Antibiotics are still better than probiotics at preventing urinary tract infections, but at least "good bacteria" don't add to a person's antibiotic resistance, a new study concludes.
Recurring UTIs are common among some women and low-dose antibiotics are sometimes used to prevent them. The worry is that overuse of the drugs also reduces their effectiveness by making disease-causing bacteria like E. coli resistant.
"This is an increasing worldwide problem, resulting into less and less treatment options for (severe) bacterial infections in all countries of the world," Dr. Suzanne Geerlings, from the Academic Medical Center at the University of Amsterdam in The Netherlands and one of the new study's authors, wrote in an email to Reuters Health.
Geerlings and her colleagues recruited 252 women between January 2005 and September 2007 for a trial to compare the use of antibiotics and probiotics to prevent UTIs.
The participants, who lived in communities surrounding the medical center, were all postmenopausal -- a time when vulnerability to UTIs increases because of hormonal changes, according to the researchers.
All the participants reported having had at least three UTIs in the year before the trial began, and the average number was seven.
The women were separated into two groups of about the same size. One group took a single dose of the antibiotic co-trimoxazole (Bactrim, Septra and others) every day for twelve months, while the other group took two capsules containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, both types of beneficial bacteria, daily.
All the participants also took placebo pills so the patients and the people dispensing the pills wouldn't know who received which treatment -- to minimize any influence on the study's results.
The researchers then tracked how many UTIs occurred in each group of women over a year. They also collected vaginal swabs and samples of the women's urine and feces every month to test for the presence of good bacteria and infection-causing bacteria like E. coli.
In addition, women took a monthly survey asking about symptoms of UTIs, side effects, other infections and antibiotic use.
Overall, the antibiotics were slightly better at keeping UTIs at bay.
About 69 percent of the women in the group taking the antibiotic had one or more UTIs within the year. On average, the antibiotic group had 2.9 UTIs per woman.
As for the probiotic group, about 79 percent had a UTI within the year, with an average of 3.3 UTIs per woman.
The women taking the antibiotic also seemed to go twice as long without a UTI -- six months, compared with three months among women taking the probiotics.
Based on the women's urine and feces samples, however, resistance to a range of antibiotics seemed to increase within the first month in the antibiotic group.
Before the study, about 20 percent to 40 percent of E. coli in samples from all the women's bodies were resistant to co-trimoxazole.
At the 12-month mark, between 80 percent and 95 percent of the bacteria were resistant in the women taking the antibiotic.
Rates of resistant E. coli were slightly lower at 12 months in women taking the probiotics than when the study began.
Similar changes in antibiotic resistance were seen for a range of other antibiotics, including ciprofloxacin and gentamicin, among both groups of women -- which the researchers speculate might be because the same mechanism in certain bacteria allows them to resist several different drugs.
The absence of increased resistance among women taking the probiotics means that "lactobacilli may be an acceptable alternative for prevention of UTIs, especially in women who dislike taking antibiotics," the researchers wrote in the Archives of Internal Medicine.
The study, however, had several limitations.
More than 80 women dropped out of the study by the end of the year because of side effects and other reasons. A greater number of those taking the probiotics had diarrhea compared to those taking the antibiotics, for instance. Other reasons for dropping out included the participant not thinking the treatment was working, or she couldn't adhere to study's directions.
As a result, the researchers did not have the number of participants in each group they would have liked to give the findings statistical weight.
Despite the study's weaknesses, a commentary published in the same journal called the findings "exciting and compelling."
"I think we need to appreciate that the normal flora in our body is another system we need for good health and antibiotics disrupt it and leave lasting effects… We need to think of antibiotics as a situation that has some risk," Dr. Barbara Trautner, one of the commentary's authors, told Reuters Health.
Trautner, of the Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine in Houston, said that probiotics may be an acceptable alternative but they need further exploration.
Topical estrogen creams are sometimes used to prevent UTIs in menopausal women, but many women prefer to avoid using hormones.
In her commentary, Trautner wrote that 60 percent of women in the United States experience UTIs or bladder infections during their lifetimes, and they recur in about a third of those women.
"We don't have terrific preventive strategies so a probiotic approach would be beneficial and promising," Trautner said.
For right now, she said most women with recurring UTIs have exhausted any type of behavioral changes that might help prevent the infections, and are left with low-dose antibiotics as their only recourse.