Use of Lactobacillus probiotics for bacterial genitourinary infections in women: A review

Background: Lactobacilli are the dominant bacteria of the vaginal flora and possess antimicrobial properties that regulate other urogenital microbiota. Incomplete cure and recurrence of genitourinary infections lead to a shift in the local flora from a predominance of lactobacilli to coliform uropathogens. Use of Lactobacillus-containing probiotics to restore commensal vaginal flora has been proposed for the treatment and prophylaxis of bacterial urogenital infections. Objective: This review summarizes randomized controlled trials that have assessed the therapeutic efficacy and tolerability of lactobacilli in bacterial vaginosis (BV) and urinary tract infection (UTI). Methods: Relevant randomized controlled trials published in English were identified through a search of MEDLINE (through November 2007), ClinicalTrials.gov, and the Cochrane Database (second quarter 2007). The search terms included probiotics, Lactobacillus, lactobacilli, urinary, urogenic, bacterial vaginosis, vaginal, colonization, bacteremia, sepsis, pathogenic, taxonomy, diagnosis, and infections. Results: Eleven randomized controlled trials were identified that investigated the effects of lactobacilli in the treatment and prophylaxis of bacterial urogenital infections. In the 2 studies that reported a beneficial effect for probiotics in the treatment of BV, cure rates for lactobacilli at 30 days were 60% (P = 0.004) and 88% (P < 0.005), more than double the effect of controls. One trial reported a 35% reduction in recurrent episodes of BV compared with placebo (P = 0.004). Among the 4 trials involving treatment of UTI, 1 reported a 73% reduction in episodes of recurrent UTI compared with the previous year (P = 0.001). Seven studies found no therapeutic effect of lactobacilli in the treatment or prophylaxis of BV or UTI. Only 2 of the identified trials attempted to validate the probiotic dosing strategy by obtaining quantitative evidence of local colonization with lactobacilli and had sufficient power to detect treatment effects, and only 1 trial addressed the stability of the probiotic product at the end of the study. Conclusions: Despite enhanced cure rates in some studies, concerns about product stability and limited documentation of strain-specific effects prevent recommendations for the use of Lactobacillus-containing probiotics in the treatment of BV. The results of studies of lactobacilli for the prophylaxis of UTI remain inconclusive as a result of small sample sizes and use of unvalidated dosing strategies.