Response to Antibiotic Treatment of Bacterial Vaginosis Predicts the Effectiveness of LACTIN-V (Lactobacillus crispatus CTV-05) in the Prevention of Recurrent Disease

Abstract

Objectives Live biotherapeutic products (LBPs) containing vaginal Lactobacillus crispatus are promising adjuvant treatments to prevent recurrent bacterial vaginosis (BV) but may depend on the success of initial antibiotic treatment. Methods A post hoc analysis of data collected during the phase 2b LACTIN-V randomized control trial (L. crispatus CTV-05) explored the impact of clinical BV cure defined as Amsel criteria 0 of 3 (excluding pH, per 2019 Food and Drug Administration guidance) 2 days after completion of treatment with vaginal metronidazole gel on the effectiveness of an 11-week LACTIN-V dosing regimen to prevent BV recurrence by 12 and 24 weeks. Results At enrollment, 88% of participants had achieved postantibiotic clinical BV cure. The effect of LACTIN-V on BV recurrence compared with placebo differed by initial clinical BV cure status. The LACTIN-V to placebo risk ratio of BV recurrence by 12 weeks was 0.56 (95% confidence interval, 0.35–0.77) among participants with initial clinical BV cure after metronidazole treatment and 1.34 (95% confidence interval, 0.47–2.23) among participants without postantibiotic clinical BV cure. Among women receiving LACTIN-V, those who had achieved postantibiotic clinical BV cure at enrollment reached higher levels of detectable L. crispatus CTV-05 compared with women failing to achieve postantibiotic clinical BV cure. Conclusions LACTIN-V seems to only decrease BV recurrence in women with clinical cure of BV after initial antibiotic treatment. Future trials of LBPs should consider limiting enrollment to these women.