in the development of pathospermia. It is possible to distinguish an active infection from commensal microflora or sample contamination not only by the presence of bacteria in the ejaculate and their quantitative accounting, but also by the degree of damage to the function of spermatozoa and pathological changes in the parameters of the ejaculate, by combining diagnostic methods. Most often, in the presence of bacteria in the ejaculate, asthenozoospermia is diagnosed.

Tenets in Microbial Endocrinology: A New Vista in Teleost Reproduction

Climate vulnerability and induced changes in physico-chemical properties of aquatic environment can bring impairment in metabolism, physiology and reproduction in teleost. Variation in environmental stimuli mainly acts on reproduction by interfering with steroidogenesis, gametogenesis and embryogenesis. The control on reproductive function in captivity is essential for the sustainability of aquaculture production. There are more than 3,000 teleost species across the globe having commercial importance; however, adequate quality and quantity of seed production have been the biggest bottleneck. Probiotics are widely used in aquaculture as a growth promoter, stress tolerance, pathogen inhibition, nutrient digestibility and metabolism, reproductive performance and gamete quality. As the gut microbiota exerts various effects on the intestinal milieu which influences distant organs and pathways, therefore it is considered to be a full-fledged endocrine organ. Researches on Gut-Brain-Gonad axis (GBG axis) and its importance on physiology and reproduction have already been highlighted for higher mammals; however, the study on fish physiology and reproduction is limited. While looking into the paucity of information, we have attempted to review the present status of microbiome and its interaction between the brain and gut. This review will address a process of the microbiome physiological mechanism involved in fish reproduction. The gut microbiota influences the BPG axis through a wide variety of compounds, including neuropeptides, neurotransmitter homologs and transmitters. Currently, research is being conducted to determine the precise process by which gut microbial composition influences brain function in fish. The gut-brain bidirectional interaction can influence brain biochemistry such as GABA, serotonin and tryptophan metabolites which play significant roles in CNS regulation. This review summarizes the fact, how microbes from gut, skin and other parts of the body influence fish reproduction through the Gut-Brain-Gonad axis.

A Retrospective Narrative Mini-Review Regarding the Seminal Microbiota in Infertile Male

Background: Infertility is a global burden that affects both sexes with the male component remaining as an explored yet crucial research field that might offer novel evidence. Material and Methods: The present narrative mini-review aims to summarize all existing literature regarding the composition of the seminal microflora in infertile men. We performed searches in PubMed/Medline, ISI Web of Knowledge, Scopus, and ScienceDirect between 2018 and 2022 using a combination of keywords. Results: A total of n = 33 studies met the eligibility criteria and were further considered. From this, n = 14 were conducted on human patients, n = 3 on zebrafish (Danio rerio), n = 5 on rats, and n = 11 on mice. In twenty-five out of thirty-three papers, the authors sequenced the 16S rRNA; situations occurred where researchers focused on standard laboratory protocols. Lactobacillus and Bifidobacterium are widely recognized as putative beneficial lactic bacteria. These two entities are capable of restoring the host's eubiosis to some extent, blocking pathogens' proliferation and endotoxins, and even alleviating specific patterns encountered in disease(s) (e.g., obesity, type 1 diabetes) due to prolonged exposure to toxicants in adults or from a developmental stage. Over the years, distinct approaches have been perfected, such as the transfer of feces between two species or conventional rudimentary products with proven efficiency. Conclusions: The seminal microflora is decisive and able to modulate psychological and physiological responses. Each individual possesses a personalized microbial profile further shaped by exogenous factors, regardless of sex and species.

Possible Implications of Bacteriospermia on the Sperm Quality, Oxidative Characteristics, and Seminal Cytokine Network in Normozoospermic Men

This study focused on the identification of bacterial profiles of semen in normozoospermic men and their possible involvement in changes to the sperm structural integrity and functional activity. Furthermore, we studied possible fluctuations of selected cytokines, oxidative markers, and antibacterial proteins as a result of bacterial presence in the ejaculate. Sperm motility was assessed with computer-assisted sperm analysis, while sperm apoptosis, necrosis and acrosome integrity were examined with fluorescent methods. Reactive oxygen species (ROS) generation was quantified via luminometry, sperm DNA fragmentation was evaluated using the TUNEL protocol and chromatin-dispersion test, while the JC-1 assay was applied to evaluate the mitochondrial membrane potential. Cytokine levels were quantified with the biochip assay, whilst selected antibacterial proteins were quantified using the ELISA method. The predominant species identified by the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were Staphylococcus hominis, Staphylococcus capitis and Micrococcus luteus. The results revealed that the sperm quality decreased proportionally to the increasing bacterial load and occurrence of conditionally pathogenic bacteria, including Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. Antimicrobial susceptibility tests revealed a substantial resistance of randomly selected bacterial strains to ampicillin, vancomycin, tobramycin, and tetracycline. Furthermore, an increased bacterial quantity in semen was accompanied by elevated levels of pro-inflammatory cytokines, including interleukin-1, interleukin-2, interleukin-6, tumor necrosis factor alpha as well as ROS overproduction and lipid peroxidation of the sperm membranes. Our results suggest that semen quality may be notably affected by the bacterial quantity as well as quality. It seems that bacteriospermia may be associated with inflammatory processes, oxidative stress, sperm structural deterioration, and a subsequent risk for the development of subfertility, even in normozoospermic males.

Paternal transgenerational nutritional epigenetic effect: A new insight into nutritional manipulation to reduce the use of antibiotics in animal feeding

The use of antibiotics in animal feeding has been banned in many countries because of increasing concerns about the development of bacterial resistance to antibiotics and potential issues on food safety. Searching for antibiotic substitutes is essential. Applying transgenerational epigenetic technology to animal production could be an alternative. Some environmental changes can be transferred to memory-like responses in the offspring through epigenetic mechanisms without changing the DNA sequence. In this paper, we reviewed those nutrients and non-nutritional additives that have transgenerational epigenetic effects, including some amino acids, vitamins, and polysaccharides. The paternal transgenerational nutritional epigenetic regulation was particularly focused on mechanism of the substantial contribution of male stud animals to the animal industries. We illustrated the effects of paternal transgenerational epigenetics on the metabolism and immunity in farming animals and proposed strategies to modulate male breeding livestock or poultry.

Seminal Microbiota of Idiopathic Infertile Patients and Its Relationship With Sperm DNA Integrity

The development of new biomarkers for human male infertility is crucial to improve the diagnosis and the prognosis of this disease. Recently, seminal microbiota was shown to be related to sperm quality parameters, suggesting an effect in human fertility and postulating it as a biomarker candidate. However, its relationship to sperm DNA integrity has not been studied yet. The aim of the present study is to characterize the seminal microbiota of a western Mediterranean population and to evaluate its relationship to sperm chromatin integrity parameters, and oxidative stress. For that purpose, 14 samples from sperm donors and 42 samples from infertile idiopathic patients were obtained and were analyzed to assess the composition of the microbiota through full-length 16S rRNA gene sequencing (Illumina MiSeq platform). Microbial diversity and relative abundances were compared to classic sperm quality parameters (macroscopic semen parameters, motility, morphology and concentration), chromatin integrity (global DNA damage, double-stranded DNA breaks and DNA protamination status) and oxidative stress levels (oxidation-reduction potential). The seminal microbiota observed of these samples belonged to the phyla Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. The most abundant genera were Finegoldia, Peptoniphilus, Anaerococcus, Campylobacter, Streptococcus, Staphylococcus, Moraxella, Prevotella, Ezakiella, Corynebacterium and Lactobacillus. To our knowledge, this is the first detection of Ezakiella genus in seminal samples. Two clusters of microbial profiles were built based on a clustering analysis, and specific genera were found with different frequencies in relation to seminal quality defects. The abundances of several bacteria negatively correlate with the sperm global DNA fragmentation, most notably Moraxella, Brevundimonas and Flavobacterium. The latter two were also associated with higher sperm motility and Brevundimonas additionally with lower oxidative-reduction potential. Actinomycetaceae, Ralstonia and Paenibacillus correlated with reduced chromatin protamination status and increased double-stranded DNA fragmentation. These effects on DNA integrity coincide in many cases with the metabolism or enzymatic activities of these genera. Significant differences between fertile and infertile men were found in the relative presence of the Propionibacteriaceae family and the Cutibacterium, Rhodopseudomonas and Oligotropha genera, which supports its possible involvement in male fertility. Our findings sustain the hypothesis that the seminal microbiome has an effect on male fertility.

