Antibiotics might not be the surefire solution for urinary tract infections …

Urinary tract infections (UTIs) are the one of the most common types of infection in women, affecting more than 50% of women at some point during their lifespan. Characterized by abdominal pain and pressure, a nearly constant feeling that you need to pee, and (the most trademark and terrible UTI symptom, speaking from experience) a burning feeling when urinating.

Thanks to our unique physiology—specifically a short urethra that makes it easier for bacteria to enter the urinary tract—women are a whopping 30 times more likely than men to be diagnosed with this common infection, according to the Department of Health and Human Services Office on Women's Health.

A round of antibiotics is the most common course of treatment, and usually clears up the symptoms … temporarily. Once UTIs start, it's tough to stop them: 25 to 40% of women who get a UTI will have at least one more within six months, according to one 2016 study.

Since they're oh-so common, frequently recur and can spread to the kidneys and cause serious damage, scientists are on a mission to figure out why some women may get stuck in a vicious cycle of infection-antibiotics-infection-antibiotics. Turns out that Rx might make it easier for our bodies to fall victim to another infection.

person holding their abdomen on a couch
Credit: Getty Images E+

What This Gut Health Research Found

A study published May 2 in Nature Microbiology found that the answer to getting out of this painful loop might be hiding in our guts: A course of antibiotics eliminates the disease-causing bacteria from the bladder, true, but not from the intestines. Antibiotics can kill off the good gut bacteria in the microbiome, allowing the surviving bacteria to have free rein to multiply and spread to the bladder once more—where the UTI might begin again.

To determine this, researchers studied urine, blood and stool samples of 15 women with recurrent UTIs (defined as two in six months or three in one year) and 16 women without. They tracked the amount and types of bacteria in their stool, tested for bacteria in their urine and examined gene expression in their blood samples.

During the one-year study, 24 UTIs were diagnosed—all among those with histories of previous UTIs. The researchers then took additional samples from the women post-diagnosis to add to their database.

UTIs are most often triggered by Escherichia coli bacteria from the intestines that work their way into the urinary tract. Fascinatingly, both of the groups had E. coli strains in their guts that could cause UTIs. But women who have recurrent UTIs tend to have less diverse microbiomes than their UTI-free peers. These women were especially lacking in an impactful type of good bacteria, a short-chain fatty acid called butyrate, which can offer some anti-inflammatory benefits.

With two major gut health defenses down, the invading bacteria had more opportunity to proliferate and infect the urinary tract another time.

"We think that women in the control group were able to clear the bacteria from their bladders before they caused disease, and women with recurrent UTI were not, because of a distinct immune response to bacterial invasion of the bladder potentially mediated by the gut microbiome," Colin Worby, Ph.D., a computational biologist and the paper's lead author, tells the Washington University School of Medicine in St. Louis News.

While this was a small, fairly short-term study, the researchers hope these preliminary findings raise two major red flags:

  1. Antibiotics might not be the best treatment option for all people experiencing UTIs. "Our study clearly demonstrates that antibiotics do not prevent future infections or clear UTI-causing strains from the gut, and they may even make recurrence more likely by keeping the microbiome in a disrupted state," Worby says.
  2. Medical professionals who think it's all about hygiene need to think again. "It's frustrating for people who are coming in to the doctor with recurrence after recurrence after recurrence, and the doctor, who's typically male, gives them advice about hygiene," Scott J. Hultgren, Ph.D., co-senior author and the Helen L. Stoever Professor of Molecular Microbiology at Washington University, adds to the School of Medicine News. "That's not necessarily what the problem is … The problem lies in the disease itself, in this connection between the gut and the bladder and levels of inflammation. Basically, physicians don't know what to do with recurrent UTI. All they have is antibiotics, so they throw more antibiotics at the problem, which probably just makes things worse."

The Bottom Line

Hultgren, Worby and their research partners are diving into alternative ways to potentially eradicate UTI-causing strains of E. coli that still allow the good bacteria to survive and thrive. Two promising medical options: An experimental drug based on the sugar mannose and a possible vaccine. One surefire strategy that they say—and we agree!—certainly can't hurt: eating more probiotic foods and focusing on eating a gut-healthy diet. (By the way, gut health is important even if you don't struggle with UTIs! Research suggests a healthy microbiome can reduce stress and anxiety, aid in weight loss—if that's your aim—support heart health and more.)

Always be sure to talk to your doctor before making a lifestyle change or if you are experiencing symptoms of a UTI. For more on gut health, take a look at the best and worst diets for gut health, then get a jump-start via our 30-day healthy gut challenge.