What is the treatment approach for bacterial colitis?

Treatment Approach for Bacterial Colitis

For bacterial colitis, the treatment approach should be pathogen-specific, with empiric therapy using azithromycin 1000mg as a single dose for adults with febrile dysenteric diarrhea when invasive bacterial enteropathogens are suspected. 1

Diagnosis and Initial Assessment

• Diagnostic tests should include:

  • Stool culture (essential for pathogen identification)
  • Stool examination for inflammatory markers (leukocytes, lactoferrin, calprotectin)
  • Testing for specific pathogens based on clinical presentation 1
  • C. difficile toxin assay (particularly if antibiotic exposure) 2

• Key clinical features to identify:

  • Bloody, purulent, or mucoid stool
  • Fever, tenesmus, and severe abdominal pain
  • Recent antibiotic exposure (for C. difficile)
  • Travel history, food exposure, and other epidemiologic risk factors 3

Treatment Algorithm by Pathogen

1. Clostridium difficile Colitis

C. difficile is the most well-documented bacterial cause of colitis with specific treatment guidelines:

• First episode (non-severe): Metronidazole 500mg three times daily orally for 10 days 2

• First episode (severe): Vancomycin 125mg four times daily orally for 10 days 2

• If oral therapy impossible:

  • Metronidazole 500mg three times daily intravenously for 10 days
  • Consider adding intracolonic vancomycin 500mg in 100mL normal saline every 4-12 hours 2

• For recurrent C. difficile:

  • Second recurrence: Vancomycin 125mg four times daily orally for at least 10 days
  • Consider tapering/pulsed vancomycin regimen 2

• Important interventions:

  • Discontinue the inciting antibiotic if possible
  • Avoid antiperistaltic agents and opiates 2
  • Monitor for treatment response (decreased stool frequency within 3 days) 2

2. Other Bacterial Pathogens

For non-C. difficile bacterial colitis (Campylobacter, Salmonella, Shigella, E. coli, Yersinia):

• Empiric therapy for febrile dysenteric diarrhea: Azithromycin 1000mg single dose 1

• Pathogen-specific therapy once identified through culture:

  • Campylobacter: Azithromycin or fluoroquinolone (based on susceptibility)
  • Salmonella: Generally self-limiting; antibiotics only for high-risk patients
  • Shigella: Fluoroquinolone or azithromycin based on susceptibility
  • Yersinia: Fluoroquinolone or trimethoprim-sulfamethoxazole 3, 1

• Important exception: Avoid antibiotics for Shiga toxin-producing E. coli (STEC) as they may increase risk of hemolytic uremic syndrome 1

Supportive Care

• Fluid and electrolyte replacement
• Bowel rest as needed for severe symptoms
• Nutritional support if prolonged illness 3

Monitoring and Follow-up

• Assess response to treatment within 2-3 days
• Consider treatment failure if symptoms persist or worsen
• For C. difficile, monitor for recurrence (occurs in approximately 20% of cases) 2

Special Considerations

• High-risk patients (immunocompromised, elderly, severe illness) should receive antibiotics even for typically self-limiting infections 3
• Avoid antiperistaltic agents in acute infectious colitis as they may prolong bacterial carriage and worsen symptoms 2
• Surgical consultation for patients with signs of toxic megacolon, perforation, or severe disease not responding to medical therapy 2

Common Pitfalls to Avoid

• Failing to obtain appropriate cultures before starting antibiotics
• Using antibiotics for self-limiting infections in low-risk patients
• Administering antiperistaltic agents in acute infectious colitis
• Delaying treatment in severe cases
• Not testing for C. difficile in patients with recent antibiotic exposure 2, 1

The approach to bacterial colitis requires prompt identification of the causative organism through appropriate diagnostic testing, followed by targeted antimicrobial therapy based on the specific pathogen identified.