Microbiomes of the Sydney Rock Oyster are acquired through both vertical and horizontal transmission

Background

The term holobiont is widely accepted to describe animal hosts and their associated microorganisms. The genomes of all that the holobiont encompasses, are termed the hologenome and it has been proposed as a unit of selection in evolution. To demonstrate that natural selection acts on the hologenome, a significant portion of the associated microbial genomes should be transferred between generations. Using the Sydney Rock Oyster (Saccostrea glomerata) as a model, we tested if the microbes of this broadcast spawning species could be passed down to the next generation by conducting single parent crosses and tracking the microbiome from parent to offspring and throughout early larval stages using 16S rRNA gene amplicon sequencing. From each cross, we sampled adult tissues (mantle, gill, stomach, gonad, eggs or sperm), larvae (D-veliger, umbo, eyed pediveliger, and spat), and the surrounding environment (water and algae feed) for microbial community analysis.

Results

We found that each larval stage has a distinct microbiome that is partially influenced by their parental microbiome, particularly the maternal egg microbiome. We also demonstrate the presence of core microbes that are consistent across all families, persist throughout early life stages (from eggs to spat), and are not detected in the microbiomes of the surrounding environment. In addition to the core microbiomes that span all life cycle stages, there is also evidence of environmentally acquired microbial communities, with earlier larval stages (D-veliger and umbo), more influenced by seawater microbiomes, and later larval stages (eyed pediveliger and spat) dominated by microbial members that are specific to oysters and not detected in the surrounding environment.

Conclusion

Our study characterized the succession of oyster larvae microbiomes from gametes to spat and tracked selected members that persisted across multiple life stages. Overall our findings suggest that both horizontal and vertical transmission routes are possible for the complex microbial communities associated with a broadcast spawning marine invertebrate. We demonstrate that not all members of oyster-associated microbiomes are governed by the same ecological dynamics, which is critical for determining what constitutes a hologenome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-022-00186-9.

Microbiota in Goat Buck Ejaculates Differs Between Breeding and Non-breeding Seasons

Changes in semen microbiota are associated with alterations to sperm quality and fertility. However, the microbiota from most livestock species has not yet been studied. Goats are seasonal breeders, but semen microbiota has never been described in this species, and it is unknown how seasonality affects it. Our study objective is 2-fold: to describe the microbiota in goat buck ejaculates and to determine if it differs between breeding and non-breeding seasons. Semen from six males of the Murciano-Granadina breed was collected during both seasons. Two replicates were performed per male and season on different days. The microbiota was characterized by genomic sequencing technology. Sperm quality was also evaluated. Repetition was not significant for the studied variables. Sperm velocities were higher for the breeding than for the non-breeding season. The ejaculates from both seasons also differed in the proportion of apoptotic spermatozoa. The five dominant phyla were Firmicutes, Proteobacteria, Fusobacteria, Actinobacteria, and Bacteroidetes during the breeding season and Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria during the non-breeding season. The dominant genus during both seasons was Ureaplasma. Differences in microbial community structure (the beta diversity) were found. A decrease in the relative abundance of the genus Faecalibacterium and an increase in the genera Sphingomonas and Halomonas were observed in the ejaculates collected during the breeding season. Sphingomonas and Faecalibacterium abundance favorably and unfavorably correlated with sperm quality, respectively. In conclusion, the semen microbiota from goat bucks varies between breeding and non-breeding seasons, and the microbiota remains stable for 7 days within a season. In addition, the genera Sphingomonas and Faecalibacterium could be possible biomarkers of semen quality in goat bucks. These results contribute to an in-depth understanding of the effects of reproductive seasonality on goat buck ejaculates.

Ligilactobacillus salivarius PS11610 exerts an effect on the microbial and immunological profile of couples suffering unknown infertility

PROBLEM

Unknown or idiopathic infertility has been associated with urogenital tract dysbiosis, reducing pregnancy and delivery ratios during assisted reproductive treatments (ART). The Ligilactobacillus salivarius PS11610 strain has shown extraordinary antimicrobial activity in vitro against urogenital pathogens as well as other probiotic characteristics. Therefore, an intervention study was performed to evaluate the effect of L. salivarius PS11610 on the microbial composition of urogenital tract in infertile couples with bacterial dysbiosis.

METHOD OF STUDY

Seventeen couples undergoing ART diagnosed with unknown infertility were selected. After confirming urogenital dysbiosis, they started a 6-month treatment with L. salivarius PS11610 (1 dose/12 h for female and 1 dose/24 h for male). Vaginal, seminal, glans, uterine and plasma samples were collected for determination of the microbiome and immune profile at the beginning and the end of the treatment.

RESULTS

Supplementation with L. salivarius PS11610 significantly modified the urogenital microbiome composition in male and female samples, solving dysbiosis of 67% of the couples. Pathogens disappeared from the vaginal samples whereas Lactobacilli percentage increased after 3 and 6 months of treatment. Moreover, L. salivarius PS11610 changed the uterine microbiome that could be associated with a change of the uterine immune profile. Additionally, the probiotic intake could be associated with the observed change in the systemic immunological profile of couples. Finally, the pregnant and delivery ratio were improved.

CONCLUSIONS

Probiotic supplementation with L. salivarius PS11610 improved the male and female urogenital tract microbiome, modulating the immune system and increasing pregnancy success in couples undergoing ART.

Paternal periconception metabolic health and offspring programming

The association between maternal metabolic status at the time of conception and subsequent embryogenesis and offspring development has been studied in detail. However, less attention has been given to the significance of paternal nutrition and metabolism in directing offspring health. Despite this disparity, emerging evidence has begun to highlight an important connection between paternal metabolic well-being, semen quality, embryonic development and ultimately adult offspring health. This has established a new component within the Developmental Origins of Health and Disease hypothesis. Building on the decades of understanding and insight derived from the numerous models of maternal programming, attention is now becoming focused on defining the mechanisms underlying the links between paternal well-being, post-fertilisation development and offspring health. Understanding how the health and fitness of the father impact on semen quality is of fundamental importance for providing better information to intending fathers. Furthermore, assisted reproductive practices such as in vitro fertilisation rely on our ability to select the best quality sperm from a diverse and heterogeneous population. With considerable advances in sequencing capabilities, our understanding of the molecular and epigenetic composition of the sperm and seminal plasma, and their association with male metabolic health, has developed dramatically over recent years. This review will summarise our current understanding of how a father's metabolic status at the time of conception can affect sperm quality, post-fertilisation embryonic and fetal development and offspring health.

Perspective on the relationship between reproductive tract microbiota eubiosis and dysbiosis and reproductive function

The role played by microbiota is attracting growing attention within the scientific and medical community, in both human and animal fields, in the last years. Most of the studies have been focused on the intestinal microbiome, whilst little attention has been paid to other systems, like the reproductive tract of both females and males. However, there is a growing body of information showing the interplay between reproductive tract dysbiosis, due to the action of pathogens and/or unhealthy lifestyle, and reproductive disease and disorders in many mammalian species. The present review aims to summarise current knowledge on the biodiversity of the microbiota of the reproductive tract, and the possible relationships between eubiosis or dysbiosis and reproductive health and function in both females and males.

