What antibiotic is used to treat colitis?

Antibiotic Treatment for Colitis

For colitis caused by Clostridium difficile infection, metronidazole 500 mg three times daily orally for 10 days is recommended for non-severe cases, while vancomycin 125 mg four times daily orally for 10 days is recommended for severe cases. 1, 2

Types of Colitis and First-Line Antibiotic Choices

Clostridium difficile-Associated Colitis

• Non-severe C. difficile colitis (stool frequency <4 times daily, no signs of severe colitis):

  • Metronidazole 500 mg three times daily orally for 10 days 1, 2
  • If oral therapy is impossible: metronidazole 500 mg three times daily intravenously for 10 days 1

• Severe C. difficile colitis (fever, rigors, hemodynamic instability, peritonitis, ileus, marked leukocytosis, elevated creatinine or lactate):

  • Vancomycin 125 mg four times daily orally for 10 days 1, 2, 3
  • 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

Recurrent C. difficile Colitis

• First recurrence: Same treatment as initial episode 1
• Second or subsequent recurrences:
  • Vancomycin 125 mg four times daily orally for at least 10 days 1, 2
  • Consider vancomycin taper/pulse strategy (decreasing daily dose with 125 mg every 3 days or a dose every 3 days for 3 weeks) 1

Ulcerative Colitis

• No antibiotic regimen is generally recommended for active ulcerative colitis, including acute severe disease 1
• Single-agent antibiotic therapy has shown very limited value in ulcerative colitis 1
• Combination antibiotic therapy has shown some promise in mild to moderately severe active disease, but evidence is insufficient for a firm recommendation 1

Special Considerations

Severity Assessment for C. difficile Colitis

• Assess disease severity to guide treatment choice 2
• Factors indicating severe disease: fever, rigors, hemodynamic instability, signs of peritonitis, ileus, marked leukocytosis, rise in serum creatinine, elevated serum lactate, or pseudomembranous colitis on endoscopy 2

Important Precautions

• Avoid antiperistaltic agents and opiates in C. difficile infection 1, 2
• Discontinue the inciting antibiotic if possible 1, 4
• For mild C. difficile colitis clearly induced by antibiotics, stopping the inducing antibiotic may be sufficient, but observe closely for clinical deterioration 1
• Consider colectomy for perforation of the colon, systemic inflammation with deteriorating clinical condition not responding to antibiotics, toxic megacolon, or severe ileus 1, 2

Monitoring and Follow-up

• In patients >65 years of age, monitor renal function during and following treatment with oral vancomycin due to risk of nephrotoxicity 3
• Expect improvement within three days after starting appropriate antibiotic therapy, but be aware that approximately 20% of patients may experience relapse 4

Alternative Antibiotics

• Teicoplanin 100 mg twice daily may replace oral vancomycin if available 1
• Fidaxomicin 200 mg twice daily for 10 days is an option for recurrent C. difficile infection 2
• Bacitracin has been used successfully in some cases (25,000 units four times daily for 7-10 days) but is not first-line therapy 5

Treatment Pitfalls to Avoid

• Do not use vancomycin indiscriminately due to risk of promoting vancomycin-resistant bacteria 4
• Do not assume all antibiotic-associated diarrhea is C. difficile infection; confirm diagnosis with stool tests for C. difficile toxins 6
• Do not forget to implement enteric isolation precautions for patients with C. difficile infection to prevent nosocomial spread 7
• Do not continue the inciting antibiotic if it can be safely discontinued 4, 8
• Do not use oral vancomycin for infections other than C. difficile or staphylococcal enterocolitis, as it is not effective for other types of infections 3