Rifaximin, a nonabsorbed oral antibiotic, prevents shigellosis after experimental challenge.

Background: This double-blind, placebo-controlled study was conducted to assess the efficacy of the nonabsorbed oral antibiotic rifaximin to prevent shigellosis in volunteers challenged with Shigella flexneri.

Methods: Volunteers were randomized to receive either prophylactic rifaximin (200 mg 3 times daily for 3 days; n = 15) or placebo (n = 10) on days 0, 1, and 2. On day 1, volunteers were challenged with approximately 1500 colony-forming units of S.