Eligibility Criteria:
* INCLUSION CRITERIA:
Females 18-40 years of age must meet the following criteria to be eligible for participation in this study:
* Willing and able to comply with the procedures of the protocol
* Able to provide informed consent
* Able to swallow capsules
* Have a history of regular (approximately 21-35 day) menstrual cycles prior to initiation of hormonal contraception
* On oral contraceptives for at least 3 months prior to sampling (see Participation of Women below)
Participation of Women:
Contraception:
Because menstruation is known to affect the vaginal microbiome and because oral contraceptives produce predictable menstrual cycles, subjects must be on oral contraceptives in order to be eligible for the study. Additionally, since amoxicillin may theoretically reduce the efficacy of oral contraceptives, subjects must agree to use an additional form of contraception (barrier method, abstinence) while receiving the study drug.
EXCLUSION CRITERIA:
A subject will not be eligible if she has any of the following:
* Pregnancy
* Breastfeeding
* Known allergy to beta-lactam antibiotics (e.g., penicillin)
* Body mass index (BMI) greater than or equal to 35 or less than or equal to 18 at screening visit
* Vital signs outside of acceptable range at screening visit (i.e. blood pressure \> 160/100, oral temperature \> 100 degrees F, pulse \> 100)
* Primary or acquired immunodeficiency, including Human Immunodeficiency Virus (HIV) (diagnosed via an FDA-approved test)
* Hepatitis C seropositivity or positive Hepatitis B surface antigen
* Chronic, clinically significant (requiring on-going medical management or medication) pulmonary, cardiovascular, dermatologic, endocrine, gastrointestinal, hepatic or renal functional abnormality, as determined by medical history and physical examination and/or laboratory testing (Complete blood count \[CBC\] with differential, Acute Care Panel, Hepatic Panel)
* Active malignancy or history of malignancy for which there is not reasonable assurance of sustained cure
* Major surgery of the gastrointestinal tract, including any major bowel resection at any time, with the exception of cholecystectomy and appendectomy, in the past five years
* Genitourinary/Gynecologic conditions, including:
1. Urinary incontinence necessitating use of incontinence protection garments
2. Treatment for or suspicion of ever having had toxic shock syndrome
3. History of hysterectomy
4. History of vulvar, vaginal or cervical dysplasia within the previous 5 years
5. History of condyloma or human papillomavirus (HPV) diagnosed within the previous 2 years
6. History of candidiasis, urinary tract infection, or STD (specifically chlamydia, gonorrhea, syphilis, genital herpes, trichomoniasis) diagnosed within the previous 6 months
7. Evidence (by history or physical exam) of vulvar or vaginal irritation at screening
* Chronic smokers and subjects who use smokeless tobacco products (due to known effects of tobacco on the oral microbiome)
* Exposures to the following agents (which could affect the microbiome) within 6 months prior to sampling:
1. Systemic antibiotics, antifungals, antivirals or antiparasitics (intravenous (IV), intramuscular (IM) or oral)
2. Vulvar/vaginal antifungal or hormonal medications
3. Intrauterine device (IUD) or hormonal vaginal ring (e.g. Nuvaring) due to unknown duration of local hormone effects
4. Oral, IV, IM, nasal or inhaled corticosteroids, or use of high-dose topical steroids in areas to be sampled
5. Immunosuppressive or immune-modulating agents, such as cytokines, methotrexate or other chemotherapies
6. Large doses of commercial probiotics (greater than or equal to 10(8) cfu/day) (ordinary fermented beverages/milks/yogurts/foods are acceptable)
7. Intranasal influenza vaccination due to effects on mucosal immunity
* Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer s ability to give informed consent
* Creatinine clearance \< 50 mL / min