Probiotic May Help Prevent Recurrent Urinary Tract Infection

Megan Brooks

April 20, 2011

April 20, 2011 — In a randomized, double-blind phase 2 study, an intravaginal probiotic composed of Lactobacillus crispatus CTV-05 (Lactin-V, Osel Inc) reduced the rate of recurrent urinary tract infection (rUTI) in UTI-prone women by roughly one half, which compares favorably with historical data on antimicrobial prophylaxis, the researchers say.

They add that larger trials are warranted to see whether use of vaginal Lactobacillus could replace long-term antimicrobial preventive treatments in women susceptible to rUTI.

The study was published online April 15 and in the May 15 print issue of Clinical Infectious Diseases.

UTIs are common in women and frequently recur, Ann Stapleton, MD, from the University of Washington in Seattle, and colleagues note in their report. It has been shown, they add, that women with rUTIs often have alterations in vaginal microbiota, including depletion of lactobacilli.

A phase 1 study of Lactobacillus crispatus CTV-05 showed that the probiotic can be given as a vaginal suppository with minimal adverse effects to healthy women with a history of rUTI. In the phase 2 study, 100 premenopausal women (median age, 21 years) with a history of rUTI received antimicrobials for acute UTI and then were randomly assigned to receive either Lactobacillus crispatus CTV-05 or placebo vaginal suppository gelatin capsules administered once daily for 5 days, followed by once weekly for 10 weeks.

"We found that Lactin-V reduced the risk of rUTI approximately as effectively as antimicrobial prophylaxis, achieved high-level vaginal colonization in most women, and was well tolerated," Dr. Stapleton and colleagues report.

According to the investigators, culture-confirmed rUTI occurred in 7 (15%) of 48 of women who received Lactobacillus crispatus CTV-05 compared with 13 (27%) of 48 women who received placebo (relative risk [RR], .5; 95% confidence interval [CI], .2 - 1.2).

A high level of vaginal colonization with L crispatus throughout follow-up was associated with a significant reduction in rUTI only among women receiving Lactobacillus crispatus CTV-05 (RR for Lactin-V, .07; RR for placebo, 1.1; P < .01).

The safety profile of the probiotic mirrored that seen in the phase 1 study. Adverse effects were reported by 56% of women receiving Lactobacillus crispatus CTV-05 and 50% of those receiving placebo. The most common adverse effects included vaginal discharge or itching or moderate abdominal discomfort.

A novel aspect of this study, the authors say, is the application of quantitative polymerase chain reaction to assess vaginal microbiota after UTI. This enabled them to define sentinel changes in vaginal microbiota with or without the Lactobacillus crispatus CTV-05 probiotic.

Using quantitative polymerase chain reaction to assess L crispatus colonization in women in both study groups, the researchers say, allowed them to distinguish the natural recovery of the vaginal microbiota after UTI, as may have potentially occurred in the placebo group, from specific effects attributable to the probiotic.

What was "striking," the investigators add, was that placebo-treated women often had high concentrations of vaginal L crispatus during follow-up, yet this failed to protect them from rUTI (RR, 1.1; 95% CI, .4 - 3.1). In contrast, women who received Lactobacillus crispatus CTV-05 and achieved high colonization were protected from rUTI (RR, .07; 95% CI, .02 - .3; P < .01).

"Lactin-V after treatment for acute UTI," they conclude, "confers a significant advantage over repopulation of the vaginal microbiota with endogenous L. crispatus."

"Ongoing studies in our group are directed at understanding the mechanisms of protection in vivo and optimizing this prophylactic regimen," they note.

The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases and the Office of Research in Women's Health at the National Institutes of Health. Results of the trial also were presented at the 48th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy/46th Annual Meeting of the Infectious Diseases Society of America, Washington, DC, and the 47th Annual Meeting of the Infectious Diseases Society of America, Philadelphia, Pennsylvania. The authors have disclosed no relevant financial relationships.

Clin Infect Dis. 2011;52:1212-1217. Full text

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