All calculations were carried out using Stata 10.0 (College Station, TX, USA). A total of 101 subjects were enrolled into the study. Three participants dropped out from check details the study: one from the rifaximin group and two from the placebo group. Therefore, 98 subjects completed the study and were analyzed. Fifty-four participants were female (55%) and 44 (45%) were male, each treatment group had similar proportions of males and females (p = 0.2). The overall mean age at enrollment was 25 years (range, 18–67 y).

Thirty-six (37%) participants were enrolled during the summer months, while 62 (63%) during the fall and winter months. Eight (8%) participants were enrolled in Guadalajara and 90 (92%) in Cuernavaca. As noted in Table 1, 14 participants developed TD during the 2 weeks of study: 6 of 50 patients (12%) from the rifaximin group and 8 of 48 patients (17%) from the placebo group (p = 0.5). We also did not observe a difference GSI-IX purchase in the occurrence of MD between the rifaximin and placebo groups (p = 0.3) during the 3-week study period. We only saw a statistical difference during the first week of study for the development of MD

(p = 0.03). No difference in the occurrence of MD or TD between the two groups was seen during the second and third weeks of study. Twelve of 36 (33%) participants enrolled during the summer developed TD: 6 of 19 (32%) from the rifaximin group and 6 of 17 (35%) from the placebo group (p = 0.9). Meanwhile, 12 of 62 (19%) participants enrolled during the fall and winter developed TD: 5 of 31 (16%) from the rifaximin group and 7 of 31 (23%) from the placebo group (p = 0.5). No difference in the incidence of MD or TD was observed during each of the 3 weeks in participants treated during the summer months. We observed that participants taking rifaximin during the fall and winter months were also less likely to develop MD during the first week of study compared with those taking placebo during the same timeframe (2 of 30 [6.7%] vs 8 oxyclozanide of 29 [28%]; p = 0.04). Seventeen of the 25 participants (68%) suffering from TD provided a stool sample for microbiological analysis

before any antibiotic rescue therapy was administered: 10 (91%) from the rifaximin group and 7 (50%) from the placebo group. Bacterial diarrhea was detected in eight participants: six (60%) in the rifaximin group and two (29%) in the placebo group (p = 0.3; Table 1). Enteroaggregative Escherichia coli was the most common bacteria isolated (4 of 8), followed by enterotoxigenic E coli (3 of 8), diffusely adherent E coli (2 of 8), and Salmonella spp. (1 of 8). Two participants had mixed infections. No other bacterial or parasite pathogens were found. Three E coli isolates showed high minimum inhibitory concentration (MIC) for rifaximin (≥512 µg/mL): two of them isolated from participants in the rifaximin group and one taking placebo.