One hundred twenty healthy Chinese women with a history or recurring bacterial vaginosis (BV) were randomly assigned to a daily vaginal probiotic capsule as prophylaxis that contained 8 billion colony forming units of Lactobacillus rhamnosus, L. acidophilus and Streptococcus thermophilus or a daily vaginal placebo capsule. Women were to insert the capsule 7 days on, 7 days off and 7 days on.
Women using the vaginal probiotic capsule had lower recurrence rates for BV (15.8%) vs. placebo (45.0%) and lower rates of Gardnerella vaginalis (3.5% vs. 18.3%) during the 2 to 11 month follow-up period. Through 2 months after the treatment, probiotics were effective in reducing discharge, lowering the vaginal pH and reducing the presence of clue cells. No effect was seen on reducing the odor within the two month follow-up period, but between the 2 and 11 months of follow-up, the incidence of vaginal discharge and malodor was 3-fold higher in the placebo group.
Bacterial vaginosis (BV) is the most common vaginal infection in reproductive aged women. This infection occurs when predominantly anaerobic bacteria such as Gardnerella vaginalis, as well as Mycoplasma hominis, Prevotella and Peptostreptococcus replace the dominant and normal Lactobacillus bacteria in the vagina.
A 15.8 % recurrence rate for BV, as was seen with the probiotic vaginal capsule, is similar to the 15% seen in a recent review of metronidazole gel, the most common antibiotic prescription for BV, through a two month period, but without any of the potential side effects of the metronidazole.
The proposed mechanism of recurrence of BV is thought not to be due to a reinfection but by relapse due to an abnormal vaginal flora and a lack of normal colonization of Lactobacillus species. It is likely that a significantly high number of colony forming units is required to have the good results seen in this study. In the case of this study, they used a probiotic dose 80 times greater than the Lactobacillus volume recommended to restore and maintain a normal urogenital flora environment. The Lactobacillus species load administered inhibits or destroys the pathogenic bacteria and blocks the adherence of Gardnerella vaginalis to the vaginal cells.
Wang Y, Reifer C, Miller L. Efficacy of vaginal probiotic capsules for recurrent bacterial vaginosis: a double-blind, randomized, placebo-controlled study. Amer J Obst/Gyn 2010:120.1-120.6