Hormone replacement therapy (HRT) might be able to break the cycle of recurring urinary tract infections in some women, a new study reports.
Women taking HRT for symptoms of menopause tend to have a greater variety of bacteria in their urine, including larger amounts of the healthy Lactobacillus-type bacteria known to protect against urinary tract infections (UTIs), researchers report.
In women who aren't suffering a UTI, "we basically found that the strongest variable that was associated with having these beneficial bacteria present was the fact they were taking estrogen therapy," said senior researcher Nicole De Nisco. She's an assistant professor of biological science with the University of Texas at Dallas.
For this study, De Nisco and her colleagues performed genetic analysis on all bacteria found in the urine of 75 postmenopausal women who'd gone to the UT Southwestern Medical Center's Urology Clinic for treatment.
The women were evenly divided into three groups: those who'd never had a UTI; those who'd had recurrent infections in the past; and those who were currently infected and had been before.
The women with recurrent infections tended to have fewer types of bacteria in their urine, the researchers found. In fact, women who didn't have recurrent UTIs had a 10-fold greater variety of bacteria.
Further, about half of the women were taking hormone therapy for menopause symptoms, and those women tended to have more Lactobacilli in their urine, the results showed.
Hormone therapy delivered via pills or a patch appeared to promote Lactobacilli growth more than vaginal cream, the researchers said.
"Estrogen stimulates our vaginal cells to produce more of these kinds of carbohydrates that Lactobacilli really like to eat," De Nisco said, describing one theory why hormone therapy might promote healthy vaginal bacteria. "Basically, estrogen makes our cells make more food for the Lactobacilli," she explained.
The results suggest that hormone therapy might be a potential treatment for recurring UTIs in women, although it should first be tested in a rigorous clinical trial, De Nisco said.
"Maybe after they complete their antibiotic course, they would then get a probiotic and then take that along with HRT for a very limited period of time, until the Lactobacilli are able to colonize the urinary tract," De Nisco said. "It's not necessarily something to be a long-term thing."
The study clearly shows the advantage of using DNA analysis rather than traditional cultures in testing a woman's vaginal health, said Dr. Elizabeth Kavaler, a urology specialist with Lenox Hill Hospital in New York City.
"DNA testing of the urine will surely replace traditional cultures because of its accuracy and appreciation of the urinary microbiome," Kavaler said.
However, Kavaler agreed that it's too soon to start using hormone therapy to stop recurring UTIs.
"This study does not support the use of HRT in the prevention of UTIs in postmenopausal women," Kavaler said. "Other studies have looked at vaginal estrogen use in an effort to reduce UTIs, but even that data is inconclusive."
Studies have indicated female hormone therapy could increase risk of heart disease and breast cancer, but only with combination estrogen-progestin therapy.
Because of the coronavirus pandemic, these results were presented July 17 at a virtual meeting of the European Association of Urology. Data and conclusions presented at meetings should be considered preliminary until peer-reviewed for publication in a medical journal.
The U.S. National Library of Medicine has more about the benefits and risks of hormone therapy.