What gastrointestinal (GI) pathogens does Rifaximin cover?

From the Guidelines

Rifaximin is effective against a wide range of gastrointestinal pathogens, primarily covering gram-positive and gram-negative aerobic and anaerobic bacteria, including Escherichia coli, Salmonella species, Shigella species, and Clostridioides difficile, but it is less effective against Campylobacter jejuni and has limited activity against protozoa and viruses. The evidence from recent studies 1 suggests that rifaximin has comparable efficacy to fluoroquinolones (FQs) in non-invasive traveler's diarrhea (TD) caused by diarrheagenic E. coli. Some key points to consider when using rifaximin include:

• It is particularly effective against enteric pathogens such as Escherichia coli (including enterotoxigenic and enteroaggregative strains) 1
• It has activity against other bacteria like Staphylococcus aureus, Enterococcus species, and some anaerobes including Bacteroides species 1
• Rifaximin is less effective against Campylobacter jejuni and has limited activity against protozoa and viruses 1
• The drug works by inhibiting bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase 1
• What makes rifaximin particularly useful for GI infections is its minimal systemic absorption (less than 0.4%), allowing it to concentrate in the intestinal lumen where it can directly target intestinal pathogens while minimizing systemic side effects 1
• This makes it an excellent choice for treating traveler's diarrhea, small intestinal bacterial overgrowth (SIBO), and as a supplementary treatment in hepatic encephalopathy by reducing ammonia-producing gut bacteria 1

From the FDA Drug Label

XIFAXAN is a rifamycin antibacterial indicated for: • Treatment of travelers’ diarrhea (TD) caused by noninvasive strains of Escherichia coli in adult and pediatric patients 12 years of age and older • Reduction in risk of overt hepatic encephalopathy (HE) recurrence in adults • Treatment of irritable bowel syndrome with diarrhea (IBS-D) in adults

Limitations of Use • TD: Do not use in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to pathogens other than Escherichia coli

The GI pathogens that Rifaximin covers is Escherichia coli, specifically noninvasive strains that cause travelers’ diarrhea 2.

From the Research

Gastrointestinal Pathogens Covered by Rifaximin

Rifaximin is a gastrointestinal-selective antibiotic with a broad spectrum of antimicrobial activity against various enteropathogens, including:

• Noninvasive diarrheagenic Escherichia coli 3, 4, 5, 6
• Enterotoxigenic E. coli 5
• Enteroaggregative E. coli 5
• Shigella sonnei 5
• Clostridium difficile 3, 6, 7
• Helicobacter pylori 6

Spectrum of Antimicrobial Activity

Rifaximin has in vitro activity against:

• Gram-positive bacteria 5, 7
• Gram-negative bacteria 5, 6, 7
• Anaerobic bacteria 5, 7

Clinical Efficacy

Rifaximin is effective in the treatment of:

• Travelers' diarrhea caused by noninvasive E. coli 3, 4, 5, 6
• Acute infectious diarrhea secondary to noninvasive E. coli 4
• Small bowel bacterial overgrowth syndrome 5, 6, 7
• Hepatic encephalopathy 5, 6, 7
• Irritable bowel syndrome 7
• Functional bloating 7