Response to antibiotic treatment of bacterial vaginosis predicts the effectiveness of LACTIN-V (Lactobacillus crispatus CTV-05) in the prevention of recurrent disease

ObjectivesLive 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. MethodsA 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 FDA guidance) two 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. ResultsAt enrollment, 88% of participants had achieved clinical BV cure. The effect of LACTIN-V on BV recurrence compared to placebo differed by initial clinical BV cure status (p=0.02 by 12 weeks, and p=0.08 by 24 weeks). The LACTIN-V to placebo risk ratio of BV recurrence by 12 weeks was 0.56 (CI: 0.35, 0.77) among participants with initial clinical BV cure, and 1.34 (CI: 0.47, 2.23) among participants without clinical BV cure. Among women receiving LACTIN-V, those who had achieved clinical BV cure at enrollment reached higher levels of detectable L. crispatus CTV-05 compared to women failing to achieve clinical BV cure. ConclusionLACTIN-V appears to only decrease BV recurrence in women with clinical cure of BV following antibiotic treatment. Future trials of LBPs should consider limiting enrollment to these women.