SAN FRANCISCO—Antibiotic prophylaxis for recurrent urinary tract infections (UTIs) in postmenopausal women is slightly more effective than non-antibiotic prophylaxis, but it is associated with significant increases in antibiotic resistance, data show.

Growing antibiotic resistance has investigators testing novel non-antibiotic prophylaxis approaches for recurrent UTIs. One promising approach involves the use of capsules of Lactobacillus rhamnosus Gr-1 and Lactobacillus reuteri RC-14.

Researchers in The Netherlands conducted a double-blind, randomized trial with 252 postmenopausal women with recurrent UTIs. The mean age of the subjects was 64 years (range 43-86 years). All subjects received either once daily 480 mg of trimethoprim-sulfamethoxazole (TMP/SMX) or twice daily oral capsules of L. rhamnosus GR-1 and L. reuteri RC-14 for one year.

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The primary end points were the cumulative number of symptomatic UTIs at 12 months as well as time to the first UTI and development of antibiotic resistance in Escherichia coli. Investigators reported findings here at the 2009 Interscience Conference on Antimicrobial Agents and Chemotherapy.

The mean number of reported symptomatic UTIs in the year before the study began was 7 in the women in the TMP/SMX group and 6.8 in the lactobacillus group. After receiving 12 months of prophylaxis, the mean number of UTIs dropped significantly to 2.8 in the TMP/SMX group and 3.1 in the lactobacillus group.

The median time to a first symptomatic UTI was six months for the TMP/SMX group compared with three months for the lactobacilli group. Although antibiotic treatment was slightly more effective, it led to an increase in antibiotic resistance. After just four weeks of TMP/SMX prophylaxis, bacterial resistance to TMP/SMX, trimethoprim, and amoxicillin increased from about 20%-40% to approximately 80%-95%. Conversely, as expected, antibiotic resistance did not increase in the lactobacilli group.

“In the antibiotic group, there was a lot of antibiotic resistance,” said study coordinator Mariëlle Beerepoot, MD, who is an attending physician at the Academic Medical Center, Amsterdam, Netherlands. “So while there was a little difference in the clinical efficiency in favor of the antibiotic group, it came at the expense of the emergence of antibiotic resistance. So one could argue that it might be that lactobacilli are preferred because there is less development of antibiotic resistance.”

Clinicians need to carefully weigh both the risks and benefits that accompany TMP/SMX prophylaxis in post-menopausal women, Dr. Beerepoot added.

“There is always a need for more research to confirm our findings,” Dr. Beerepoot told Renal & Urology News. “As far as we know this is the first trial comparing lactobacilli with antibiotic prophylaxis. The emergence of antibiotic resistance is extremely important and we need to find non-antibiotic forms of prophylaxis to minimize antibiotic resistance. Our study is hopefully a first step toward finding new non-antibiotic forms of prophylaxis.”