Cranberries can't match trimethoprim-sulfamethoxazole in preventing UTIs

Trimethoprim-sulfamethoxazole (TMP-SMX) 480 mg once daily is more effective than cranberry capsules 500 mg twice daily for the prevention of recurrent urinary tract infections (UTIs) in premenopausal women-but it exacerbates the problem of emerging antibiotic resistance.

Researchers from the Netherlands conducted a double-blind, noninferiority trial involving 221 women with recurrent UTIs. They randomized the women to receive 12 months of prophylaxis with either TMP-SMX or the cranberry capsules. After 1 year, the mean number of women who had at least 1 symptomatic UTI was higher in the cranberry group than in the TMP-SMX group (4.0 vs 1.8; P=.02). Additionally, the proportion of women with at least 1 symptomatic UTI was higher in the cranberry group than in the TMP-SMX group (78.2% vs 71.1%). Median time to first symptomatic infection was half in the cranberry group of what it was in the antibiotic group (4 months vs 8 months).

However, after 1 month of treatment, although only about one-quarter of fecal (23.7%) and asymptomatic bacteriuria Escherichia coli isolates (28.1%) in the cranberry group were TMP-SMX resistant, 86.3% of fecal and 90.5% of asymptomatic bacteriuria E coli isolates in the antibiotic group were resistant to TMP-SMX. After 1 month, the isolates in the latter group also showed increased resistance rates to trimethoprim, amoxicillin, and ciprofloxacin. Resistance rates returned to baseline 3 months after discontinuation of TMP-SMX.

Beerepoot MA, Ter Riet G, Nys S, et al. Cranberries vs antibiotics to prevent urinary tract infections: a randomized double-blind noninferiority trial in premenopausal women. Arch Intern Med. 2011;171(14):1270-1278.