What antibiotics are used to treat infectious colitis?

Antibiotics for Infectious Colitis Treatment

For infectious colitis, oral vancomycin 125 mg four times daily for 10 days is the first-line treatment for Clostridioides difficile infection, while metronidazole and ciprofloxacin are used for other bacterial causes of infectious colitis. 1, 2

Pathogen-Specific Antibiotic Treatment

Clostridioides difficile Colitis

• First-line treatment options:

  • Oral vancomycin 125 mg four times daily for 10 days 1, 2
  • Fidaxomicin 200 mg twice daily for 10 days (alternative first-line, particularly beneficial for patients >65 years due to lower recurrence rates) 1

• Severity-based treatment:

  • Non-severe CDI: Oral vancomycin 125 mg four times daily for 10 days 1
  • Severe CDI: Oral vancomycin 125 mg four times daily for 10 days with consideration of adding IV metronidazole and surgical consultation for fulminant cases 1
  • If ileus is present: Vancomycin may be administered as a retention enema 1

Other Bacterial Causes of Infectious Colitis

• Staphylococcal enterocolitis:

  • Oral vancomycin 125-500 mg four times daily (total daily dose 500 mg to 2 g) for 7-10 days 2
  • For pediatric patients: 40 mg/kg/day in 3-4 divided doses for 7-10 days (not to exceed 2 g daily) 2

• Other bacterial pathogens:

  • Metronidazole for anaerobic infections 3, 4
  • Ciprofloxacin for gram-negative bacterial infections 5
  • Combination therapy may be needed for polymicrobial infections 5

Diagnostic Approach Before Treatment

1. Stool analysis:

   • C. difficile toxin assay
   • Stool culture
   • Multiplex PCR for enteric pathogens 5
   • Testing for parasites and viral etiologies 1

2. Laboratory tests:

   • Complete blood count
   • Renal function tests
   • Electrolytes 1

3. Consider endoscopy/colonoscopy with biopsy in moderate to severe cases 1

Risk Factors for C. difficile Infection

• Age >65 years 1
• Recent antibiotic exposure, particularly:
  • Clindamycin (highest risk, OR 35.31)
  • Fluoroquinolones (OR 30.71)
  • Cephalosporins (OR 19.02)
  • Beta-lactam/beta-lactamase inhibitor combinations (OR 9.87) 1

Management of Recurrent C. difficile Infection

• First recurrence: Same treatment as initial episode 1
• Multiple recurrences:
  • Vancomycin taper/pulse regimen
  • Fidaxomicin
  • Consider fecal microbiota transplantation (70-90% success rate) 1
  • Bezlotoxumab (monoclonal antibody) as adjunctive therapy 1

Treatment Monitoring and Pitfalls

• Monitor for treatment response:

  • If no improvement in 3-5 days, reassess diagnosis and consider alternative treatments 1
  • Delayed escalation of therapy can increase morbidity and mortality 1

• Monitor for adverse effects:

  • Nephrotoxicity (especially in patients >65 years) 2
  • Ototoxicity (with vancomycin) 2
  • Severe dermatologic reactions (TEN, SJS, DRESS, AGEP, LABD) 2

• Common pitfalls to avoid:

  • Failure to discontinue the offending antibiotic
  • Using parenteral instead of oral vancomycin for C. difficile (oral administration is required) 2
  • Not considering antibiotic resistance patterns
  • Overlooking potential systemic absorption of oral vancomycin in patients with inflammatory disorders of intestinal mucosa 2

Prevention of Recurrence

• Discontinue unnecessary antibiotics as soon as possible 1
• Consider probiotic supplementation after completion of antibiotics 1
• Patient education on antimicrobial stewardship 1
• For high-risk patients with multiple recurrences, consider prolonged vancomycin at 125 mg once daily as secondary prophylaxis 1