Rifaximin Delayed Release for the Prevention of Recurrent Acute Diverticulitis and Diverticular Complications.

Key Inclusion Criteria: * Men and women aged 18-80 years at screening. * Female participants must be either of non-childbearing potential or of childbearing potential with a negative pregnancy test result at screening and randomization AND agreeing to use a highly effective method of contraception. * A previous documented episode of diverticulitis between 30 and 180 days prior to screening. * Clinical remission from acute diverticulitis at screening Key Exclusion Criteria: * History of two or more acute diverticulitis episodes or history of any diverticular complication. * Any documented current organic disease of the gastrointestinal tract other than diverticulosis * Laboratory signs of clinically significant acute inflammation or signs/symptoms of diverticular complications. * Diagnosis or history of inflammatory bowel disease (or other conditions associated with ulcerative lesions of the intestinal tract). * Patients with positive Clostridium difficile toxin stool assay. * Use of marketed rifaximin (or neomycin or other low-absorbable oral antibiotics) during or after the previous episode of acute diverticulitis. * Severe hepatic impairment * Severe kidney impairment * Any other current significant health condition that in the Investigator's judgement may: i) jeopardize the patient's safe participation in the trial or ii) make unlikely the patient's completion of the study or iii) make unlikely the patient's compliance with the study procedures. * History of hypersensitivity to rifaximin, rifamycin-derivatives or any of the rifaximin delayed release or placebo excipients. NOTE: Other protocol defined Inclusion/Exclusion criteria apply