Cranberry-UTI Study Finds Antibiotic More Effective; Antibiotic Increased Drug Resistance

A yearlong study on 221 premenopausal women suffering from recurrent urinary tract infections (UTIs) has concluded that UTI recurrences were better avoided with an antibiotic than a cranberry dietary supplement. But the antibiotic promoted antibiotic resistance.

Antibiotic treatment of UTI will help kill bacteria. Cranberry supplementation is known to provide an anti-adhesion effect, causing bacteria to slip beyond the bladder rather than attach to it.

Published in the July issue of Archives of Internal Medicine, the study followed 221 women taking either 480 mg daily of the antibiotic drug trimethoprim-sulfamethoxazole (TMP-SMX) or 500 mg twice daily of Cran-Max cranberry extract supplied by Proprietary Nutritionals Inc. (Kearny, NJ).

After 12 months, the researchers identified the following key results of supplementation:

• Mean UTI recurrence was 1.8 with antibiotic treatment and 8 with cranberry supplementation.

• Mean time to first recurrence was 8 months with antibiotic treatment and 4 months with cranberry supplementation.

• Antibiotic group experienced increased resistance to antibiotic Cipro from 8.3% at baseline to 23.1% at 12 months, and 86.3% of E. coli isolates became resistant to TMP-SMX after one month.

While the study’s researchers note an increased resistance to UTI recurrence with the antibiotic, a weakness was pointed out regarding the level of type A procyanidins (PACs), which are understood as providing cranberry’s anti-adhesion activity:

The results of a recently published in vitro study suggest that the administration of PAC, 72 mg/d…may offer some protection against bacterial adhesion in the urinary tract until 24 hours after cranberry consumption. This was not known during the start of the present study, and in our batch only 9.1 mg of PAC per gram of cranberry extract was measured. The daily dose of type A PACs that was used in our study is equivalent to a daily dose of 75 mL of Ocean Spray cranberry juice (27% cranberry).

This study on cranberry supplements and UTIs was funded by a grant from the Netherlands Organization for Health Research and Development.