Probiotic May Help Prevent Recurrent Urinary Tract
Infection
Megan Brooks
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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