Treatment of Bacterial Colitis
For Clostridioides difficile colitis, treat non-severe disease with oral metronidazole 500 mg three times daily for 10 days and severe disease with oral vancomycin 125 mg four times daily for 10 days. 1, 2, 3
Disease Severity Assessment for C. difficile Colitis
Before initiating treatment, assess disease severity to guide antibiotic selection:
Non-severe disease is characterized by: 1, 3, 4
- Stool frequency <4 times daily
- White blood cell count <15 × 10⁹/L
- Absence of systemic inflammatory signs
Severe disease includes any of the following: 1, 2, 3
- Fever >38.5°C with rigors
- Hemodynamic instability or septic shock
- Signs of peritonitis (decreased bowel sounds, abdominal tenderness, rebound, guarding)
- Signs of ileus (vomiting, absent stool passage)
- Marked leukocytosis (>15 × 10⁹/L) or left shift (>20% band neutrophils)
- Serum creatinine rise >50% above baseline
- Elevated serum lactate
- Pseudomembranous colitis on endoscopy
- Colonic distension or wall thickening on imaging
First-Line Antibiotic Treatment Algorithm
For Non-Severe C. difficile Colitis:
Oral metronidazole 500 mg three times daily for 10 days 1, 2, 3, 5
For Severe C. difficile Colitis:
Oral vancomycin 125 mg four times daily for 10 days 1, 2, 3, 5
When Oral Therapy is Impossible:
For severe disease when oral administration is not feasible: 1, 2
- IV 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 by nasogastric tube
Treatment of Recurrent C. difficile Infection
First Recurrence:
Treat the same as the initial episode based on severity (metronidazole for non-severe, vancomycin for severe) 1, 3
Second and Subsequent Recurrences:
Oral vancomycin 125 mg four times daily for at least 10 days, with consideration of a taper/pulse strategy 1, 2, 3, 4
Taper/pulse strategies include: 1
- Decreasing daily dose by 125 mg every 3 days, or
- A dose of 125 mg every 3 days for 3 weeks
Multiple Recurrences Unresponsive to Antibiotics:
Fecal microbiota transplantation (FMT) is strongly recommended, with 70-90% success rates 3, 4
Critical Management Principles
Immediately discontinue the inciting antibiotic if the colitis was clearly induced by antibiotic use, particularly in mild cases 1, 2, 3, 4
Avoid antiperistaltic agents (loperamide, diphenoxylate) and opiates entirely, as they can precipitate toxic megacolon 1, 2, 3, 4
Narrow antibiotic spectrum when possible based on culture results to minimize further disruption of gut flora 1
Surgical Intervention Criteria
Colectomy should be performed urgently for: 1, 2, 3, 4
- Perforation of the colon
- Toxic megacolon
- Severe ileus
- Systemic inflammation with deteriorating clinical condition not responding to antibiotic therapy
- Operate before serum lactate exceeds 5.0 mmol/L 1, 2
Treatment of Other Bacterial Colitis
For non-C. difficile bacterial colitis (Campylobacter, Salmonella, Shigella, E. coli, Yersinia): 6, 7, 8
Empiric treatment for febrile dysenteric diarrhea: azithromycin 1000 mg as a single dose for suspected invasive bacterial enteropathogens (Shigella, Salmonella, Campylobacter) 7
Standard stool culture should be performed to identify the specific pathogen and guide pathogen-specific antimicrobial therapy 7, 8
Do not use antibiotics for Shiga toxin-producing E. coli (STEC), as antimicrobial therapy may increase risk of hemolytic uremic syndrome 7
Common Pitfalls to Avoid
Do not use parenteral vancomycin for C. difficile colitis, as it is not excreted into the colon and is ineffective 1, 5
Do not repeat stool testing after treatment to assess response; clinical improvement (decreased stool frequency, improved consistency) is the primary measure of success 1, 4
Do not delay surgery in severe cases waiting for antibiotic response; early colectomy improves outcomes 1, 3
Monitor renal function in patients >65 years of age during and following treatment, as nephrotoxicity can occur with oral vancomycin 5