What is the treatment for infectious colitis?

Treatment of Infectious Colitis

The treatment of infectious colitis depends on the specific pathogen identified, with metronidazole 500 mg three times daily orally for 10 days recommended for non-severe Clostridium difficile infection (CDI) and vancomycin 125 mg four times daily orally for 10 days recommended for severe CDI. 1

Diagnostic Approach

Before initiating treatment, proper diagnosis is essential:

• Stool testing should be performed to identify the causative pathogen, with multiplex PCR being preferred for rapid identification 2, 3
• Evaluate for signs of severe colitis including fever >38.5°C, rigors, hemodynamic instability, peritonitis, ileus, marked leukocytosis, elevated creatinine, and elevated lactate 1
• Consider recent antibiotic exposure as a risk factor for C. difficile infection 3
• Bloody diarrhea in young adults with decreased response to antibiotics may suggest inflammatory bowel disease with concurrent infection rather than pure infectious colitis 4

Treatment Algorithm Based on Pathogen

Clostridium difficile Infection (CDI)

1. Initial episode or first recurrence:

   • Non-severe CDI (stool frequency <4 times daily, no signs of severe colitis):

     • Metronidazole 500 mg three times daily orally for 10 days (A-I) 1
     • If oral therapy impossible: Metronidazole 500 mg three times daily intravenously for 10 days (A-III) 1

   • Severe CDI (presence of severe colitis signs):

     • Vancomycin 125 mg four times daily orally for 10 days (A-I) 1
     • If oral therapy impossible: Metronidazole 500 mg three times daily intravenously PLUS intracolonic vancomycin 500 mg in 100 mL saline every 4-12 hours and/or vancomycin 500 mg four times daily by nasogastric tube (A-III, C-III) 1

2. Second or later recurrences:

   • Vancomycin 125 mg four times daily orally for at least 10 days (B-II) 1
   • Consider vancomycin taper/pulse strategy (B-II) 1

3. Surgical intervention is indicated for:

   • Perforation of the colon
   • Systemic inflammation not responding to antibiotics
   • Toxic megacolon or severe ileus
   • Consider before serum lactate exceeds 5.0 mmol/L 1

Other Bacterial Pathogens

• For febrile dysenteric diarrhea (suspecting Shigella, Salmonella, or Campylobacter): Azithromycin 1000 mg single dose empirically 5
• Pathogen-specific antimicrobial therapy should be initiated once laboratory diagnosis is made 5
• Avoid antimicrobial therapy for Shiga toxin-producing E. coli (STEC) 5

General Management Principles

• Avoid antiperistaltic agents and opiates as they may worsen the condition (B-II) 1
• Use antibiotics with the narrowest effective spectrum and adjust based on culture results (B-III) 1
• Mild CDI clearly induced by antibiotics may be treated by stopping the inducing antibiotic, with close monitoring (B-III) 1
• Provide appropriate hydration (oral, nasogastric, or intravenous) based on severity 3
• Monitor for treatment response: decreased stool frequency, improved stool consistency after 3 days, and no new signs of severe colitis 1

Special Considerations

• Patients >65 years require monitoring of renal function during and after treatment with vancomycin due to increased risk of nephrotoxicity 6
• Patients with inflammatory disorders of the intestinal mucosa may have significant systemic absorption of oral vancomycin 6
• Watch for severe dermatologic reactions with vancomycin including toxic epidermal necrolysis, Stevens-Johnson syndrome, and drug reaction with eosinophilia 6
• Approximately 9% of patients with acute gastroenteritis or colitis develop post-infectious irritable bowel syndrome 3

Treatment Failure and Recurrence

• Treatment failure is defined as absence of CDI treatment response 1
• Recurrence is characterized by increased stool frequency for two consecutive days with looser stools or new signs of severe colitis, plus microbiological evidence of toxin-producing C. difficile 1
• For recurrent infections, consider vancomycin with taper/pulse strategy 1