Cranberries can't match trimethoprim-sulfamethoxazole in preventing UTIs

September 1, 2011

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

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.