Bacterial vaginosis (BV) is a common infection of the lower genital tract with a vaginal microbiome dysbiosis caused by decreasing of lactobacilli. Previous studies suggested that supplementation with live Lactobacillus may benefit the recovery of BV, while the outcomes vary in people from different regions. Herein, we aim to evaluate the effectiveness of oral Chinese-origin Lactobacillus with adjuvant metronidazole (MET) on treating Chinese BV patients. In total, 67 Chinese women with BV were enrolled in this parallel controlled trial and randomly assigned to two study groups: a control group treated with MET vaginal suppositories for 7 days and a probiotic group treated with oral Lactobacillus gasseri TM13 and Lactobacillus crispatus LG55 as an adjuvant to MET for 30 days. By comparing the participants with Nugent scores ≥ 7 and < 7 on days 14, 30, and 90, we found that oral administration of probiotics did not improve BV cure rates (57.14% and 67.74% at day 14, 57.14% and 58.06% at day 30, 32.14% and 48.39% at day 90 for probiotic and control group respectively). However, the probiotics were effective in restoring vaginal health after cure by showing higher proportion of participants with Nugent scores < 4 in the probiotic group compared to the control group (87.50% and 71.43% on day 14, 93.75% and 88.89% on day 30, and 77.78% and 66.67% on day 90). The relative abundance of the probiotic strains was significantly increased in the gut microbiome of the probiotic group compared to the control group at day 14, but no significance was detected after 30 and 90 days. Also, the probiotics were not detected in vaginal microbiome, suggesting that L. gasseri TM13 and L. crispatus LG55 mainly acted through the gut. A higher abundance of Prevotellatimonensis at baseline was significantly associated with long-term cure failure of BV and greatly contributed to the enrichment of the lipid IVA synthesis pathway, which could aggravate inflammation response. To sum up, L. gasseri TM13 and L. crispatus LG55 can restore the vaginal health of patients recovering from BV, and individualized intervention mode should be developed to improve BV cure rates.

LG, YZ and HZ was employed by BGI Precision Nutrition (Shenzhen) Technology Company Limited.

NCT04771728

This research was supported by the National Natural Science Foundation of China (82171676 and 82201793), the Science and Technology Planning Project of Shenzhen Municipality (JCYJ20220530160206014 and JCYJ20190809101409603), and the Scientific Research Foundation of PEKING UNIVERSITY SHENZHEN HOSPITAL (KYQD202100X and KYQD2022111).

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Ethics committee of Peking University Shenzhen Hospital gave PUshenzhenH2020-009 approval for this work IRB of BGI gave 20162-T1 approval for this work

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The data that support the findings of this study have been deposited into the CNGB Sequence Archive of China National GeneBank DataBase with accession number CNP0003852.