Penis microbes may play role in common vaginal infection, study finds

Microbes on a male’s penis may be playing a role in the transmission of bacterial vaginosis (BV), according to a new study published in the journal Frontiers in Cellular and Infection Microbiology.

The researchers found that not only was the bacteria related to BV found in the microbes of male penises, but its presence also was a high predictor of a female sex partner having the infection.


BV affects nearly 30% of women ages 14-49 and is the most common infection in women 15-44. The infection develops when an imbalance of the “good” and “harmful” bacteria normally present occurs in the female’s vagina, according to the Centers for Disease Control and Prevention(CDC). If a pregnant woman is infected, it can cause premature labor or low birth rates. Women with BV are also at higher risk for contracting HIV or other sexually transmitted infections such as gonorrhea and chlamydia, both of which can lead to pelvic inflammatory disease.

Health experts say the risk for bacterial vaginosis can occur when there is a new sex partner or multiple partners, or with hygiene practices like douching. The CDC says symptomatic females may complain of pain, itching or burning in or around the vagina, burning during urination, and a strong fish-like odor, especially after sex. Recurrence is also a common complaint, health experts told Fox News.

“I was in and out of the gynecologist’s office every two to three months,” Mary, one patient who has suffered from BV, told Fox News. She asked for her last name to be withheld for privacy reasons.

The researchers found that not only was the bacteria related to BV found in the microbes of male penises, but its presence also was a high predictor of a female sex partner having the infection.

“It became frustrating to suffer from this pain and irritation. I tried different treatments, including Metrogel, even boric acid suppositories, [but] nothing seemed to make it ever go away. I asked my doctor if it could be transmitted between my partner and me and if he could be treated. She said there was no real proof that treating my partner would be effective.”

The new study could offer hope for women like Mary.

“This study also reminds us that BV is sexually transmissible and may explain why it is difficult to clear with topical and oral antibiotics – there is often reinfection or re-inoculation between partners,” Dr. Anna Powell, from the Department of Gynecology and Obstetrics at Johns Hopkins University School of Medicine, told Fox News.

“As a gynecologist who cares for many women with BV and other vaginitis concerns, I hear the frustration that accompanies this chronic and often relapsing condition. In my own practice I have counseled patients that there is still much we don’t know about sex partner treatment to help relieve the index partner’s symptoms,” she said.

The physician, who is also a member of the American College of Obstetricians and Gynecologist, added: “I would tell them this study certainly provides validation to the idea that both partners are involved, i.e. it’s not just something the female partner is [or] isn’t doing.”

“Male sex partner treatment may be a new strategy,” Dr. Supriya Mehta, an epidemiologist at the University of Illinois at Chicago and author of the study, stated in multiple reports.

“I would like for clinicians, researchers and the public to be inclusive of male sex partners in their efforts to improve women’s reproductive health,” Mehta added.


The study found BV occurred in 31% of the 168 couples studied, where the woman did not have BV at baseline, and 37.3% if the man was uncircumcised and 26.3% who were.

“Baseline penile microbiota accurately predicted BV incidence in women who did not have BV at baseline, with more than half of incident infections observed at 6 to 12 months after penile microbiome assessment. These results suggest interventions to manipulate the penile microbiome may reduce BV incidence in sex partners, and that potential treatment (antibiotic or live biotherapeutic) will need to be effective in reducing or altering bacteria at both the glans/coronal sulcus and urethral sites,” the authors stated.

“While we can’t draw firm conclusions on the exact antibiotic or pro-biotic regimen/duration, this study highlights that, yes, penile skin appears to be a reservoir for the bacteria that are associated with BV in women,” Powell told Fox News, adding that there were limitations to the study and further research should be done to investigate these new findings.