Antibiotics better than cranberry extract to prevent recurring urinary tract infections

Prophylactic antibiotics are more effective than cranberry capsules in preventing recurrent urinary tract infections (UTIs), but they do increase antibiotic resistance, Dutch researchers concluded.

The double-blind, randomized noninferiority trial recruited 221 premenopausal women with at least three self-reported recurring UTIs in the previous year from all over the Netherlands. Women were randomized to 12-month prophylaxis with 480 mg of trimethoprim-sulfamethoxazole once daily (plus one placebo pill), or 500 mg of cranberry capsules twice daily. The amount of type A proanthocyanidins in the cranberry extract was 9.1 mg/g. Primary end points were the mean number of symptomatic UTIs, the proportion of patients with at least one symptomatic UTI, the median time to the first UTI, and development of antibiotic resistance of Escherichia coli.

The women were asked to collect urine and feces samples monthly from the start of the study to three months after the final prophylactic dose, and to complete a questionnaire about UTI symptoms, adverse events, infections other than UTIs, and other antibiotic use. Results appeared in the July 25 Archives of Internal Medicine.

Antibiotics worked better, with a mean of four clinical recurrences in the cranberry group compared to 1.8 in the antibiotic group (P=0.02) in the 12 months of follow-up. While 78.2% of patients in the cranberry group reported at least one symptomatic UTI, 71.1% did so in the antibiotic group. Median time to the first symptomatic UTI was four months for the cranberry extract and eight months for the antibiotic group.

However, after one month, in the cranberry group, 23.7% of fecal and 28.1% of asymptomatic bacteriuria E. coli isolates were resistant to trimethoprim-sulfamethoxazole, whereas in the antibiotic group, 86.3% of fecal and 90.5% of isolates were resistant. There were also increased resistance rates for trimethoprim, amoxicillin, and ciprofloxacin in E. coli after one month in the antibiotic group. After the antibiotic was stopped, resistance returned to baseline levels after three months. The authors concluded that that the potential benefit of antibiotics should be weighed against the greater development of antibiotic resistance.