Longitudinal Study of the Human Intestinal Microbiome

Inclusion Criteria: -Male or female, ages 18 to 45 years, inclusive. -Healthy as determined by screening medical history, medication history, and absence of acute illness such as gastrointestinal or respiratory infection. -Capable of understanding, consenting and complying with the entire study protocol. -Provide voluntary written Informed Consent. -Females of childbearing potential are required to utilize an appropriate method of contraception \[abstinence, oral contraceptives, IUD, condoms with spermicidal foam, surgical sterilization depots and injectable contraceptives, or diaphragms with spermicidal jelly or cream\] 30 days prior to the Week 12 visit. Exclusion Criteria: -Chronic diarrhea, inflammatory bowel disease, irritable bowel syndrome, or other gastrointestinal disorder, gastrointestinal surgery (except appendectomy, polypectomy, or herniorraphy), or severe chronic illness such as major organ failure, diabetes, HIV/AIDS. -Female who is pregnant or lactating; or a female subject with a positive urine pregnancy test determined at the Week 12 visit. -History of hypersensitivity to Ciprofloxacin, any member of the quinolone class of antimicrobial agents, or any compound of the product. -History of tendinitis or tendon rupture. -History of seizures other than febrile seizure as a young child. -Treatment with antibiotics within one month before the initial specimen collection. -History of clinically significant acute or chronic illness or other condition requiring chronic medication therapy (including systemic but not intranasal steroids), except for birth control pills, inhalers, anti-anxiety or anti-depression medications. -History of cardiac rhythm abnormalities or QT prolongation or a family history of cardiac rhythm abnormalities or sudden unexplained death. -History of current or past use of theophylline for asthma or tizanidine, due to known interaction with Ciprofloxacin. -History of spasticity (due to the potential for requiring tizanidine treatment), asthma, chronic bronchitis, emphysema, and other lung diseases (due to potential for requiring theophylline \[or dimethylxanthine\] treatment). -Medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months.