The primary objective of this trial was to assess the safety and efficacy of rifaximin 550

selleck chemicals mg compared with placebo in the prevention of TD during late summer, fall, and winter months in Mexico. University of Texas physicians participated in the formal student orientations held on campuses in three Spanish schools in Cuernavaca, Mexico, and one Spanish school in Guadalajara, Mexico, from July 25, 2009 to January 16, 2010. Students were provided with health hints on staying well in Mexico, including describing the problems of accidents, altitude, constipation, and diarrhea, and offering strategies to prevention of TD. The prophylaxis clinical trial was then described. Eligible participants were ≥18 years of age traveling to Mexico for academic studies. In the week before traveling to Mexico, they could not have experienced Selleck Olaparib diarrhea or received an antibacterial drug with expected activity against prevalent enteric pathogens (ie, fluoroquinolones, macrolides, azalides, or trimethoprim-sulfamethoxazole). Treatments were randomly assigned 1 : 1 to receive one rifaximin 550 mg tablet (Xifaxan Tablets, Salix Pharmaceuticals, Inc, Morrisville, NC, USA) or one placebo tablet (identical in appearance to rifaximin tablet) administered orally once daily at the morning. The subjects were provided with their study medication at enrollment and were treated

for 14 days on a double-blind ID-8 basis. Each group was followed for a third week off medication as part of the study. TD was defined as three or more unformed stools during a 24-hour period plus at least one of the following abdominal symptoms: nausea, vomiting,

fecal urgency, or tenesmus. Mild diarrhea (MD) was defined as one or two unformed stools during a 24-hour period plus at least one of the described abdominal symptoms for TD. When a subject experienced TD, he or she was instructed to have a stool sample collected and submitted to our local laboratories, where it was shipped by overnight courier to Houston for determination of bacterial pathogens by previously described culture methods11 and presence of parasites in stool by enzyme immunoassay using commercially prepared kits for Giardia, Entamoeba, and Cryptosporidium (Alexon, Sunnyvale, CA, USA). The study was approved by the committee for the protection of human subjects of the University of Texas Health Science Center at Houston. All participants provided written informed consent. The sample size selected (50 in each group) was based on comparable sample sizes in previous prophylactic studies that have been conducted9,10 and by a calculation of 95% power, 0.05 significance level, 80% protection rate for prophylaxis, and a 40% attack rate for the placebo with a 10% dropout rate. The primary end point was reduction in occurrence of diarrhea during each of the 2 weeks of study.