Management of Infectious Colitis
For most cases of infectious colitis in adults, supportive care without antibiotics is recommended, as the vast majority are self-limited and the modest benefits of antimicrobial therapy are outweighed by risks including prolonged bacterial shedding and resistance. 1
Initial Diagnostic Approach
Identify the clinical pattern to guide management:
- Bloody diarrhea with fever, abdominal pain, or vomiting suggests invasive/inflammatory pathogens (Salmonella, Campylobacter, C. difficile, Shigella, STEC) 1
- Bloody diarrhea with minimal or absent fever should raise suspicion for STEC infection 1
- Obtain stool studies including multiplex PCR followed by guided culture on PCR-positive pathogens for antibiotic susceptibility testing 2
- Look for inflammatory markers (fecal leukocytes, lactoferrin, or calprotectin) to confirm inflammatory diarrhea 3
Antibiotic Decision Algorithm
DO NOT TREAT with antibiotics:
- STEC O157 or any STEC producing Shiga toxin 2 - avoid fluoroquinolones, β-lactams, TMP-SMX, metronidazole, and macrolides due to evidence of harm 1
- Most cases of proven Salmonella gastroenteritis - antibiotics increase prolonged shedding and are not recommended for uncomplicated cases 1
- Campylobacter infection - benefit is small (average 1 day shorter symptoms) and treatment promotes quinolone-resistant shedding 1
TREAT with antibiotics:
Severe infections or immunocompromised hosts - these are the primary exceptions where treatment benefits outweigh risks 1
Empiric therapy for febrile dysentery (when STEC is not suspected):
- Azithromycin 1000mg single dose for suspected invasive bacterial pathogens (Shigella, Salmonella, Campylobacter) 3
- Fluoroquinolones showed average 1-day reduction in symptoms in RCTs, but resistance concerns limit current use 1
Pathogen-specific therapy once identified:
- Initiate antimicrobial therapy for all confirmed infectious colitis except STEC 3
- Enteric fever (typhoid) - early treatment improves outcomes with reduced intestinal perforation and mortality compared to pre-antibiotic era 1
Critical Pitfalls to Avoid
C. difficile considerations:
- CDI incidence has doubled since 2001 and can mimic other infectious colitis 1
- Community-acquired cases increasingly occur with minimal antibiotic exposure 1
- Concomitant antimicrobial use decreases cure rates and increases relapse rates 1
STEC management errors:
- Because Shiga toxin profile is often unknown when treatment is considered, and no clear benefit exists for treating less virulent STEC, avoid all antibiotics when STEC is in the differential 1
- This is particularly important in bloody diarrhea with absent or low-grade fever 1
Supportive Care
All patients require: