• Posted August 4, 2026

Bacterial Vaginosis Tied To Tripled STI Risk, Major Study Finds

Women with vaginosis are around three times as likely to also test positive for gonorrhea, chlamydia or other bacterial sexually transmitted infections, a new study says.

The study results confirm guidance from the U.S. Centers for Disease Control and Prevention that women being treated for bacterial vaginosis should be tested for STIs, which can present with similar symptoms, researchers said in the journal O&G Open.

"STIs can lead to serious reproductive and other health complications when left undetected and untreated,” senior researcher Dr. Damian Alagia said in a news release. 

“We hope our new data inspires much-needed additional research on this clinical area while also reinforcing for clinicians and policy makers the value of a comprehensive diagnostic approach that considers STI testing for patients with bacterial vaginosis," Alagia said. He is the senior medical director of women’s health at Quest Diagnostics, headquartered in Secaucus, New Jersey.

Bacterial vaginosis (BV) is one of the most common gynecologic problems among women, with nearly 30% experiencing the condition at some point in their life, researchers said in background notes.

Vaginosis happens when the natural bacteria that help keep the vagina healthy become out of balance. Symptoms can include vaginal discharge, a foul-smelling odor, itching, and burning during urination, according to the Mayo Clinic.

Vaginosis is more common among women who are sexually active, but its link to increased risk for STIs has been relatively unexplored, researchers said.

"BV is one of the most common health problems in women, and yet research in this area of women's healthcare is sadly lacking,” Alagia said.

For this new study, researchers evaluated data for more than 1.5 million women ages 15 or older with a suspected vaginal condition for whom Quest Diagnostics analyzed samples.

Among all the women, nearly 39% were positive for bacterial vaginosis and 29% for a fungal yeast infection, results showed. About 11% were positive for both.

About 12% of the women with bacterial vaginosis had at least one STI, compared to fewer than 4% of women without the condition.

After adjusting for other factors, having bacterial vaginosis was linked to:

• 3.8 times greater odds of gonorrhea

• 2.8 times higher risk for chlamydia

• 3.6 times higher odds for trichomoniasis

• 1.9 times higher risk for mycoplasma genitalium

By comparison, having a yeast infection was not linked to an increased risk for STIs.

"This research confirms and expands on previous research on increased STI risk in women with BV, but with the advantage of a much larger data set from which to draw conclusions," senior researcher Elizabeth Marlowe said in a news release.

"This large study underscores the value of comprehensive molecular testing when clinically indicated, enabling clinicians to detect coinfections from a single specimen, optimize patient management, and strengthen evidence-based care,” Marlowe said. She is executive director for infectious disease at Quest Diagnostics.

More information

The Mayo Clinic has more on bacterial vaginosis.

SOURCES: Quest Diagnostics, news release, June 30, 2026; O&G Open, August 2026