The Microbiome, an Important Factor That Is Easily Overlooked in Male Infertility

Humankind has been interested in reproduction for millennia. Infertility, in which male factors contribute to approximately 50%, is estimated to concern over 72 million people worldwide. Despite advances in the diagnosis, medical treatment, and psychosocial management of male infertility over the past few decades, approximately 30% of male infertility is still thought to be idiopathic. Despite emerging advances in the microbiome associated with male infertility have indicated that the microbiome may be a key factor to the management of male infertility, roles, and mechanisms of the microbiome remain ambiguous. Here, we mainly discussed the association between microbial infection in the genital tract and male infertility, effect of antimicrobial therapy on male reproduction, association between microbial dysbiosis and male infertility, and effect of probiotic intervention on male reproduction. This review made progress toward establishing a relationship between the microbiome and male infertility, and explored the role of the microbiome in male infertility. We call for more high-quality studies to focus on the relationship between microbes and male infertility, and strongly suggest increasing awareness among sterile males with microbial infection and/or microbial dysbiosis when they seek fertility help.

Spermatic Microbiome Characteristics in Infertile Patients: Impact on Sperm Count, Mobility, and Morphology

Through sperm alteration, semen microbiota tend to be recognized as a cause of infertility, but due to the limited number of studies focusing on this ecological niche, this hypothesis remains controversial. This study aimed to characterize and compare the bacterial communities of sperm samples from patients undergoing couple infertility treatment at the time of diagnosis. The study was prospective (September 2019 to March 2020), monocentric, and focused on alterations of spermatic parameters: count, motility, and morphology. After the amplification of the 16S rDNA (V1 to V3), libraries (n = 91, including 53 patients with abnormalities) were sequenced using the MiSeq platform (Illumina). After quality control processing using a homemade pipeline (QIIME2 modules), the main genera were: Prevotella, Finegoldia, Pseudomonas, Peptinophilus, Streptococcus, Anaerococcus and Corynebacterium. Restricted diversity was observed in samples from patients with abnormal sperm morphology (α-diversity, p < 0.05), whereas diversity increased in patients with an abnormal sperm count (β-diversity, p < 0.05). The enrichment of the genus Prevotella and Haemophilus was observed in negative sperm culture samples and samples with abnormal counts, respectively (p < 0.05). Microbiota differed in their composition according to sperm parameters. Finally, this work highlights the need for the optimization of the management of couples undergoing infertility treatment, possibly by modulating the genital microbiome.

Cultivable vaginal Lactobacillus is not associated with fecundability in Kenyan women attempting to conceive

OBJECTIVE

To examine the association between cultivable vaginal Lactobacillus and fecundability in Kenyan women attempting nonmedically assisted conception.

DESIGN

Prospective preconception cohort.

SETTING

Nairobi and Mombasa, Kenya.

PATIENT(S)

Women trying to conceive who reported ≤3 months of pre-enrollment conception attempt time.

INTERVENTION(S)

Cultivable Lactobacillus (primary), Lactobacillus morphotypes on Gram stain (secondary).

MAIN OUTCOME MEASURE(S)

Participants reported the first day of their last menstrual period and recent sexual behavior, underwent pregnancy testing, and provided vaginal specimen samples for Lactobacillus culture and Gram stain at ≤6 monthly preconception visits. The outcome was fecundability-the per-menstrual cycle probability of pregnancy. Associations between cultivable Lactobacillus and Lactobacillus morphotypes on Gram stain at the visit before each pregnancy test and fecundability were estimated using proportional probabilities models to generate fecundability ratios (FRs).

RESULT(S)

A total of 458 women contributed 1,376 menstrual cycles. At enrollment, 65.3% (n = 299) of participants had cultivable Lactobacillus, 47.4% (n = 217) had cultivable hydrogen peroxide producing Lactobacillus, and 64.6% (n = 296) had Lactobacillus detected on Gram stain. In unadjusted analysis, there was no association between cultivable Lactobacillus at the prior visit and fecundability (FR, 0.92; 95% CI, 0.73-1.16); results were similar after adjustment for age, frequency of condomless sex, and study site (adjusted FR, 0.92; 95% CI, 0.72-1.18). Lactobacillus on Gram stain at the visit prior was associated with modestly higher fecundability (adjusted FR, 1.18; 95% CI, 0.92-1.51).

CONCLUSION(S)

Cultivable Lactobacillus was not associated with fecundability, although Lactobacillus morphotypes detected on Gram stain were somewhat associated with increased fecundability. The relationship between vaginal Lactobacillus and fecundity may be species-specific.

Characterization of the Gastrointestinal and Reproductive Tract Microbiota in Fertile and Infertile Pakistani Couples

Simple Summary

We describe microbial taxa associated with the gastrointestinal and reproductive tracts of married Pakistani couples. We highlight differences in microbial composition and diversity that are associated with fertile and infertile couples and provide a baseline for future in-depth studies to target the association of the human microbiome with infertility.

Abstract

The human microbiota is recognized as a vital “virtual” organ of the human body that influences human health, metabolism, and physiology. While the microbiomes of the gut, oral cavity, and skin have been extensively studied in the literature, relatively little work has been done on characterizing the microbiota of the human reproductive tract organs, and specifically on investigating its association to fertility. Here, we implemented a 16S ribosomal RNA (rRNA) amplicon sequencing approach to sequence and characterize the gut and genital tract microbiomes from several married Pakistani couples. The recruited individuals included 31 fertile and 35 infertile individuals, with ages ranging from 19–45 years. We identified several fluctuations in the diversity and composition of the gut and genital microbiota among fertile and infertile samples. For example, measures of α-diversity varied significantly between the genital samples donated by fertile and infertile men and there was overall greater between-sample variability in genital samples regardless of gender. In terms of taxonomic composition, Actinobacteria, Bacteroidetes, and Firmicutes fluctuated significantly between the gut microbiomes of fertile and infertile samples. Finally, biomarker analyses identified features (genera and molecular functions and pathways) that differed significantly between the fertile and infertile samples and in the past have been associated with bacterial vaginosis. However, we emphasize that 16S amplicon data alone has no bearing on individual health and is merely representative of microbial taxonomic differences that could also arise due to multiple other factors. Our findings, however, represent the first effort to characterize the microbiome associated with fertile and infertile couples in Pakistan and will hopefully pave the way for more comprehensive and broad-scale investigations in the future.

The Impact of Bacteriocenoses on Sperm Vitality, Immunological and Oxidative Characteristics of Ram Ejaculates: Does the Breed Play a Role?

Bacterial contamination of semen is an often overlooked, yet important, factor contributing to decreased sperm vitality. Understanding the impact of bacterial presence on sperm structural integrity and functional activity may assist the development of effective strategies to prevent, or manage, bacteriospermia in the breeding practice. The aim of this study was to describe the bacterial profiles of ram semen (n = 35), and we also focused on the associations between bacteriospermia, sperm structure, and function, as well as oxidative and inflammatory characteristics of semen. For a better insight, the samples were divided into three groups, according to the breeds used in the study: native Wallachian (NW), improved Wallachian (IW), and Slovak dairy (SD) breeds. The results showed a significantly lower motility and membrane integrity in the NW group in comparison to the IW and SD groups, which was accompanied by a significantly higher concentration of leukocytes, increased reactive oxygen species (ROS) generation, and subsequent oxidative insults to the sperm lipids and proteins. Accordingly, the NW group presented with the highest bacterial load, in which Staphylococcus and Escherichia were the predominant representatives. The Pearson correlation analysis uncovered positive relationships amongst the bacterial load and leukocytospermia (r = 0.613), the extent of lipid peroxidation (r = 0.598), protein oxidation (r = 0.514), and DNA fragmentation (r = 0.638). Furthermore, positive correlations were found between the bacterial load and pro-inflammatory molecules, such as the C-reactive protein (r = 0.592), interleukin 1 (r = 0.709), and interleukin 6 (r = 0.474), indicating a possible involvement of the immune response in the process of bacteriospermia. Overall, our data indicate that ram semen quality may be equally affected by the bacterial load and diversity. Furthermore, we can assume that the presence of bacteria in ejaculates triggers inflammatory processes, causes ROS overproduction, and, thereby, contributes to alterations in the sperm structure, while at the same time compromising the fertilization ability of male gametes.

