Women taking the drugs had fewer UTIs over the next year than those taking cranberry capsules, but they also built up resistance to the antibiotics.
When it comes to antibiotics for UTIs, there's a really important need here to look for alternatives and to reconsider both what we've done in terms of treatment and prophylaxis," said Dr Betsy Foxman, an epidemiologist at the University Of Michigan School Of Public Health in Ann Arbor who didn't participate in the new research.
Cranberries have long been thought to help prevent UTIs through anecdotal evidence, she told Reuters Health, but it's not clear how they might work, and rigorous studies have shown mixed results.
How TMO-SMX differs from Cranberry capsules
The authors of a report in Archives of Internal Medicine say while UTIs usually resolve on their own, they're often treated with antibiotics to ease the symptoms and to prevent rare complications. Sometimes they're prescribed prophylactically, because "the longer you can go without having one, the more likely it is that you'll never have another one," Dr Foxman said.
In the new study, Dr Marielle Beerepoot of Amsterdam's Academic Medical Centre randomly assigned 221 premenopausal women with at least three UTIs in the past year to take trimethoprim-sulfamethoxazole (TMP-SMX) or cranberry capsules each day.
After one year, women taking the antibiotic had reported an average of close to two UTIs, compared to four in the cranberry group. On average, women got their first new infection eight months after starting TMO-SMX, vs four months into taking cranberry capsules.
One woman taking the antibiotics had a serious reaction to them.
Give antibiotics for treatment to decrease the risk
Resistance to TMP-SMX – and some similar antibiotics – also shot up in the antibiotic group within one month.
"My concern is this, UTI is one of the most common bacterial infections," Dr Foxman said. "When you give antibiotics even for a short duration on a large scale, you definitely push towards antibiotic resistance."
When the drugs are given for prevention and not just for treatment, that risk of resistance increases, she said.
Cranberry juice may help
In women in the study taking antibiotics, resistance levels did return to normal a few months after they stopped taking the drugs.
Dr Foxman said women with recurrent UTIs and their doctors should have a conversation about preventing the infections, taking issues such as antibiotic resistance into consideration.
The question, she said, is whether the patient feels so miserable that she really needs them, or whether she'd want to go to alternatives first.
But "certainly, taking cranberry juice is not going to hurt, and it may help," she said.
The resistance in antibiotic is a big problem
Dr Bill Gurley from the University of Arkansas for Medical Sciences in Little Rock told Reuters Health that one issue with these studies is that the cranberry doses used may be too low to be effective for UTI prevention. However, the best dose of the active ingredients in cranberries has yet to be figured out, he wrote in a commentary published with the study.
The take-home message, Dr Beerepoot told Reuters Health, "is that cranberries are less effective than the antibiotics, but antibiotic resistance is a big problem." Other studies have pointed to a possible benefit of cranberry juice or extract, she said without serious side effects.
"Maybe therefore cranberries can be an alternative for those women who don't want to take antibiotics" because of resistance worries, she said.
(Reuters Health, July 2011)