What is the initial treatment for infection colitis?

Initial Treatment for Infectious Colitis

For initial treatment of infectious colitis caused by Clostridium difficile, oral vancomycin 125 mg four times daily for 10 days is the first-line therapy for both non-severe and severe cases. 1

Assessment of Disease Severity

Before initiating treatment, it's crucial to assess the severity of the infectious colitis:

Non-severe C. difficile infection:

• Stool frequency < 4 times daily
• No signs of severe colitis

Severe C. difficile infection (any of the following):

• Fever (core body temperature > 38.5°C)
• Rigors (uncontrollable shaking)
• Hemodynamic instability including signs of septic shock
• Signs of peritonitis (decreased bowel sounds, abdominal tenderness)
• Signs of ileus (vomiting, absent passage of stool)
• Marked leukocytosis (leukocyte count > 15 × 10⁹/L)
• Rise in serum creatinine (>50% above baseline)
• Pseudomembranous colitis on endoscopy
• Imaging findings: distension of large intestine, colonic wall thickening, pericolonic fat stranding 2

Treatment Algorithm

1. When oral therapy is possible:

For non-severe CDI:

• First choice: Oral vancomycin 125 mg four times daily for 10 days 1
• Alternative: Oral fidaxomicin 200 mg twice daily for 10 days 1
• If vancomycin unavailable: Oral metronidazole 500 mg three times daily for 10 days 1

For severe CDI:

• First choice: Oral vancomycin 125 mg four times daily for 10 days 2, 1

2. When oral therapy is impossible:

For non-severe CDI:

• Intravenous metronidazole 500 mg three times daily for 10 days 2, 1

For severe CDI:

• Intravenous metronidazole 500 mg three times daily for 10 days PLUS
• Intracolonic vancomycin 500 mg in 100 mL normal saline every 4-12 hours AND/OR
• Vancomycin 500 mg four times daily via nasogastric tube 2, 1

Critical Management Principles

• Always discontinue the inciting antibiotic if possible 2, 1
• Avoid antiperistaltic agents and opiates as they may mask symptoms and worsen disease 2, 1
• Monitor for treatment response within 3 days (decreased stool frequency and improved consistency) 2
• Consider surgical consultation for severe cases with perforation, toxic megacolon, or severe ileus not responding to antibiotics 2, 1

Special Considerations

For recurrent C. difficile infection:

• First recurrence: Same treatment as initial episode 1
• Second or later recurrences: Oral vancomycin 125 mg four times daily for at least 10 days, with consideration of a tapered/pulsed regimen 2, 1

For other bacterial causes of infectious colitis:

• For suspected invasive bacterial enteropathogens (Shigella, Salmonella, Campylobacter), empiric treatment with azithromycin 1000 mg as a single dose may be considered 3
• Stool cultures should be obtained before initiating antibiotics to guide targeted therapy 3

Common Pitfalls to Avoid

1. Using metronidazole as first-line treatment for severe CDI - Vancomycin has superior efficacy 1
2. Failing to discontinue the inciting antibiotic - This is crucial when possible 1
3. Not recognizing severe disease - Delays in appropriate treatment increase mortality 1
4. Not considering surgical intervention when needed - Essential in fulminant cases 1
5. Overlooking potential systemic absorption of oral vancomycin - May occur in patients with inflammatory disorders of intestinal mucosa, requiring monitoring of serum concentrations in some cases 4

Early recognition and appropriate treatment of infectious colitis are essential to reduce morbidity and mortality, with treatment choice guided by disease severity and the patient's ability to take oral medications.