Analysis of Microbial Communities: An Emerging Tool in Forensic Sciences

The objective of forensic sciences is to find clues in a crime scene in order to reconstruct the scenario. Classical samples include DNA or fingerprints, but both have inherent limitations and can be uninformative. Another type of sample has emerged recently in the form of the microbiome. Supported by the Human Microbiome Project, the characteristics of the microbial communities provide real potential in forensics. They are highly specific and can be used to differentiate and classify the originating body site of a human biological trace. Skin microbiota is also highly specific and different between individuals, leading to its possibility as an identification tool. By extension, the possibilities of the microbial communities to be deposited on everyday objects has also been explored. Other uses include the determination of the post-mortem interval or the analysis of soil communities. One challenge is that the microbiome changes over time and can be influenced by many environmental and lifestyle factors. This review offers an overview of the main methods and applications to demonstrate the benefit of the microbiome to provide forensically relevant information.

Evaluation of SARS-CoV-2 in semen, seminal plasma, and spermatozoa pellet of COVID-19 patients in the acute stage of infection

To date, there is limited information about the presence of SARS-CoV-2 in semen especially in the acute phase of the infection. While available data from cohort studies including a total of 342 patients in the acute or recovery phase of the infection are reassuring, one study mentioned detecting virus in the semen of 6/38 COVID-19 patients. Here we assessed SARS-CoV-2 presence in the semen of COVID-19 positive patients in the acute stage of infection, within 24 hours of the positive nasopharyngeal swabs. Semen, seminal plasma and spermatozoa pellet were screened for SARS-CoV-2 and manual or airborne contamination during semen sampling. Among the 32 COVID-19 volunteers, the median interval from the onset of symptoms to semen collection was 4 days [IQR: 0-8]. Only one presented positive SARS-CoV-2 PCR in semen and seminal plasma fractions, although the spermatozoa pellet was negative. Viral cultures were all negative. We observed slightly higher concentrations of bacterial DNA in the SARS-CoV-2 positive specimen than in all negative samples. The bacteria identified neither confirm nor rule out contamination by oropharyngeal secretions during collection. SARS-CoV-2 was rarely present in semen during the acute phase of the disease. This very rare situation could be connected to oral or manual contamination during semen collection. The possible presence of SARS-CoV-2 in semen calls for nasopharyngeal viral testing and strict hygiene protocols during semen collection before assisted reproductive attempts.

Seminal and testicular microbiome and male fertility: A systematic review

Supplemental Digital Content is available in the text

Microbiome is of upmost importance for the well-being of the human body. Based on culture and PCR methods, seminal flora has been pointed as a potential cause for some of the unexplained male infertility.

This is a systematic review about the effect of seminal microbiota studied by Next Generation Sequencing techniques on sperm quality and male fertility, performed according to PRISMA statement.

Nine articles were included. Results of different studies are diverse. It seems that microbiota may a play a role in seminal quality and further male fertility, but the way this effect is modulated is still to be unknown. Lactobacillus spp seemed to play a beneficial role in semen quality, but the role of the remaining bacteria is unclear.

Due to the lack of research and the incongruence of the results so far, the effect of microbiota on seminal quality is still unclear.

Semen microbiota in normal and leukocytospermic males

Large numbers of microbes can be present in seminal fluid, and there are differences in the semen microbiota between normal and abnormal semen samples. To evaluate the semen microbiota in patients with leukocytospermia, 87 seminal fluid samples, including 33 samples with a normal seminal leukocyte count and 54 samples with leukocytospermia, were obtained for a cross-sectional analysis. Twenty samples with a normal seminal leukocyte count had normal sperm parameters (Control group), and 13 samples with a normal seminal leukocyte count were from asthenozoospermia patients (Ast group). However, 32 samples with leukocytospermia were from asthenozoospermia patients (LA group), and only 22 samples with leukocytospermia had normal sperm parameters (Leu group). The 16S ribosomal RNA (rRNA) gene sequencing method was used to sequence the microbiota in the seminal fluid, and multiple bioinformatics methods were utilized to analyze the data. Finally, the results showed that the worse sperm parameters were observed in the leukocytospermia-related groups. Semen microbiota analysis found that there was increased alpha diversity in the leukocytospermia-related groups. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the primary phyla in the seminal fluid. Two microbiota profiles, namely, Lactobacillus-enriched and Streptococcus-enriched groups, were identified in this study. The majority of the samples in the groups with a normal seminal leukocyte count could be categorized as Lactobacillus-enriched, whereas the majority of the leukocytospermia samples could be categorized as Streptococcus-enriched. Our study indicated that males with leukocytospermia have worse sperm parameters and a different semen microbiota composition compared to males with a normal seminal leukocyte count.

Identification of Bull Semen Microbiome by 16S Sequencing and Possible Relationships with Fertility

Reports on the use of 16S sequencing for the identification of bacteria in healthy animals are lacking. Bacterial contamination of bull semen can have a negative effect on the sperm quality. The aims of this study were threefold: to identify bacteria in the semen of healthy bulls using 16S sequencing; to investigate the differences in the bacterial community between individual bulls; and to establish if there was a relationship between the bacteria isolated and bull fertility. Semen from 18 bulls of known fertility was used for the DNA extraction and 16S sequencing; 107 bacterial genera were identified. The differences in the amplicon sequence variants (ASVs) and the numbers of genera between bulls were noted. Negative correlations (p < 0.05) between several bacterial genera with Curvibacter, Rikenellaceae RC9-gut-group and Dyella spp. were seen. Other negatively correlated bacteria were Cutibacterium, Ruminococcaceae UCG-005, Ruminococcaceae UCG-010 and Staphylococcus, all within the top 20 genera. Two genera, W5053 and Lawsonella, were enriched in bulls of low fertility; this is the first time that these bacteria have been reported in bull semen samples. The majority of the bacteria were environmental organisms or were species originating from the mucous membranes of animals and humans. The results of this study indicate that differences in the seminal microbiota of healthy bulls occur and might be correlated with fertility.

Core Microbiome of Slovak Holstein Friesian Breeding Bulls' Semen

Simple Summary

The aim of this study was to characterize the bacterial profile of semen collected from Holstein Friesian breeding bulls via a high-throughput sequencing approach for a 16S rRNA gene variability analysis. A total of 55 fresh semen samples of sexually mature breeding bulls were used in the study. They were gathered from Holstein Friesian breeding bulls at Slovak Biological Services in Nitra, Slovak Republic. To amplify the V4 region of the 16S rRNA bacterial gene, universal primers 515F and 806R enhanced by a 6 bp barcode identification sequence were used. The 16S rRNA high-throughput sequencing strategy was used. Two microbial clusters were identified among the analyzed samples—the first cluster was based on Actinobacteria and Firmicutes, while the second cluster contained a high prevalence of Fusobacteria.

