This research study is being done to compare the safety and efficacy of GDC-229 (test drug) against the currently marketed reference drug (metronidazole 0.75% vaginal gel) and to establish that these two drugs work better than placebo in subjects with BV.

Inclusion Criteria:

1. Non-pregnant female aged ≥ 18 years who is in good general health
2. Diagnosis of BV
3. Willing to refrain from using any intravaginal product (e.g., spermicide, tampon, douche, feminine deodorant spray, diaphragm, vaginal ring birth control, or condom with spermicide or insertion into the vagina of any drug or non-drug product during treatment), other than study treatment for the duration of the trial
4. Subjects of childbearing potential who have a negative urine pregnancy test at the Entry Visit (Visit 1) and agree to use an acceptable form of birth control throughout the study
5. Able to understand and willing to sign the informed consent form (ICF) and able to comply with the requirements of the protocol

Exclusion Criteria:

1. History of alcohol or substance abuse
2. Experienced a clinically significant medical event within 90 days
3. Abnormal pap or high risk human papillomavirus (HPV)
4. History or presence of clinically significant central nervous system (CNS), cardiovascular, pulmonary, hepatic, renal, hematologic, gastrointestinal, endocrine, immunologic, gynecologic, dermatologic, neurologic, oncologic, or psychiatric disease
5. Pregnant, lactating, or planning to become pregnant or breastfeed during the study period
6. Primary or secondary immunodeficiency
7. Evidence of any vulvovaginitis at screening other than BV
8. History of hypersensitivity or allergy to metronidazole, parabens, other nitroimidazole derivatives, or other ingredients of the GDC 229 (metronidazole 0.75% vaginal gel), metronidazole 0.75% vaginal gel (Oceanside Pharmaceuticals), or vehicle gel
9. Participating in another clinical trial

Non-pregnant female aged ≥ 18 years who is in good general health

21 months

Double-blind