Probiotics may increase cure rates for bacterial vaginosis

In women with bacterial vaginosis (BV), probiotics reduce the levels of interleukin 1 beta (IL-1β) and interleukin 6 (IL-6), and lower the overall Nugent score and Amsel’s criteria for restitution of a balanced vaginal microbiota, according to a systematic review in the Internal Journal of Clinical Practice.

Probiotics can also reduce the vaginal colonization of Group B streptococci among pregnant women.

“Pre/probiotic regimens, when used for BV treatment, are usually safe and can exhibit long-term and short-term benefits,” wrote the authors.

The review searched Medline, Scopus, Embase and Google Scholar for randomized controlled trials published in English from 2010 to 2020 to determine the efficacy of pre/probiotics on the treatment of BV in pregnant and nonpregnant women. There were 24 eligible clinical trials, representing 8,242 women participants.¹

Of the 24 studies, 10 examined the effect of probiotics in combination with antibiotics, 12 assessed the effect of probiotics and 2 evaluated the effect of prebiotics without antibiotics on the BV treatment.

A total of 16 different probiotic species were given 1, 2, or 3 times daily, at doses of 1 × 104 to 6 × 109 colony forming units (CFUs). The average dose of probiotics was 1.35 × 109 CFU.

The most common probiotic administered was Lactobacillus rhamnosus (28.3%), followed by Lactobacillus reuteri (16.9%) and Lactobacillus gasseri (9.4%).

A cocktail of different probiotic species was more effective than probiotic monotherapies.

Half of the trials found that pre/probiotics combined with metronidazole are more efficient in reducing BV recurrence rate compared to metronidazole alone.

Furthermore, both the intravaginal and oral administration of pre/probiotics are linked to significant improvements in the cure rate of BV.

Although the intravaginal route appears to be the preferred route, the ideal route of delivery for pre/probiotics remains controversial, according to the authors, who noted that some studies indicate that orally applied L reuteri and L gasseri may positively influence vaginal health.

For the oral route, it is essential to consider the viability of the probiotic strains under high concentrations of gastric acid and bile salts, as well as the time the strains take to reach and colonize the vagina, which varies from person to person.

It is unclear whether the initial pathogenic event is the overgrowth of anaerobes or the primary diminution of L reuteri and L gasseri.

Overall, 14 of the 24 trials concluded that BV patients who receive probiotics alone have significantly higher cure rates than those receiving placebo.

Probiotics also improve the microbial pattern in vaginal dysbiosis by producing lactic acid and maintaining a normal vaginal pH, degrading the epithelium glycogen and inhibiting the growth of pathogens, and producing bacteriocins, biosurfactants and hydrogen peroxide (H2O2) and competing with pathogens for adhesion sites.

Some studies confirmed that certain strains of vaginal lactobacilli can create H2O2, which inhibits adherence of Gardnerella vaginalis to the epithelial cells and produces an immunomodulatory effect.

However, there were significant variations among the pre/probiotics interventions—including variation in dosage, administration routes, therapy duration, prebiotics type, and probiotics strain and species – thus making comparisons across different trials challenging.

Commercially available probiotics products can also have variations in their ingredients.

Because probiotics are not systemically absorbed, they are generally considered safe for healthy people. None of the studies reported significant adverse effects.

“In order to prove the benefits of pre/probiotics in BV treatment, additional high-quality research is required,” wrote the authors.

Reference

1. Afifirad R, Emamie AD, Zadeh RG, et al. Effects of pro/prebiotics alone over pro/prebiotics combined with conventional antibiotic therapy to treat bacterial vaginosis: a systematic review. Int J Clin Pract. Published online April 21, 2022. doi:10.1155/2022/4774783