MOTIF@FRESH: Modifying Organisms Transvaginally in Females @ FRESH

Inclusion Criteria: * Premenopausal females between 18 to 25 years of age who are enrolled in the FRESH study * Nugent score ≥ 4 * Confirmation of use of effective contraceptive method by all study recipient participants (referred to as recipients) of child-bearing potential, which includes use of at least one of the following: Hormonal method, such as birth control pills, patches, injections, vaginal rings, or implants; Barrier method, such as a condom or diaphragm used with a spermicide (a foam, cream, or gel that kills sperm); Intrauterine device (IUD) - non-levonorgestrel containing * Ability and willingness to give written informed consent. Exclusion Criteria: * History of clinically significant vaginal, cervical, or uterine disease including but not limited to cancer of the female reproductive tract, prior hysterectomy, high grade cervical dysplasia (CIN III), or diagnosed with cervicovaginal infection (with the exception of bacterial vaginosis or yeast) within the 30 days prior to the procedure * Allergy to metronidazole * Use of investigational therapies or investigational vaccines within 90 days prior to study screening * Has not received the HPV vaccine and is not willing to be vaccinated * Metabolic syndrome, e.g. diabetes, pre-diabetes, glucose intolerance * Use of any immunomodulatory agents within 30 days prior to study enrollment * Participants taking any of the following medications: systemic steroids (inhaled or nasal steroid therapy is permitted), interleukins, systemic interferons, or systemic chemotherapy * History of coronary artery disease, myocardial infarction, COPD, chronic renal failure, decompensated cirrhosis, or any other condition that in the opinion of the investigator will compromise ability to participate in the study * Pap smear result of LSIL, HSIL, AGUS * Insertion of levonorgestrel-containing IUD within 90 days prior to study enrollment * Either breastfeeding, pregnant, or trying to conceive within 24 weeks prior to study enrollment; or becomes pregnant during study period * Use of probiotics and prebiotics (supplements and products, oral or vaginal) within 30 days of the study \- NOTE: Oral yogurt with live cultures and fermented foods are allowed. * Routine use of oral antibiotics i.e., daily use for acne, Hiradenitis suppurativa, or regular use for post-coital urinary tract infection prophylaxis within the past 30 days * Taken non-metronidazole antibiotics in last 30 days * Taken metronidazole within the last 2 weeks * BMI \> 40 * Positive for any of the STIs listed below or on treatment for any of them. * Neisseria gonorrhoeae * Chlamydia trachomatis * HIV * Trichomonas vaginalis * Syphilis * Mycoplasma genitalium * Currently employed at, or professionally affiliated with the FRESH clinical research site, UKZN's HIV Pathogenesis Program (HPP), or the Ragon Institute of Mass General Brigham, MIT and Harvard (referred to as "the Ragon/MGH" in this document). * Screens positive for TB by symptomatic questionnaire