Lactin-V for Bacterial Vaginosis

Claudia is a 23-year-old graduate student happily settling into a new relationship. She first visited the women’s health clinic 4 months ago and was treated for bacterial vaginosis with a 7-day course of oral metronidazole. Today, sitting across from you, she sheepishly reports that despite completing the treatment, the foul-smelling discharge has returned. A pelvic exam and diagnostic testing confirm recurrence of bacterial vaginosis. You explain to her that while frustrating, recurrence is common, and treatment requires another round of antibiotics. 

Bacterial vaginosis is caused by an imbalance in the vaginal microbiome due to the replacement of dominant lactobacilli with various anaerobic species. The acid-producing lactobacilli play an important role in vaginal homeostasis, which is disrupted by their replacement. Treatment typically involves antibiotic therapy, but as many as 75% of women will experience recurrence within 3 months. 

As you write your notes later that evening, you recall a recent study published in NEJM describing a different kind of treatment for recurrent bacterial vaginosis. The placebo-controlled trial examined the efficacy of vaginal Lactobacillus crispatus CTV-05 (Lactin-V), a lactobacillus replacement therapy, for the prevention of bacterial vaginosis recurrence following treatment with vaginal metronidazole. The authors found that treatment with Lactin-V significantly reduced the incidence of recurrence. Although not yet FDA approved, this therapy will help patients like Claudia in the future.

The following NEJM Journal Watch summary explains the study in more detail.

Anna Wald, MD, MPH reviewing Cohen CR et al. N Engl J Med 2020 May 14 

Vaginal dysbiosis (also known as bacterial vaginosis) is characterized by displacement of optimal vaginal microflora by diverse bacteria, often recurs after therapy, and has been associated with multiple adverse health outcomes. To assess whether intravaginal replacement of Lactobacillus crispatus, a bacterium associated with optimal vaginal health, reduces risk for recurrence, investigators performed a double-blind, placebo-controlled NIH-funded trial in 228 women who had recently received metronidazole for dysbiosis. The women used prefilled applicators to self-administer a commercial preparation of intravaginal powder (not yet FDA-approved) containing L. crispatus or placebo for 4 consecutive days during the first week, then twice weekly for 10 weeks.

At week 12, 30% of women receiving L. crispatus versus 45% of those receiving placebo had recurrent vaginal dysbiosis defined by clinical and microbiologic criteria (risk ratio, 0.66; P=0.01). At week 24, recurrence rates were 39% (L. crispatus) and 54% (placebo; RR, 0.73), although recurrence status was unknown for 19% of participants. Treatment was safe and well tolerated.

Comment: This study shows that replacing beneficial vaginal bacteria can improve clinical outcomes of treatment for vaginal dysbiosis. While the effect of this intervention was substantial, it appeared to be attenuated at 24 weeks of follow up, suggesting that continued administration may be needed to maintain normal vaginal microflora. The advantage of replacing beneficial bacteria has also been demonstrated for fecal transplants in patients with recurrent C. difficile infection, opening an era of improving health through manipulation of the microbiome.

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Krista is a 2019-2020 editorial fellow at the New England Journal of Medicine. She is from Nassau, Bahamas where she is training in general surgery at the University of the West Indies.