Patients will receive open-label rifaximin 550mg tid x 4 weeks.

Rifaximin 550mg

Remission, which will be define as less than 3 stools per day and less than 1 watery stool per day within the prior 7 days as per Hjortswang criteria, which has been used as the standard definition of remission in most all randomized clinical trials evaluating budesonide and MC. Investigators will also look at number of bowel movements, abdominal pain, incontinence, and nocturnal bowel movements. Symptoms will be compared at Week 0 and Week 6.

Our institution has identified histologic parameters associated with more severe disease activity. In collaboration with pathologists, investigators will compare histologic inflammation on patients before and after treatment. Histology will be assessed via standard H&E staining, specifically looking at surface epithelial changes associated with disease severity.

The MCDAI scale was developed to best predict a patient's quality of life as well as approximate a physician's global assessment. In multivariate analysis, the MCDAI demonstrated four independent clinical features associated with the physician global assessment including the number of unformed stools daily, number of nocturnal stools, abdominal pain, and number of episodes of fecal incontinence. These factors were used to develop estimated regression coefficients as weights produced the MCDAI formula: 1.1+0.31 (average number of unformed stools daily over the past week; continuous variable)+0.78 (nocturnal stools over past week, 0=absent, 1=present)+0.22 (maximum abdominal pain over past week, score 1-10)+0.11 (average weight loss per month (lbs))+0.93 (fecal urgency over past week, 0=absent, 1=present)+0.01 (number of episodes of fecal incontinence over past month; continuous variable).

This will be assessed at Week 0 and at Week 6.