Abstract

Bacterial contamination of semen is an important factor connected to the health status of bulls that may significantly affect semen quality for artificial insemination. Moreover, some important bovine diseases may be transmitted through semen. Up to now, only a very limited number of complex studies describing the semen microbiome of bulls have been published, as many bacteria are hard to cultivate using traditional techniques. The 16S rRNA high-throughput sequencing strategy allows for the reliable identification of bacterial profiles of bovine semen together with the detection of noncultivable bacterial species. Fresh samples from Holstein Friesian breeding bulls (n = 55) were examined for the natural variability in the present bacteria. Semen doses were selected randomly from Slovak Biological Services in Nitra, Slovak Republic. The most predominant phyla within the whole dataset were Firmicutes (31%), Proteobacteria (22%), Fusobacteria (18%), Actinobacteria (13%) and Bacteroidetes (12%). Samples of semen were divided into two separate clusters according to their microbiome compositions using a cording partition around a medoids analysis. Microbiomes of the first cluster (CL1) of samples (n = 20) were based on Actinobacteria (CL1 average = 25%; CL = 28%) and Firmicutes (CL1 = 38%; CL2 = 27%), while the second cluster (CL2; n = 35) contained samples characterized by a high prevalence of Fusobacteria (CL1 = 4%; CL2 = 26%). Some important indicator microbial groups were differentially distributed between the clusters.

The Efficiency of Selected Extenders against Bacterial Contamination of Boar Semen in a Swine Breeding Facility in Western Slovakia

Simple Summary

This study evaluated the efficiency of selected semen extenders to prevent bacterial overgrowth in boar ejaculates stored for 72 h. Among the identified bacterial isolates, Escherichia coli and Pseudomonas aeruginosa were the most prevailing species. While all extenders supplemented with antibiotics ensured a satisfactory sperm vitality during the storage period, neither of them was able to achieve a complete elimination of bacteria from extended semen. Furthermore, a number of bacterial isolates exhibited resistance to several antibiotics chosen for the microbial susceptibility test (e.g., tigecyklin and ciprofloxacin).

Abstract

Bacteriospermia has become a serious factor affecting sperm quality in swine breeding, this is why antibiotics (ATBs) are a critical component of semen extenders. Due to ever-increasing antimicrobial resistance, the aim of this study was to assess the efficiency of selected commercially available semen extenders to prevent a possible bacterial contamination of boar ejaculates. Three Androstar Plus extenders containing different combinations of antibiotics were used to process ejaculates from 30 healthy Duroc breeding boars. Androstar Plus without antibiotics was used as a control. The extended samples were stored at 17 °C for 72 h. Sperm motility, viability, mitochondrial activity, DNA integrity and oxidative profile of each extended sample were assessed following 24 h, 48 h and 72 h. Furthermore, selective media were used to quantify the bacterial load and specific bacterial species were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The results indicate that semen extenders enriched with ATBs ensured a significantly higher preservation of the sperm quality in comparison to the ATB-free control. The total bacterial count was significantly decreased in the extenders supplemented with ATBs (p < 0.001), however gentamycin alone was not effective enough against Gram-positive bacteria, while a few colonies of Enterococcus hirae, Bacillus subtilis and Corynebacterium spp. were present in the samples extended in the presence of a triple combination of ATBs. In conclusion, we may suggest that semen extenders enriched in antibiotics were not able to fully eliminate the bacteria present in the studied samples. Furthermore, selection of suitable antibiotics for semen extension should be accompanied by adequate hygiene standards during the collection and handling of boar ejaculates.

The search for aliens within us: a review of evidence and theory regarding the foetal microbiome

The microbiome is believed to be established during the birthing process through exposure to the maternal microbiome and immediate external environment. The absence of a microbiome prior to birth is based on the sterile womb hypothesis, which was formulated at the beginning of the 20th century and is supported primarily by the culture-based approach in microbiological studies.Findings of bacterial presence in products of fertilization such as the placenta, amniotic fluid, foetal membranes, and umbilical cord blood in studies using next-generation DNA sequencing technologies began to challenge the sterile nature of the intrauterine environment during gestation. These studies have been mainly criticized by their approach to contamination and inconclusive evidence of viability. The implications of bacterial presence in utero are far reaching in medicine and basic sciences. If commensal bacteria exist in the foetus, antibiotic therapies in pregnancy particularly for asymptomatic cases will need to be re-evaluated. Experimental studies utilizing gnotobiology may also be impacted by a realignment of theory.This review of existing literature aims to provide insight into the existence of bacteria in utero, specifically the foetal microbiome through analysis of experimental evidence and theoretical concepts, and to suggest approaches that may further provide clarity into this inquiry.

Microbiota of semen samples with normozoospermia: analysis of real-time PCR data

The analysis of semen microbiota is difficult due to the lack of established criteria for interpretation of microbiological tests. The aim of the study was to determine the stable clusters of semen microbiota analyzed by real-time PCR in samples with normozoospermia. Semen samples of 227 men with normal spermiograms were included in the study. The quantity of total bacterial DNA and at least one group of microorganisms was more than 103 GE/ml in 107 (41.7%) samples. Four stable microbiota clusters with the prevalence of a specific microorganism group were distinguished in these samples: obligate anaerobes (OA) cluster (proportion in the centroid — 81.1%); Lactobacillus spp. cluster (proportion in the centroid — 64.3%); gram-positive facultative anaerobes (GPFA) cluster (proportion in the centroid — 92.5%); Enterobacteriaceae/Enterococcoccus (EE) cluster (proportion in the centroid — 80.8%). The clusters were ranked by frequency of occurrence: OA cluster was the most prevalent (43 (40.2%) of 107), second-most frequent were GPFA-cluster (27 (25.2%)) and Lactobacillus-cluster (22 (20.6%)). EE-dominated cluster was found in 15 (14.0%) cases.

Using the PCR and Blood Agar in Diagnosis of Semen Bacterial Contamination of Fertile and Infertile Men

BACKGROUND

One of the causes of male infertility is Genital tract infections (GTI). Considering the importance of GTI, widespread recognition of them seems necessary. we aimed to characterize and compare semen microbial populations in fertile and infertile men who referred to an infertility clinic in Yazd, Iran.

METHODS

Semen samples were collected from two groups of fertile (268) and infertile (210) men. Sperm analysis (concentration, morphology, viability and motility parameters) were performed according to the World Health Organization (WHO) 2010 guidelines laboratory manual. Bacterial isolation was performed in Sheep Blood Agar and Eosin Methylene Blue (EMB) agar plates. For PCR, samples were analyzed with genus specific primers.

RESULTS

All semen characteristics were poor in the infertile group compared to those in the fertile men (p-value< 0.05). Enterococcus spp. (18.7%, 17.1%; p= 0.814), E. coli (7.9%, 11.4%; p= 0.486), Staphylococcus aureus (6.4%, 2.9%; p= 0.398) and Proteus mirabilis (0%, 2.9%; p= 0.002) were the most common agents, respectively. Also, the results obtained from PCR were confirmed using culture-base method.

CONCLUSION

Proteus mirabilis contamination was identified in the infertile group. While no significant association was observed between male infertility and semen microbial populations, p. mirabilis may be the leading cause of reproduction impairment in men.

The relationship between sexually transmitted bacteria, microbiota and seminal quality in asymptomatic men

Objective

To detect DNA of different microorganisms, in semen samples from apparently healthy men and correlate their presence with seminal quality.

Methods

Semen samples from 81 healthy volunteers were collected, and semen parameters were analyzed. DNA extraction was performed using the phenol-chloroform technique, and the microorganisms were detected by the amplification of specific primers using polymerase chain reaction.

Results

DNA from at least one of the microorganisms was detected in 78 samples. The most frequent microorganism found in semen were: Lactobacillus spp. (70%), Neisseria gonorrhoeae (N. gonorrhoeae) (36%), Streptococcus epidermidis (64%), Klebsiella pneumoniae (56%), Staphylococcus aureus (32%), Chlamydia trachomatis (C. trachomatis) (28%), Pseudomonas aeruginosa (27%). The seminal parameters of all semen samples were over the lower reference values for normal semen analysis. To compare with negative samples, seminal volume was higher for the Escherichia coli positive samples and lower for Pseudomonas aeruginosa positive samples. Semen samples positive for Staphylococcus aureus had worse sperm morphology. The frequency of progressive motility was higher in positive samples for N. gonorrhoeae and C. trachomatis. Positive semen samples for C. trachomatis had a higher concentration per milliliter.

