Study to Evaluate Safety and Efficacy of Rifamycin SV MMX for the Treatment of Traveler's Diarrhea

Inclusion Criteria:

• Male and female patients 18 years of age or older.
• Female and male patients of child-bearing potential must agree to use an effective method of birth control (this method must be approved by the investigator and may include total abstinence from sexual intercourse) during the treatment and follow-up study periods; female patients of child-bearing potential must have a negative pregnancy test in the 72 hours before randomization; female patients who abstain totally from sexual intercourse are not required to take the pregnancy test.
• Recent travel (i.e., must be within 30 days of randomization) from an industrialized country.
• Experiencing signs or symptoms indicative of acute bacterial diarrhea (travelers' diarrhea), defined as at least three unformed, watery or soft, stools within the 24 hours preceding randomization and the duration of illness ≤ 72 hours before randomization, and able to provide an unformed stool sample during Screening (the latter can be the third unformed stool passed by the patient within the 24 hours preceding randomization); the bacterial cause of diarrhea will be confirmed by microbiology analysis of the stool sample.
• Experiencing one or more signs or symptoms of enteric infection (moderate to severe gas/flatulence, nausea, vomiting, abdominal cramps or pain, rectal tenesmus, or defecation urgency)
• Capable of and willing to give informed consent.

Exclusion Criteria:

• Fever (> 100.4ºF or 38ºC) or presence of signs and symptoms of systemic infection Note: antipyretic medication should not be administered in the 6 hours before this assessment.
• Known or suspected infection with non-bacterial pathogen before randomization.
• Presence of diarrhea for >72 hours duration.
• Presence of grossly bloody stool.
• Presence of moderate to severe dehydration (i.e., presence of orthostatic hypotension and/or dehydration requiring treatment with intravenous fluids).
• History of ulcerative colitis, diarrhea-predominant irritable bowel syndrome, Crohn's disease, celiac sprue (gluten-enteropathy), chronic pancreatitis, malabsorption, or any other gastrointestinal disease associated with diarrhea. Note: lactose intolerance treated with lactase supplements or a lactose-free diet are not excluded if these regimens are maintained during the study.
• Receiving more than two doses of an antidiarrheal medication (e.g., antimotility, absorbent, adsorbent, antisecretory, or probiotics) within 24 hours before randomization.
• Receiving one or more of the following antibiotics within 7 days before randomization, which are active against gram negative bacteria - trimethoprim/sulfamethoxazole, fluoroquinolone, azithromycin or rifaximin.
• Females pregnant or breast feeding or not using adequate birth control.
• Known intolerance/hypersensitivity/resistance to rifamycin or rifamycin-related antibiotics or to any excipient included in the study medications.
• Patients unable or unwilling to comply with study protocol (e.g., alcoholism, mental illness, travel schedule).
• Participation in a clinical study with another investigational drug in the 30 days prior to randomization or while participating in this study.
• Previous participation in this study.