Probiotics Could Help Prevent Urinary Tract Infections

The diversity of bacteria is represented in this artist rendering. (Image credit: Dreamstime)

Researchers have found a way to limit recurrent urinary tract infections (UTIs) in women by replenishing naturally occurring bacteria that live in the vagina, according to a new study.

Only seven of 50 women who received a probiotic to restore the naturally occurring bacteria during the course of the study experienced a recurrence of UTIs over a 10-week period, compared with 13 of 50 women who received a placebo, the study said.

During a UTI, gut bacteria like E. coli take up residence in the vagina and displace good bacteria, called vaginal lactobacilli, that normally live there, said Dr. Ann Stapleton, professor of medicine at the University of Washington. UTIs cause pain during urination, and can even lead to back pain, fever and bladder and kidney infections.

Women take antimicrobial medications to combat these infections and the medications wipe out all bacteria, both good and bad. But for some women, the bad bacteria grow back to cause a recurrent UTI. The probiotics help to restore the natural bacterial environment to make it hard for the bad bacteria to cause another infection, Stapleton said.

"We know that if we look at people around time of [urinary tract infection] and right before that, these lactobacilli are gone from the vagina," Stapleton told MyHealthNewsDaily. "That's what suggests that replenishing them might stop a urinary tract infection from happening again."

The study was published today (April 15) in the journal Clinical Infectious Diseases, and was funded by the National Institutes of Health.

Preventing UTIs

Stapleton and her colleagues had 50 women use a Lactobacillus crispatus intravaginal suppository probiotic (a small tamponlike device inserted into the vagina) and 50 women use a placebo for five days, and then once a week for 10 weeks. All women experienced recurrent UTIs, a condition that was defined in the study as having one infection in a 12-month period (though most people define recurrence as having two or three infections over a year).

The probiotic did not completely prevent recurrence of UTIs, but it did seem to reduce the number of women who experienced recurrence, the study said.

Fifteen percent of women who received the probiotic had a recurrence of UTIs during the study period, compared with 27 percent of women who took the placebo, the study said.

A common infection

UTIs are the second most common infection in the body and prompt 8.3 million doctor visits every year, according to the National Institutes of Health (NIH). Almost 20 percent of women who experience a UTI will have a recurrence of the infection, and then 30 percent of those women will have a second recurrence.

The infections are caused when bacteria get into the urinary tract by wiping from back to front after a bowel movement (thereby pushing the bacteria closer to the urethra), having sex (where germs already in the vagina can be pushed into the urethra) and waiting too long to urinate (the urine allows a breeding ground for bacteria), according to the NIH.

Researchers aren't completely sure why it is that lack of vaginal lactobacilli seems to be linked with UTIs, but "we think that a variety of processes occur," Stapleton said.

"Maybe [the vaginal lactobacilli] kill off E. coli, or maybe they exist in much higher numbers and stop them from attaching to cells that line the vagina," Stapleton said. "Or, they may inhibit growth of E. coli."

Researchers still need to replicate the study in a larger number of women, and then test the probiotic's effectiveness against current antimicrobial treatments for recurrent UTIs, Stapleton said.

While antimicrobials are effective in preventing the recurrence of UTIs, people have to take them once a day, three times a week or before sexual intercourse, depending on the type of antimicrobial, she said.

The probiotic suppository would "probably be once a week or less frequently, and it takes, like, two seconds," Stapleton said. "It's like putting in a tampon, except much smaller than that. It's a tiny thing, then you forget about it."

Pass it on: Replenishing naturally occurring bacteria to the vagina could help prevent recurrence of urinary tract infections.

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This story was provided by MyHealthNewsDaily, a sister site to LiveScience.

Amanda Chan
Amanda Chan was a staff writer for Live Science Health. She holds a bachelor's degree in journalism and mass communication from the Walter Cronkite School of Journalism and Mass Communication at Arizona State University, and a master's degree in journalism from Columbia University.