Despite these challenges, local estrogen replacement is generally well-tolerated and, with infrequent dosing (twice weekly), has few contraindications. In fact, local estrogen replacement is one of the most highly effective regimens for UTI prevention among postmenopausal women, who can otherwise be difficult to treat for recurrent UTIs.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Vaginal estrogen is an effective therapy for the prevention of UTIs in postmenopausal women.
Cranberry supplementation may prevent UTIs,
but products vary widely
Stothers L. A randomized trial to evaluate effectiveness and cost-effectiveness of naturopathic cranberry products as prophylaxis against urinary tract infection in women. Can J Urol. 2002;9(3):1558–1562.
Cranberries have been used for many years in various formulations to prevent UTI, but no definitive mechanism has been established. In theory, cranberries keep bacteria from adhering to the urothelium.10 In vitro studies have revealed that Escherichia coli is prevented from adhering to uroepithelial cells by two components of cranberry—fructose and proanthocyanidins.10
In this trial of 150 sexually active women (ages 21–72 years) who had experienced at least two UTIs in the past calendar year, Stothers randomly assigned participants to one of three arms for 12 months:
- placebo tablets and cranberry juice (n = 50)
- cranberry tablets and placebo juice (n = 50)
- placebo tablets and placebo juice (n = 50).
Tablets were taken twice daily, and juice was consumed three times daily. All cranberry juice was organic, unsweetened, and unfiltered and taken in 250-mL servings; cranberry tablets were 1:30 parts concentrated cranberry juice.
The risk of UTI during treatment was reduced significantly in the groups taking a cranberry formulation, compared with placebo. Twenty percent of patients consuming cranberry juice experienced a UTI during treatment, compared with 18% of those taking a cranberry tablet and 32% of those in the placebo group (P<.05). In this study, the annual cost of prophylaxis with cranberry juice was $1,400 per woman, and it was $624 per woman for the cranberry tablets. Compliance was lowest among women consuming cranberry juice, decreasing at times to less than 80%.
Findings are difficult to extrapolate
This randomized, double-blind study demonstrated a significant reduction in the rate of UTI with cranberry supplementation, compared with placebo, among women with a mean age of 40 to 44 years. However, because cranberry preparations, juice, and tablets are not regulated as to the amount and bioavailability of the active ingredient, it is difficult to compare one to another and extrapolate to a particular type of preparation.
This study does highlight the higher rate of noncompliance and cost with cranberry juice, although it was as effective at reducing UTIs as cranberry tablets.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Cranberry supplementation reduced the risk of UTIs in sexually active women; placebo did not. Cranberry use may be an alternative to postcoital antibiotic prophylaxis; a randomized comparison of these therapies is needed.
Can nonhormonal therapy alter vaginal flora?
Stapleton AE, Au-Yeung M, Hooton TM, et al. Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection. Clin Infect Dis. 2011;52(10):1212–1217.
Probiotics have been used recently in attempts to prevent recurrent UTI, albeit with very little evidence in the literature. Their effectiveness is plausible due to promotion of healthy vaginal flora.
This study by Stapleton and colleagues enrolled premenopausal women (ages 18–40) with a history of one UTI within the past calendar year and a current, active, uncomplicated UTI. Ninety-nine percent of participants were sexually active. All women were treated with a standard antibiotic regimen for UTI. Seven to 10 days later, participants were randomly assigned to:
- Lactobacillus crispatus vaginal suppository [Lactin-V (Osel)], daily for 5 days and then weekly for 10 weeks (n = 50), or
- placebo (same regimen) (n = 50).
The risk of UTI was 15% among women in the probiotic group, compared with 27% in the placebo group—but this difference was only statistically significant for women who had a higher level of Lactobacillus crispatus vaginal colonization in the treatment group.
Vaginal probiotic formulations may be hard to obtain
The use of probiotics to prevent recurrent UTIs is new and innovative. However, vaginal probiotic formulations are not widely available, and most commercially available oral probiotic formulations are marketed for digestive health—an area where the effects have been studied widely.
In this study, the mean age was 21 years. Given that hypoestrogenization is associated with decreased vaginal colonization with Lactobacillus, an interesting area of future study would be the use of probiotics in postmenopausal women.
Continued investigation of probiotics is warranted, as this approach could help in the treatment of women who have intolerance to antibiotics and is generally considered safe and well-tolerated.