Treatment of Infectious Colitis
The treatment of infectious colitis depends primarily on the causative pathogen, with Clostridium difficile infection requiring oral vancomycin 125 mg four times daily or fidaxomicin 200 mg twice daily for 10 days as first-line therapy. 1
Diagnostic Approach
Before initiating treatment, it's crucial to identify the causative pathogen:
Stool studies:
- Multiplex PCR testing (preferred over traditional culture methods)
- Test for C. difficile toxin if recent antibiotic exposure
- Consider fecal lactoferrin/calprotectin to assess inflammation
- Blood work: CBC, CMP, and TSH
Imaging: CT scan of abdomen/pelvis for patients with severe symptoms to rule out complications like perforation or abscess
Endoscopy: Consider for patients with positive stool inflammatory markers or persistent symptoms to evaluate mucosal damage and obtain biopsies
Treatment Algorithm Based on Pathogen
1. Clostridium difficile Infection
First-line treatment:
- Oral vancomycin 125 mg four times daily for 10 days OR
- Fidaxomicin 200 mg twice daily for 10 days 1
For severe C. difficile (WBC ≥15,000 cells/mL or serum creatinine >1.5 mg/dL):
- Same regimen as above, but consider extending to 14 days if response is delayed 1
For fulminant C. difficile (hypotension, shock, ileus, megacolon):
- Vancomycin 500 mg orally/via NG tube four times daily
- Plus IV metronidazole 500 mg every 8 hours
- Add rectal vancomycin 500 mg in 100 mL saline every 6 hours if ileus present 1
Critical interventions:
- Discontinue the inciting antibiotic as soon as possible
- Avoid antiperistaltic agents and opiates
- Implement strict infection control measures (hand hygiene with soap and water, contact precautions) 1
2. Other Bacterial Pathogens (Shigella, Salmonella, Campylobacter)
- For febrile dysenteric diarrhea:
- Azithromycin 1000 mg single dose for adults 2
- Adjust based on culture results and susceptibility testing
3. Supportive Care for All Types
- Fluid and electrolyte replacement
- Nutritional support if malnourished
- Monitor for dehydration
- Thromboprophylaxis for severe cases 3
Management Based on Severity
Mild Disease (< 4 stools/day over baseline)
- Continue oral hydration
- Consider loperamide only if infection ruled out
- Monitor closely for symptom changes every 3 days 3
Moderate to Severe Disease
- Inpatient care may be necessary
- IV fluid and electrolyte replacement
- Blood transfusion to maintain hemoglobin >10 g/dL
- Daily physical examination to evaluate abdominal tenderness
- Monitor vital signs and stool frequency
- Regular laboratory monitoring (CBC, CRP, electrolytes, albumin) 3
Special Considerations
Elderly patients (>65 years): Monitor renal function during and after vancomycin treatment due to increased risk of nephrotoxicity 4
Inflammatory bowel disease: Acute colitis may be difficult to distinguish from infectious colitis; treatment with corticosteroids should not be delayed until stool microbiology results are available if IBD flare is suspected 3
Recurrent C. difficile infection: Consider vancomycin with tapered/pulsed regimen, fidaxomicin, or fecal microbiota transplantation for multiple recurrences 1
Common Pitfalls to Avoid
Delayed diagnosis: Promptly obtain stool studies in patients with suspected infectious colitis
Inappropriate use of antimotility agents: Avoid in infectious colitis until pathogen identified
Failure to discontinue the inciting antibiotic: This is crucial for C. difficile treatment success
Inadequate infection control: C. difficile requires soap and water for hand hygiene, not alcohol-based sanitizers
Overlooking severe disease markers: Monitor for signs of severe disease requiring more aggressive management (WBC ≥15,000 cells/mL, serum creatinine >1.5 mg/dL, hypotension, fever)
By following this structured approach to the diagnosis and treatment of infectious colitis, clinicians can effectively manage this common condition and prevent complications.