New research finds that the bacteria that causes a common vaginal infection can also have a major presence in men and can be sexually transmitted.
“We looked at the urethral microbiome of healthy adult men and found that many of them actually had bacteria that is associated with bacterial vaginosis in women,” says David Nelson, professor of microbiology and immunology at the Indiana University School of Medicine and co-corresponding author of the study.
“These bacteria can be transmitted through heterosexual, vaginal sex, something that has never been shown in research before.”
Bacterial vaginosis is a common condition in women, but until now, researchers have not confirmed it can be transmitted via sex. Many scientists previously thought urine is sterile, Nelson says.
But the new study, published in Cell Reports Medicine, proves that is not the case. The team looked at 110 distal urethral swab specimens from men with no urogenital symptoms, no sexually transmitted infections (STIs), and no inflammation of the urethra.
“What we found was stunning,” Nelson says. “These men had two types of colonized bacteria—one that was native to the penile urethra, and one that was from an outside source. This is the first time it has been shown that the human microbiome is primarily shaped by behavior.”
The researchers found only the men who reported having vaginal sex carried the bacteria often associated with bacterial vaginosis. They also discovered the bacteria was detectable for at least two months after having vaginal sex.
The discovery could lead to sweeping changes in how men and women are treated for certain STIs, including bacterial vaginosis, by doing more contact tracing to treat sexual partners better, Nelson says.
“Our research provides the first healthy baseline for clinicians and scientists to compare with diseased urogenital states,” says lead author Evelyn Toh, assistant research professor of microbiology and immunology.
“Having established this baseline, we may be able to offer new insights into bacteria’s role in urogenital diseases. There is still stigma in talking about sex, and hence STIs are often overlooked. However, STIs really impact women and minorities disproportionately, as well as socioeconomically disadvantaged people.”
While this study shows women can transmit bacterial vaginosis to men, they’re now studying whether men could transmit it to women as well.
Additional coauthors are from the University of Alabama, Birmingham; Loyola University Chicago; and Indiana University.
Source: Indiana University