Conclusion

It is common to find microorganisms in semen of asymptomatic men, including those responsible for sexually transmitted infections. Antimicrobial treatment is recommended only in those individuals with a sexually transmitted infection (C. trachomatis and N. gonorrhoeae) and always promote condom use.

Proinflammatory and Oxidative Stress States Induced by Human Papillomavirus and Chlamydia trachomatis Coinfection Affect Sperm Quality in Asymptomatic Infertile Men

Background and Objectives: To investigate the effect of infection with human papillomavirus (HPV) or Chlamydia trachomatis (CT) and HPV + CT coinfection on sperm quality, inflammation, and the state of oxidative stress (OS) in asymptomatic infertile men. Materials and Methods: Semen samples from 84 asymptomatic military infertile men were studied. The polymerase chain reaction (PCR) was used for the molecular detection of HPV and CT. Semen parameters were analyzed according to the World Health Organization guidelines. Inflammation was evaluated by an IL-1β, IL-6, and IFN-γ enzyme-linked immunosorbent assay (ELISA) and OS by the quantification of lipid peroxidation (LPO), 8-hydroxydeoxyguanosine (8-OHdG), and total antioxidant capacity (TAC). Results: A total of 81 of the 84 (96.4%) samples were positives for the pathogens, with 55/81 (68%) being positive for HPV, 11/81 (13.5%) for CT, and 15/81 (18.5%) for HPV + CT coinfection. Seminal parameters were affected in the infected groups, including pH increases above the normal range in all groups. An abnormal sperm morphology was observed in the HPV and HPV + CT groups. Higher cytokine levels were detected in the HPV group and the highest IL-1β level was found in the HPV + CT group. No cytokines were detected in the CT group. High LPO and 8-OHdG levels were found in all groups with a lower TAC. Comparisons between groups showed the highest OS state was observed in the HPV group. Conclusions: High HPV infection or coinfection (HVP + CT) in these infertile men suggest compromising male fertility by inducing a proinflammatory state and OS. Infection with CT suggests an alteration of the state of OS by promoting an alkaline pH.

Effect of bacterial infection on sperm quality and DNA fragmentation in subfertile men with Leukocytospermia

Background

Although bacterial infections have been recognized as a possible cause of male infertility, the effect of bacterial infections on sperm quality and sperm DNA fragmentation remains controversial. The current study aimed to investigate the prevalence rate of bacterial infection in subfertile men and its effect on semen quality. Seminal fluid was collected from 172 male members of infertile couples attending the andrology infertility center and a group of 35 fertile subjects as a control. Sperm parameters and DNA fragmentation were evaluated based on the type of bacteria in all ejaculates.

Results

From the 172 patients investigated for infertility, 60 (34.88%) patients had a positive culture for pathogenic bacteria of different species. Leukocytospermia was significantly higher in infected samples in comparison with non-infected samples (p < 0.05). Sperm concentration and motility and morphology were significantly lower in infected than non-infected samples. Moreover, sperm DNA fragmentation was significantly higher in infected than non-infected samples. Besides, our results showed that sperm DNA fragmentation was correlated significantly with leukocytospermia (R: 0.22, p < 0.01).

Conclusion

The present study suggested that bacterial infection significantly correlated with leukocytospermia could impair male fertility potential through decreasing sperm motility, morphology, and DNA integrity.

Assessing the testicular sperm microbiome: a low-biomass site with abundant contamination

RESEARCH QUESTION

The semen harbours a diverse range of microorganisms. The origin of the seminal microbes, however, has not yet been established. Do testicular spermatozoa harbour microbes and could they potentially contribute to the seminal microbiome composition?

DESIGN

The study included 24 samples, comprising a total of 307 testicular maturing spermatozoa. A high-throughput sequencing method targeting V3 and V4 regions of 16S rRNA gene was applied. A series of negative controls together with stringent in-silico decontamination methods were analysed.

RESULTS

Between 50 and 70% of all the detected bacterial reads accounted for contamination in the testicular sperm samples. After stringent decontamination, Blautia (P = 0.04), Cellulosibacter (P = 0.02), Clostridium XIVa (P = 0.01), Clostridium XIVb (P = 0.04), Clostridium XVIII (P = 0.02), Collinsella (P = 0.005), Prevotella (P = 0.04), Prolixibacter (P = 0.02), Robinsoniella (P = 0.04), and Wandonia (P = 0.04) genera demonstrated statistically significant abundance among immature spermatozoa.

CONCLUSIONS

Our results indicate that the human testicle harbours potential bacterial signature, though in a low-biomass, and could contribute to the seminal microbiome composition. Further, applying stringent decontamination methods is crucial for analysing microbiome in low-biomass site.

Chlamydia trachomatis infection in the genital tract is associated with inflammation and hypospermia in the infertile male of China

Chlamydia trachomatis (CT) infection is the most prevalent sexually transmitted bacterial disease worldwide. However, unlike that in female infertility, the role of CT infection in male infertility remains controversial. The objective of this retrospective study was to explore the impacts of CT infection in the genital tract on sperm quality, sperm acrosin activity, antisperm antibody levels, and inflammation in a large cohort of infertile males in China. A total of 7154 semen samples were collected from infertile male subjects, 416 of whom were CT positive (CT+ group) and 6738 of whom were CT negative (CT− group), in our hospital between January 2016 and December 2018. Routine semen parameters (semen volume, pH, sperm concentration, viability, motility, morphology, etc.), granulocyte elastase levels, antisperm antibody levels, and sperm acrosin activity were compared between the CT+ and CT− groups. Our results showed that CT infection was significantly correlated with an abnormally low semen volume, as well as an increased white blood cell count and granulocyte elastase level (all P < 0.05) in the semen of infertile males; other routine semen parameters were not negatively impacted. The antisperm antibody level and sperm acrosin activity were not affected by CT infection. These findings suggested that CT infection might contribute to inflammation and hypospermia but does not impair sperm viability, motility morphology, and acrosin activity or generate antisperm antibodies in the infertile males of China.

Connecting the Dots: Translating the Vaginal Microbiome Into a Drug

A Lactobacillus-dominated vaginal microbiota (VMB) has been associated with health and considered an important host defense mechanism against urogenital infections. Conversely, depletion of lactobacilli and increased microbial diversity, amplifies the risk of adverse gynecologic and obstetric outcomes. A common clinical condition that exemplifies dysbiosis is bacterial vaginosis (BV). BV is currently treated with antibiotics, but frequently recurs, due in part to persistent dysbiosis and failure of lactobacilli to repopulate the vagina. New treatment options are needed to address BV. The VMB is relatively simple and optimally dominated by one or several species of Lactobacillus. Lactobacillus crispatus is strongly associated with vaginal health and depleted in dysbiosis. Replenishing the dysbiotic VMB with protective L. crispatus CTV-05 is a promising approach to prevent recurrent infections and improve women's health. Here we discuss confirmation of this approach with the microbiome-based biologic drug, LACTIN-V (L. crispatus CTV-05), focusing on prevention of BV recurrence.

HPV infection and bacterial microbiota in the semen from healthy men

BACKGROUND

Aberrant microbiota composition has been linked to disease development at numerous anatomical sites. Microbiota changes in reaction to viral infections, such as human papillomavirus (HPV), have been investigated almost exclusively in the female reproductive tract. However, HPV infection may also affect male health by reducing semen quality and fertility. The aim of this study was to investigate whether present HPV DNA is associated with detectable changes in semen bacterial microbiota composition and diversity.

METHODS

This study relied on stored semen samples from 31 fertile healthy men who participated in the Finnish family HPV Study during the years 1998-2001. DNA was extracted from semen with PCR template preparation kit. HPV was genotyped using Luminex-based Multimetrix® assay. Microbiota was analyzed from the V3-V4 region of 16S rDNA gene following sequencing on an Illumina MiSeq platform. All statistical analyses were performed with Calypso software version 8.84.

