Testes 'Microbiome' Discovery Could Lead to Better Male Infertility Treatments

Open a medical textbook and you might learn that the inside of a man's testes are sterile environments, free of bacteria.

New research suggested that this common belief is incorrect, and that the inside of men's testes have a unique microbiome that may have a direct link to fertility. This finding could lead to new therapies for treating men who have trouble producing sperm and who might otherwise not be able to have a biological child.

"These findings are actually surprising," Massimo Alfano, a senior scientist at the Urological Research Institute at the IRCCS Hospital San Raffaele in Milan, told the news website Live Science.

Models of sperm. Scientists discovered that the male testes have a microbiome that could affect fertility. Getty Images

A study Alfano's team published in the journal Human Reproduction showed that men who have a condition called azoospermia, which causes them to have no measurable sperm in their semen, might have a less diverse population of microbes living in their testes.

So far, the only treatment for the most severe form of azoospermia, caused by poor sperm production, is surgery to harvest the sperm from the testicular tissue. This surgery is not always successful, and researchers found that the less diverse a microbiome, the more likely the surgery will fail. That could potentially help doctors avoid unnecessary surgery in the future, Dr. Sarah Vij, a urologist at the Cleveland Clinic told Live Science.

"If the microbiome can enable us to predict who is going to have success, we could probably spare some men surgery," she said.

The research could have a far-reaching impact, since as many as 9 percent of men of reproductive age in the United States have some fertility problems, and of those, a complete lack of sperm occurs in about 10 to 15 percent of cases, according to the National Institutes of Health, a government medical research center headquartered in Maryland.

For the study, researchers looked at the testicular tissue from 10 men with poor sperm production caused by azoospermia, as well as testicular tissue from five men who produced normal amounts of sperm.

The study found that the men with azoospermia had more bacteria overall in their testes, but their testicular microbiome was less diverse.

The findings are preliminary and more research is needed, but it is possible that as scientists learn more about the testicular microbiome, it could help guide future therapies for men and give them more options for treating infertility besides surgery, Vij said.