Antibiotics better than probiotics for UTIs

Although antibiotics are effective first-line treatment for recurrent urinary tract infections (UTIs), resistance to a range of antibiotics develops quickly.

Probiotic therapy for recurrent UTIs is less effective and less durable than antibiotics, but it does not contribute to antibiotic resistance.

Trimethoprim-sulfamethoxazole (TMP-SMX) is more effective than Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 for the treatment of recurrent urinary tract infections (UTIs) in postmenopausal women. However, lactobacilli do not contribute to the growing problem of antibiotic resistance, and so may have a place in treatment.

Published in the Archives of Internal Medicine (2012;172[9]:704-712), the findings come from a recent randomized, double-blind noninferiority trial. Researchers from the Netherlands randomized 252 postmenopausal women with recurrent UTIs to receive 12 months of prophylaxis with TMP-SMX, 480 mg, once daily, or oral capsules containing 109 colony-forming units of L rhamnosus GR-1 and L reuteri RC-14, twice daily.

They calculated that the mean number of symptomatic UTIs in the year preceding randomization was 7.0 in the TMP-SMX group and 6.8 in the lactobacilli group. After 12 months of prophylaxis, the number of symptomatic UTIs decreased to 2.9 and 3.3, respectively. On average, it took 3 months for the women in the lactobacilli group to develop their first UTI compared with 6 months in the TMP-SMX group.

Samples of the women’s urine and feces showed resistance to TMP-SMX, trimethoprim, and amoxicillin within the first month of treatment. By the end of 1 year of treatment, levels of TMP-SMX-resistant Escherichia coli in the samples of asymptomatic women rose from approximately 20%–40% to 80%–95%. However, 3 months after TMP-SMX was discontinued, resistance levels gradually decreased and returned to just above baseline. Resistance remained unchanged during and after prophylaxis with lactobacilli.

Interestingly, in women with complicated UTIs, prophylaxis with TMP-SMX appeared to be less effective than that with lactobacilli, possibly because resistance rates in this group were higher, the authors surmise.

One limitation of the study was that 80 women dropped out by the end of the year, some because of side effects: more women in the probiotic group than in the TMP-SMX group had diarrhea.

Although prophylaxis with lactobacilli did not meet the noninferiority criteria in preventing UTIs compared with TMP-SMX, the authors concluded that lactobacilli may be an acceptable alternative to antibiotics in women who dislike taking antibiotics.

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