Cranberries vs antibiotics to prevent urinary tract infection

Concern over the risk of resistance to antimicrobial agents has stimulated interest in cranberries to prevent recurrent urinary tract infections (UTIs).

Researchers in the Netherlands compared trimethoprim-sulfamethoxazole (TMP-SMX) (Septra, Bactrim) to cranberry capsules.

First, the details.

• 221 premenopausal women with recurrent UTIs were randomly assigned to a treatment group for 12 months.
• TMP-SMX 480 mg once daily
• Cranberry capsules 500 mg twice daily
• The average number of symptomatic UTIs over 12 months, the proportion of patients with at least 1 symptomatic UTI, the time to first urinary tract infection, and development of antibiotic resistance in indigenous Escherichia coli were recorded.
• Neither the patients nor researchers knew the treatment given — double blind.

And, the results.

• The average number of patients with at least 1 symptomatic UTI was significantly higher in the cranberry vs the TMP-SMX group (4.0 vs 1.8, respectively).
• The proportion of patients with at least 1 symptomatic UTI was higher in the cranberry vs TMP-SMX group (78% vs 71%).
• The time to the first symptomatic UTI was 4 months for the cranberry and 8 months for the TMP-SMX group.
• After 1 month, in the cranberry group, 24% of fecal and 28% of asymptomatic bacteriuria E coli isolates were TMP-SMX resistant.
• In the TMP-SMX group, 86% of fecal and 91% of asymptomatic bacteriuria E coli isolates were TMP-SMX resistant.
• There were increased resistance rates for trimethoprim, amoxicillin, and ciprofloxacin in these E coli isolates after 1 month in the TMP-SMX group.
• After discontinuation of TMP-SMX, resistance returned to baseline levels after 3 months.
• Antibiotic resistance did not increase in the cranberry group.
• Cranberries and TMP-SMX were equally well tolerated.

The bottom line?

The authors concluded, “In premenopausal women TMP-SMX, 480 mg once daily is more effective than cranberry capsules 500 mg twice daily to prevent recurrent UTIs.

However, “This was achieved at the expense of emerging antibiotic resistance.”

There’s lots of interest in cranberries to prevent UTIs. It’s important to not lump the results from different populations of patients or different formulations of cranberry. Here’s a review of what we know.

7/26/11 21:23 JR