RESULTS

HPV DNA was detected in 19.4% (6/31) of the semen samples. HPV status in the semen did not impact the α-diversity estimations, as measured by Chao1 and Shannon indices, nor ß-diversity. Nevertheless, HPV-positive semen samples exhibited differences in the taxonomic composition of the bacterial microbiota including higher abundances of Moraxellaceae (p = 0.028), Streptococcus (p = 0.0058) and Peptostreptococcus (p = 0.012) compared to HPV-negative semen samples.

CONCLUSION

HPV infection is associated with altered bacterial microbiota composition in semen, and this might have in impact to male health in general. As of present, it is unclear whether these changes result from HPV infection or whether altered bacterial microbiota increases susceptibility to HPV infection. More research is needed on viral-bacterial interactions in the male reproductive system.

Seminal pro-inflammatory cytokines and pH are affected by Chlamydia infection in asymptomatic patients with teratozoospermia

Introduction

Infection and inflammation of the reproductive tract by Chlamydia trachomatis (CT) are recognized as significant risk factors for male infertility. This study aimed to evaluate CT infection and its effects on seminal parameters and cytokines in asymptomatic patients with teratozoospermia.

Material and methods

Semen samples from one hundred four male patients were collected, and CT detection was performed by polymerase chain reaction (PCR). The quality (volume, sperm concentration, pH, motility, morphology, and leucocytes) of the semen was measured by standard procedures recommended by the World Health Organization (WHO). Pro-inflammatory cytokines [interleukin (IL)-1 β, IL-6, IL-8, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ)], as well as anti-inflammatory cytokines (IL-4, IL-10), were determined by using enzyme-linked immunosorbent assay (ELISA). The frequency of CT infection was expressed as a percentage. Descriptive statistics were used for comparison of cytokines from infertile men, and then the Mann-Whitney U test was applied for the contrast of seminal parameters and cytokines from CT-infected versus non-CT infected men.

Results

A ratio of 33/104 (31.7%) patients were positive for CT infection. The ejaculate of positive CT infection was found to have increased pH (pH = 7.65 in non-CT infected vs. 7.94 CT-infected men; p = 0.026). High levels of pro-inflammatory cytokines were found in the population studied; however, infected males were noted to have high levels of IL-1 β [184.66 (0-3985.33 pg/ml), p = 0.001] and IL-6 [87.8 (0-1042.8 pg/ml), p = 0.001].

Conclusions

CT infection increased seminal pH, as well as IL-1 β and IL-6 cytokines, suggesting a potential role of infection and inflammation in asymptomatic patients with teratozoospermia.

The human microbiome in sickness and in health

The study of the human microbiome has led to an exceptional increase in the current understanding of the importance of microbiota for health throughout all stages of life. Human microbial colonization occurs in the skin, genitourinary system and, mainly, in the oral cavity and intestinal tract. In these locations, the human microbiota establishes a symbiotic relationship with the host and helps maintain the physiological homeostasis. Lifestyle, age, diet and use of antibiotics are the main regulators of the composition and functionality of human microbiota. Recent studies have indicated the reduction in microbial diversity as one of the contributors to the development of diseases. In addition to phylogenetic diversity studies, further metagenomic studies are needed at the functional level of the human microbiome to improve our understanding of its involvement in human health.

Semen quality and total microbial load: An association study in important Indian Goat breeds during different seasons

The invasion of the male urogenital tract by microorganisms, and its subsequent effects on sperm fertilising ability, has not been well discussed in bucks. The present study was conducted to assess the bacterial load in fresh semen of the 2-6 years old bucks. For conducting the experiment, semen ejaculates from 18 bucks (6 from each breed namely Jakhrana, Jamunapari and Barbari) were used. We collected 5 ejaculates from each buck in each season (Summer-April to June, Rainy-July to Sept and Winter-November to January). Semen was collected with the artificial vagina (AV) method, and separate AV was used for each buck every time. The semen collection frequency was once in a week. Immediately after initial evaluation, collected semen samples were transferred to the microbiology laboratory of the institute. Thereafter, the semen samples were subjected to bacteriological examination to assess the microbial load. The results of the current study indicate that the microbial load in the semen was significantly (p < 0.05) higher in the Jamunapari bucks and in aged bucks. Bacteriospermia in different seasons was not significantly varied; however, nonsignificant increase in microbial load during the rainy season was observed. Overall, the average bacterial load in the semen of Jamunapari, Barbari and Jakhrana bucks was found 540.50 ± 55.88 CFU/ml, 391.81 ± 46.33CFU/ml and 388.93 ± 44.71 CFU/ml respectively. No significant difference in bacterial counts in the subsequent ejaculates among bucks was observed. Moreover, correlation analysis revealed that the proportions of motility, viability, plasma membrane integrity and acrosomal integrity were negatively influenced by the increased bacterial contamination of buck semen.

Functional and Taxonomic Dysbiosis of the Gut, Urine, and Semen Microbiomes in Male Infertility

BACKGROUND

Little is known about the role of the genitourinary and gastrointestinal microbiota in the pathogenesis of male infertility.

OBJECTIVE

To compare the taxonomic and functional profiles of the gut, semen, and urine microbiomes of infertile and fertile men.

DESIGN, SETTING, AND PARTICIPANTS

We prospectively enrolled 25 men with primary idiopathic infertility and 12 healthy men with proven paternity, and we collected rectal swabs, semen samples, midstream urine specimens, and experimental controls.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We performed comprehensive semen analysis, 16S rRNA sequencing for quantitative high-resolution taxonomy, and shotgun metagenomics with a median of 140 million reads per sample for functional metabolic pathway profiling.

RESULTS AND LIMITATIONS

We identified a diverse semen microbiome with modest similarity to the urinary microbiome. Infertile men harbored increased seminal α-diversity and distinct β-diversity, increased seminal Aerococcus, and decreased rectal Anaerococcus. Prevotella abundance was inversely associated with sperm concentration, and Pseudomonas was directly associated with total motile sperm count. Vasectomy appeared to alter the seminal microbiome, suggesting a testicular or epididymal contribution. Anaerobes were highly over-represented in the semen of infertile men with a varicocele, but oxidative stress and leukocytospermia were associated with only subtle differences. Metagenomics data identified significant alterations in the S-adenosyl-L-methionine cycle, which may play a multifaceted role in the pathogenesis of infertility via DNA methylation, oxidative stress, and/or polyamine synthesis.

CONCLUSIONS

This pilot study represents the first comprehensive investigation into the microbiome in male infertility. These findings provide the foundation for future investigations to explore causality and identify novel microbiome-based diagnostics and therapeutics for men with this complex and emotionally devastating disease.

PATIENT SUMMARY

We explored the resident populations of bacteria living in the gut, semen, and urine of infertile and fertile men. We found several important bacterial and metabolic pathway differences with the potential to aid in diagnosing and treating male infertility in the future.

Flujo vaginal y semen: La microbiota de las relaciones sexuales

Durante las relaciones sexuales, se da el intercambio de especies bacterianas entre las parejas, siendo las relaciones sexuales un factor crucial en la modificación de la microbiota genital. En el presente artículo de reflexión, se analizó el efecto de las relaciones sexuales sobre el intercambio de la microbiota vaginal y seminal. Las parejas que sostienen relaciones sexuales sin protección comparten especies bacterianas que podrían influir negativamente o positivamente sobre los parámetros seminales, como los Lactobacillus con potencial probiótico para el mantenimiento de la calidad del semen.

