Rifaximin, gut microbes and mucosal inflammation: unraveling a complex relationship

Gut Microbes. 2014 Jul 1;5(4):571-5. doi: 10.4161/gmic.32130.


Rifaximin is a non-systemic, broad-spectrum antibiotic that acts against gram-positive, gram-negative, and anaerobic bacteria. Clinical studies indicate that rifaximin is beneficial in treating irritable bowel syndrome (IBS). The mechanism responsible for the beneficial effects of rifaximin is not clear. In a recent study, we reported that rifaximin alters the bacterial population in the ileum of rats, leading to a relative abundance of Lactobacillus species. These changes prevent gut inflammation and visceral hyperalgesia caused by chronic stress. To more closely mirror human clinical studies in which rifaximin is used to treat IBS symptoms, we performed additional studies and showed that rifaximin reversed mucosal inflammation and barrier dysfunction evoked by chronic stress. These beneficial effects were accompanied by a striking increase in the abundance of Lactobacillaceae and a marked reduction in the number of segmented filamentous bacteria after rifaximin treatment. These microbial changes may contribute to the antiinflammatory effects of rifaximin on the intestinal mucosa.

Keywords: Lactobacillus; gut microbiota; inflammatory cytokines; irritable bowel syndrome; psychological stress; segmented filamentous bacteria; tight junction protein.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Anti-Bacterial Agents / administration & dosage*
  • Anti-Inflammatory Agents / administration & dosage*
  • Bacteria / drug effects*
  • Bacteria / immunology
  • Biota / drug effects*
  • Disease Models, Animal
  • Gastrointestinal Tract / microbiology*
  • Immunologic Factors / administration & dosage
  • Inflammation / pathology
  • Inflammatory Bowel Diseases / drug therapy*
  • Intestinal Mucosa / pathology
  • Rats, Wistar
  • Rifamycins / administration & dosage*
  • Rifaximin
  • Treatment Outcome


  • Anti-Bacterial Agents
  • Anti-Inflammatory Agents
  • Immunologic Factors
  • Rifamycins
  • Rifaximin