The investigators are trying to determine if oral Probiotics(Umeta-mimi,30 days) with Metronidazole vaginal suppositories (7 days) is better than using Metronidazole vaginal suppositories(7 days) only in preventing the recurrence of bacterial vaginosis

Studies have shown that oral Probiotics(Umeta-mimi) can significantly promote the recovery of vaginal flora mainly because intestinal microbiota can migrate and affect vaginal microecology. This project aims to evaluate the efficacy of oral Probiotics(Umeta-mimi,30 days) with Metronidazole vaginal suppositories(7 days) in the treatment of bacterial vaginosis (BV) and to explore the correlation between vaginal flora and fecal flora by detecting the metagenomics of vaginal secretions and intestinal feces at the time of baseline phase,14 days after treatment， the first month after treatment, 5-7 days after third menstruation after treatment and 5-7 days after sixth menstruation after treatment

Inclusion Criteria:

1. Aged 18 to 55 years old, with history of sexual activity,
2. Amsel criterion for diagnosing BV
3. Sign informed consent

Exclusion Criteria:

1. History of systemic organic diseases or psychiatric diseases
2. Planning for or during pregnancy, lactation, menstruation
3. within 5 days of onset of the disease, any antibiotics has been used
4. Long-term use of contraceptives or immunosuppressant
5. Anaphylactic constitution or allergic to known ingredients of research drugs
6. No same fixed partner (RSP) before and after treatment