The excess of some strains of Pseudomonas, Prevotella and Lactobacilli in the seminal fluid “would be able to alter the concentration of spermatozoa, favoring an inflammatory micro-environment, an enemy of male fertility”. This is demonstrated by two reviews conducted by researchers from the University of Naples ‘Federico II’, together with Brazilian and Danish colleagues, and by experts from the University of Padua, recently published in ’Frontiers in Endocrinology’ and ‘Cells’. From the two works, which took into consideration 37 research studies and 27 studies respectively, it emerged that “an increase in Prevotella and Pseudomonas strains and an increase in Lactobacillus iners are risk factors for the sperm concentration in the seminal fluid, causing a reduction below the established minimum threshold” by the World Health Organization and necessary for male fertility.
The experts of the Italian Society of Andrology (Sia), on the occasion of the VI Congress Nature, Environment, Man (Nau) being held today and tomorrow in the Langhe, will focus attention on this theme of primary importance, as “it is estimated that a reduced number of sperm is the cause or contributing cause of at least 30% of cases of couple infertility – recalls Sia - There are in fact numerous studies that have found that in the last 50 years there has been a significant global decline of concentration and total sperm count, the number of which has halved in recent decades and whose rate of reduction has more than doubled since 2000”.
“It was once believed that semen was naturally free of bacteria; any microbe found among the sperm was considered a sign of infection. But the most recent research, although still in its initial phase, is now demonstrating that sperm has its own microbial community, just as for example already identified for the intestine and vagina – explains Alessandro Palmieri, president of Sia and professor of Urology at Federico II University of Naples -. The sperm microbiome can contain a large set of microbes, with the majority originating from glands in the upper reproductive tract, including the testes, seminal vesicles, and prostate. These bacteria, if in balance, work for our well-being, but if in excess they could have a potential role in infertility.”
“The alteration of the female reproductive microbiome has long been associated with reduced or negative pregnancy outcomes, but now more and more studies are highlighting how even men who present alterations in optimal sperm physiology have a different composition of the microbiota compared to fertile individuals and how this may be associated with conditions of oligozoospermia, when male sperm contains a lower number of spermatozoa than normal – underlines Palmieri – In particular, the analysis in which researchers from the University of Naples participated ‘Federico II’, which took into consideration 37 studies conducted between 1980 and 2023 on over 9300 men, found an excess of Prevotella and Lactobacillus strains in individuals with reduced sperm count, compared to men with normal sperm counts. Results confirmed by the review conducted by researchers from the University of Padua, on 27 works collected on the ‘PubMed’ platform up to 2023, which identified also the presence of high concentrations of Pseudomonas strains. Research has found that, especially excess Lactobacillus, can produce lactic acid, potentially leading to a local inflammatory environment that can negatively affect sperm count.”
“The data that is accumulating, and the level of evidence in this field, is certainly constantly growing, but the study of the microbiota of seminal fluid still represents a neglected aspect of diagnostics dedicated to the analysis of male infertility. However, it has great potential in improving the understanding of the so-called ‘idiopathic’ or ‘sine causa’ forms – underlines President Sia -. This knowledge could change treatments and pave the way for new therapeutic strategies to correct alterations in sperm parameters and improve male fertility”, concludes Palmieri.
Interview: Exploring the Microbial Impact on Male Fertility
Editor (Time.news): Welcome to our exclusive interview with Professor Alessandro Palmieri, the esteemed president of the Italian Society of Andrology and a professor of Urology at Federico II University of Naples. Professor Palmieri, thank you for joining us today.
Professor Palmieri: Thank you for having me. It’s a pleasure to discuss this important topic.
Editor: Your recent research collaboration highlighted some alarming findings regarding the presence of microbes in seminal fluid. Can you elaborate on what your studies indicated about these bacterial strains and male fertility?
Professor Palmieri: Certainly. Our findings, derived from two comprehensive reviews, showed that excess strains of Pseudomonas, Prevotella, and Lactobacillus in the seminal fluid can negatively impact sperm concentration. These bacteria can create an inflammatory micro-environment that is detrimental to male fertility.
Editor: That sounds quite significant. So, how specifically do these bacteria lead to a reduction in sperm concentration?
Professor Palmieri: The presence of these bacteria affects the balance of the sperm microbiome. While it was traditionally believed that semen was sterile, we’re now learning that it has its own microbial community. When certain strains dominate, they can disrupt sperm physiology and lower sperm concentration below the minimum threshold determined by the World Health Organization.
Editor: That’s a fascinating shift in understanding. You mentioned that a reduced number of sperm is increasingly linked to infertility issues. Can you share more about the broader implications of these findings?
Professor Palmieri: Yes, of course. An estimated 30% of couples facing infertility issues may be experiencing reduced sperm counts. Our studies indicate that over the past 50 years, global sperm concentration has halved, and the rate of decline has accelerated, particularly in the last two decades. This decline underscores the importance of understanding the microbiome not only in female reproductive health but in men’s health as well.
Editor: The connection between microbiomes and reproduction is truly groundbreaking. How does this shift in perspective shape future research and clinical practices?
Professor Palmieri: This approach opens up new avenues for research, especially in identifying and potentially modulating microbial populations to support fertility. It suggests that personalized treatments could be developed based on individual microbiome profiles. Understanding the delicate balance of these microbial communities may help in both prevention and treatment of infertility in men.
Editor: That’s incredibly promising. Are there any recommendations you would make to men concerning their reproductive health in light of these findings?
Professor Palmieri: Maintaining overall health is crucial. A balanced diet, regular exercise, and avoiding factors that can harm reproductive health—such as smoking and excessive alcohol consumption—are important. Furthermore, awareness of potential infections and the health of the reproductive system should be priorities for men.
Editor: It’s clear that a well-rounded approach to health can have significant benefits. Do you think public awareness around male fertility and microbiomes needs to change?
Professor Palmieri: Absolutely. For too long, discussions about fertility have predominantly focused on women. It’s essential to foster a better understanding of male fertility, including how microbial health plays a role. Initiatives to educate the public and healthcare providers can lead to better outcomes for both men and women.
Editor: Thank you, Professor Palmieri, for shedding light on this crucial aspect of male fertility. It’s certainly a complex field with vast implications for health and well-being.
Professor Palmieri: Thank you, it’s been a pleasure. I hope our findings will inspire further research and awareness in this critical area.
Editor: We appreciate your insights and look forward to following this important research. Thank you for joining us today.