Potential vaginal probiotics: safety, tolerability and preliminary effectiveness

Vaginal discharge is one of the common reasons for gynaecologist consultation, as bacterial vaginosis and candidiasis are the main causes of discharge. These patients frequently experience numerous problems due to recurrent infections, side effects and drug resistance therefore alternative drugs are needed. Our primary aim was to evaluate safety and tolerability of the potentially probiotic Lactobacillus crispatus strains in volunteer women considering themselves healthy. We also monitored the effects of these strains on vaginal health parameters and lactobacilli counts in vagina and intestine. Forty women were recruited into trial. Absence of chronic diseases was confirmed by questionnaire and blood analysis at screening visit. In randomised double-blind placebo-controlled crossover study the eligible participants were randomly allocated to one of four groups and had to consume one of the two study products (Pro I or Pro II) - a capsule containing 3 strains, 10⁹ cfu per strain, or placebo for 1 week. Treatment period was followed by 2-week washout period and continued with second treatment and washout period. Individuals receiving firstly probiotic, received later placebo and vice versa. Blood, vaginal and faecal samples were collected, and self-reported questionnaires were applied. Thirty subjects completed the trial. The probiotic capsules were well-tolerated. The Pro II intake resulted in a significant decrease in Nugent score (from median 3.0 to 2.0, mean 3.9 to 2.6, P=0.002) and reduction in Gardnerella vaginalis counts (log₁₀ 3.57 to 2.38; P=0.027). Reduction of total vaginal bacterial counts was revealed in Pro I group (log₁₀ 7.99 to 7.72; P=0.048). In conclusion, the selected vaginal L. crispatus strains are well tolerable and Pro II mixture is prospectively effective in reducing Nugent score and vaginal counts of G. vaginalis. Therefore, these strains seem to be promising candidates for development of novel evidence-based well-focused probiotics to target female urogenital tract disorders.