Role of Lactobacillus in Female Infertility Via Modulating Sperm Agglutination and Immobilization

Infertility has become a common problem in recent decades. The pathogenesis of infertility is variable, but microbiological factors account for a large proportion of it. Dysbiosis of vaginal microbiota is reportedly associated with female infertility, but the influence of normal vaginal microbiota on infertility is unclear. In this review, we summarize the physiological characteristics of the vaginal tract and vaginal microbiota communities. We mainly focus on the bacterial adherence of vaginal Lactobacillus species. Given that the adherent effect plays a crucial role in the colonization of bacteria, we hypothesize that the adherent effect of vaginal Lactobacillus may also influence the fertility of the host. We also analyze the agglutination and immobilization effects of other bacteria, especially Escherichia coli, on ejaculated spermatozoa, and speculate on the possible effects of normal vaginal microbiota on female fertility.

Lactobacillus iners and gasseri, Prevotella bivia and HPV Belong to the Microbiological Signature Negatively Affecting Human Reproduction

Infertile couples undergoing the use of assisted reproductive technology are a good study model to evaluate the microbiological signatures affecting reproductive health. We tested vaginal lavages, follicular fluids, embryo culture mediums, and seminal fluids from 47 couples for their microbiome composition and HPV infection. Twenty-five infertile couples were diagnosed with unexplained infertility, whereas 22 were diagnosed with explained infertility. Lactobacilli were dominant in the vaginal lavages of both patient groups, and the most abundant species was L. iners (CST III), which is linked to a decreased fertility rate. Besides this, L. gasseri—which is known to be associated with oocyte DNA fragmentation and decreased sperm mobility—was identified in the seminal fluids, follicular fluids, and embryo culture media of the unexplained infertility group. Prevotella was increased in the seminal fluids of the explained infertility group, along with HPV-positive seminal fluids: an infection commonly associated with infertility, especially male infertility. Prevotella has been described to negatively affect sperm motility. Taken together, these results suggest that the profiling of the reproductive tract microbiome can add new perspectives to human reproduction.

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.

Selfish genetic elements and male fertility

Selfish genetic elements (SGEs) are diverse and near ubiquitous in Eukaryotes and can be potent drivers of evolution. Here, we discuss SGEs that specifically act on sperm to gain a transmission advantage to the next generation. The diverse SGEs that affect sperm often impose costs on carrier males, including damaging ejaculates, skewing offspring sex ratios and in particular reducing sperm-competitive success of SGE-carrying males. How males and females tolerate and mitigate against these costs is a dynamic and expanding area of research. The intense intra-genomic conflict that these selfish elements generate could also have implications for male fertility and spermatogenesis more widely. This article is part of the theme issue 'Fifty years of sperm competition'.

The semen microbiome and its impact on sperm function and male fertility: A systematic review and meta-analysis

BACKGROUND

Male factor is attributable in up to 50% of cases of infertility. In vitro studies demonstrate that bacteria can negatively impact sperm function. The use of next-generation sequencing techniques has provided a better understanding of the human microbiome, and dysbiosis has been reported to impact health. Evidence regarding the impact of the semen microbiome on sperm function and fertility remains conflicting.

MATERIALS AND METHODS

A systematic search was conducted in accordance with the Preferred Reporting Items for Reviews and Meta-analysis (PRISMA) statement. The databases MEDLINE, OVID and PubMed were searched to identify English language studies related to the identification of bacteria in the semen of infertile and fertile men, between 1992 and 2019. Fifty-five observational studies were included, with 51 299 subjects. We included studies identifying bacteria using next-generation sequencing, culture or polymerase chain reaction.

RESULTS

The semen microbiome was rich and diverse in both fertile and infertile men. Three NGS studies reported clustering of the seminal microbiome with a predominant species. Lactobacillus and Prevotella were dominant in respective clusters. Lactobacillus was associated with improvements in semen parameters. Prevotella appeared to exert a negative effect on sperm quality. Bacteriospermia negatively impacted sperm concentration and progressive motility, and DNA fragmentation index (DFI; MD: 3.518, 95% CI: 0.907 to 6.129, P = .008). There was an increased prevalence of ureaplasma urealyticum in infertile men (OR: 2.25, 95% CI: 1.47-3.46). Ureaplasma urealyticum negatively impacted concentration and morphology. There was no difference in the prevalence of chlamydia trachomatis between fertile and infertile men and no significant impact on semen parameters. Enterococcus faecalis negatively impacted total motility, and Mycoplasma hominis negatively impacted concentration, PM and morphology.

DISCUSSION AND CONCLUSIONS

Ureaplasma urealyticum, Enterococcus faecalis, Mycoplasma hominis and Prevotella negatively impact semen parameters, whereas Lactobacillus appears to protect sperm quality. These findings may facilitate the development of novel therapies (eg probiotics), although the evidence regarding the impact of the seminal microbiome on fertility is inconclusive and further studies are needed to investigate this association.

Semen microbiota: cluster analysis of real-time PCR data

To this day semen microbiota is still poorly understood, and clinical significance of detecting specific microorganism groups has not been clearly determined. The aim of this work was to conduct cluster analysis of semen microbiota detected using real-time PCR. 634 semen samples of reproductive age men were analyzed using the Androflor kit. Microbial DNA in the quantity of no less than 103 GE/ml was detected in 460 samples (72.5%). From 1 to 14 microorganism groups were detected in 350 samples (55.2%) in the quantities that exceeded the threshold values (the detection rate of specific groups: 3.3–21.0%). In these 350 samples 4 stable microbiota clusters were determined. Each of the clusters was characterized by the prevalence of a specific microorganism group: obligate anaerobes (cluster 1; n = 172; detection rate — 49.1%), Lactobacillus spp. (cluster 2; n = 78; detection rate — 22.3%), gram-positive facultative anaerobes (cluster 3; n = 62; detection rate — 17.7%), Enterobacteriaceae / Enterococcoccus (cluster 4; n = 62; detection rate — 10.9%). Cluster 1 was less stable and was characterized by the larger species diversity compared to other clusters.

Roles of host genetics and sperm microbiota in reproductive success in healthy rabbit

Although the effects of sperm microbiota and sperm quality have been described previously, recent studies provide evidence that female genital modifications triggered by seminal components could be of significant importance to identify some disturbances associated with fertility. So, sperm microbiota could play a key role in sperm quality, contributing to fertilisation. To understand how sperm microbiota diversity is influenced by the host genetics, the symbiotic bacteria in four inbred lines raised in the same animal facility and their effects on sperm quality and fertility were analysed. Forty healthy rabbits from four selected Spanish commercial lines were used in this research (three based on litter performance, designated A, V and LP, and one selected for daily body weight gain, called R). Significant variations in the seminal concentration, morphology and some motion parameters were found among inbred lines, but sperm motility and viability were similar among inbred lines. After mating, inbred lines selected for litter size had the same fertility rate, significantly higher than inbred line selected for body weight (82 ± 3.3%, 79 ± 3.5% and 89 ± 4.5% versus 61 ± 3.7%, for the A, V and LP vs R lines, respectively, p < 0.05). Bacteria belonging to Proteobacteria, Firmicutes, Fusobacteria and Bacteroidetes were identified in sperm microbiota. At genus level, the bacterial community composition in the sperm microbiota was influenced by host genetics. A total of 35, 16, 34, and 51 genera were accurately detected in the A, V, LP, and R lines, respectively. Moreover, Enhydrobacter, Ferruginibacter, Myroides Paracoccus, Rheinheimera, Tepidiphilus, Tetradesmus obliquus and Thauera genera were present only in the inbred lines selected for litter size. Moreover, the discriminant analysis revealed Lysinibacillus and Flavobacterium genera as potential biomarkers for fertility. Thus, these two genera may play a key role in fertility. Our results demonstrated the existence of a rabbit inbred line-specific variation in bacterial occurrence in sperm microbiota. Moreover, fertility differentials among inbred lines that were not predicted by routine semen analysis could be partly explained by the symbiotic state of the semen microbiota.