What antibiotics are used to treat colitis?

Antibiotics for Colitis Treatment

For Clostridium difficile colitis, metronidazole is recommended for non-severe cases and vancomycin for severe cases, while antibiotics have a limited role in other forms of colitis except for specific infectious causes. 1, 2

Clostridium difficile-Associated Colitis

Disease Severity Assessment

• Non-severe CDI: stool frequency <4 times daily, no signs of severe colitis, white blood cell count <15 × 10^9/L 1, 2
• Severe CDI: fever, rigors, hemodynamic instability, peritonitis, ileus, marked leukocytosis (>15 × 10^9/L), elevated serum creatinine or lactate, pseudomembranous colitis on endoscopy 1, 2

Treatment Recommendations

• Non-severe CDI: metronidazole 500 mg three times daily orally for 10 days 1, 3
• Severe CDI: vancomycin 125 mg four times daily orally for 10 days 1, 4
• For recurrent CDI (second episode or later): vancomycin 125 mg four times daily orally for at least 10 days, consider taper/pulse strategy 1, 2
• If oral therapy is impossible: metronidazole 500 mg three times daily intravenously plus intracolonic vancomycin 500 mg in 100 mL normal saline every 4-12 hours 1
• Teicoplanin 100 mg twice daily can replace oral vancomycin if available 1

Special Considerations for C. difficile Colitis

• Antiperistaltic agents and opiates should be avoided 1, 3
• Discontinue the inciting antibiotic if possible 1, 3
• Consider colectomy for perforation, systemic inflammation not responding to antibiotics, toxic megacolon, or severe ileus 1, 2
• For ulcerative colitis patients with CDI (even non-severe), vancomycin-containing regimens have shown better outcomes than metronidazole alone 5

Inflammatory Bowel Disease-Associated Colitis

Ulcerative Colitis

• Antibiotics are not first-line therapy for ulcerative colitis 1
• For severe ulcerative colitis without toxicity, a trial of broad-spectrum antibiotics may be considered if no response to corticosteroids after 7 days 6
• Antibiotics show modest improvement in clinical symptoms in some studies 7

Crohn's Disease

• Antibiotics may have a modest effect in decreasing disease activity, especially with colonic involvement 7
• Ciprofloxacin and metronidazole are commonly used, particularly for perianal disease 7
• Rifaximin (non-absorbable) has shown promising results 7

Pouchitis

• Antibiotics show clinical benefit for treatment of pouchitis 7

Antibiotic-Associated Colitis (Non-C. difficile)

• Most commonly associated with clindamycin, cephalosporins, and ampicillin/amoxicillin 8
• Virtually all antibiotics except parenterally administered aminoglycosides can cause antibiotic-associated colitis 8
• Even vancomycin and metronidazole, when used parenterally, have been reported to cause this complication 8

Risks and Considerations

• Prolonged or recurrent antibiotic use can lead to significant side effects, C. difficile infection, and increasing antibiotic resistance 7
• Elderly and debilitated patients are at higher risk for antibiotic-associated pseudomembranous colitis 8
• Nosocomial acquisition of C. difficile is common; enteric isolation precautions are recommended 8
• For patients >65 years, renal function should be monitored during and after treatment with vancomycin 4

Treatment Algorithm for Colitis

1. Determine if colitis is infectious (particularly C. difficile) or inflammatory (IBD)
2. For C. difficile colitis: assess severity and treat accordingly with metronidazole or vancomycin 1, 2
3. For inflammatory colitis: antibiotics are not first-line therapy; consider trial only after failure of standard treatments 1, 7
4. For suppurative complications of Crohn's disease: drainage plus ciprofloxacin, metronidazole, or combination 7