What is the treatment for infectious colitis?

Treatment of Infectious Colitis

The treatment of infectious colitis depends on the specific pathogen, with Clostridioides difficile colitis requiring oral vancomycin 125 mg four times daily for 10 days as first-line therapy, while other bacterial causes typically require targeted antibiotics such as azithromycin for invasive pathogens like Shigella, Salmonella, and Campylobacter. 1, 2, 3

Diagnosis and Assessment

• Diagnosis requires:

  • Stool culture and/or multiplex PCR to identify specific pathogens
  • Assessment for inflammatory markers (leukocytes, lactoferrin, calprotectin)
  • Evaluation for fever, dysentery, and colonic inflammation 4, 3

• Severity assessment should include:

  • Vital signs (fever >38.5°C, tachycardia)
  • Laboratory values (leukocytosis >15×10⁹/L, elevated creatinine, elevated lactate)
  • Signs of peritonitis or ileus
  • Imaging findings (colonic distension, wall thickening) 1

Treatment Algorithm by Pathogen

1. Clostridioides difficile Colitis

• Non-severe disease:

  • Oral metronidazole 500 mg three times daily for 10 days 1

• Severe disease:

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

• If oral therapy impossible:

  • 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 1

• Fulminant colitis (toxic megacolon, severe systemic inflammation):

  • High-dose vancomycin 500 mg orally six times daily PLUS
  • Intravenous metronidazole 500 mg every 8 hours 1
  • Consider surgical consultation for possible colectomy 1

2. Other Bacterial Pathogens (Shigella, Salmonella, Campylobacter)

• Empiric treatment for febrile dysenteric diarrhea:

  • Azithromycin 1000 mg single dose for adults 3

• Pathogen-specific therapy once identified through culture or PCR 4, 3

Special Considerations

Severe Ulcerative Colitis

If infectious colitis is ruled out and inflammatory bowel disease is diagnosed:

• First-line treatment:

  • Intravenous corticosteroids (methylprednisolone 60 mg/day or hydrocortisone 100 mg four times daily) 1, 5

• For non-responders after 3-5 days:

  • Consider rescue therapy with ciclosporin or infliximab 1, 6, 7

• Supportive care:

  • Subcutaneous prophylactic low-molecular-weight heparin
  • Nutritional support (enteral preferred over parenteral)
  • Fluid and electrolyte replacement
  • Blood transfusion if hemoglobin <8-10 g/dL 1

Surgical Indications

• Perforation of the colon
• Toxic megacolon unresponsive to medical therapy
• Severe systemic inflammation not responding to antibiotics
• Consider surgery before serum lactate exceeds 5.0 mmol/L 1

Important Cautions

• Avoid antiperistaltic agents and opiates as they may worsen colitis and precipitate toxic megacolon 1
• Discontinue unnecessary antibiotics that may be triggering or worsening C. difficile infection 1
• Monitor closely for treatment failure (absence of response after 3 days) 1
• For recurrent C. difficile infections, consider vancomycin taper/pulse strategies 1
• Nephrotoxicity risk is increased with oral vancomycin in patients >65 years; monitor renal function 2

By following this algorithm and tailoring treatment to the specific pathogen and disease severity, most cases of infectious colitis can be effectively managed with appropriate antimicrobial therapy and supportive care.