Infectious Causes of Jejunal Colitis
Critical Clarification
The term "jejunal colitis" is anatomically contradictory—the jejunum is small bowel, while colitis refers to large bowel (colon) inflammation. I will address infectious causes of jejunal enteritis (small bowel inflammation) and infectious colitis (large bowel inflammation) separately, as the pathogens and clinical presentations differ significantly.
Infectious Jejunal Enteritis (Small Bowel)
Primary Pathogens
Parasitic infections dominate jejunal disease:
- Giardia lamblia causes non-inflammatory diarrhea affecting the proximal small bowel, diagnosed by fluorescence or EIA testing 1
- Cryptosporidium identified through acid-fast stains, particularly in immunocompromised patients 1
- Cyclospora, Isospora detected via acid-fast staining 1
- Microsporidia requires special chromotrope stains 1
Bacterial causes are less common in isolated jejunal disease:
- Vibrio species should be considered with seafood or seacoast exposure 1
- Yersinia enterocolitica when persistent abdominal pain and fever are present, requiring cold enrichment culture 1
Diagnostic Approach for Jejunal Disease
Order parasitic studies when:
- Travel to endemic areas 1
- Non-inflammatory diarrhea pattern (watery without blood/pus) 2
- Immunocompromised status 1
Infectious Colitis (Large Bowel)
Common Bacterial Pathogens
The most frequent invasive bacterial causes include:
- Campylobacter jejuni 2, 3
- Salmonella species 2, 3
- Shigella species 2, 3
- Shiga toxin-producing E. coli (STEC) O157:H7 2
- Clostridioides difficile 4, 5
- Yersinia enterocolitica 3
Less common bacterial causes:
- Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum in men who have sex with men with proctitis 1, 6
Viral Pathogens
- Cytomegalovirus (especially immunocompromised) 6
- Rotavirus, adenovirus, norovirus 6
- Herpesvirus (distal proctitis in homosexual men) 1
Parasitic Causes
Recommended Diagnostic Algorithm
Initial Stool Testing (All Patients)
Obtain these studies immediately:
- Standard bacterial culture or PCR panel for Shigella, Salmonella, Campylobacter 4
- C. difficile toxin assay is mandatory for every case, especially with recent antibiotic exposure, immunosuppression, or corticosteroid use 4, 5
- Shiga toxin testing when STEC suspected (low-grade or absent fever with bloody diarrhea) 4, 2
Inflammatory Markers
Document colonic inflammation:
- Fecal lactoferrin or microscopy for leukocytes indicates invasive colitis 1, 2
- Complete blood count may show leukocytosis or leukemoid reaction (especially Shigella) 4
- Serum CRP and ESR typically elevated but cannot distinguish infection from IBD 4
Specialized Testing Based on Epidemiology
Order parasitic studies when:
- Travel history to endemic regions 1, 4
- Fluorescence and EIA for Giardia and Cryptosporidium 1
- Acid-fast stains for Cryptosporidium, Cyclospora, Isospora 1
- Ova and parasite examination 4
Consider additional cultures:
- Vibrio species with seafood/seacoast exposure 1
- Yersinia with persistent abdominal pain and fever (requires cold enrichment) 1
Endoscopic Evaluation
Perform sigmoidoscopy or colonoscopy with biopsies when:
- Diagnosis remains uncertain after stool studies 4
- Need to differentiate infectious colitis from IBD 4
- Infectious colitis shows preserved crypt architecture with acute inflammatory infiltrates 4
- IBD demonstrates crypt architectural distortion, basal plasmacytosis, and chronic inflammation 4
Management Principles
Antimicrobial Therapy
Critical treatment decisions:
- Never give antibiotics for STEC infection—this increases hemolytic uremic syndrome risk 4, 5, 2
- For empiric treatment of febrile dysenteric diarrhea, treat adults with azithromycin 1000mg single dose targeting Shigella, Salmonella, Campylobacter 2
- C. difficile first-line therapy: oral vancomycin 125mg QID × 10 days or fidaxomicin 200mg BID × 10 days 5
- Antibiotics for invasive bacterial colitis should be reserved for severe infections, immunocompromised patients, prosthetic devices/valvular disease, elderly (>65 years), or significant comorbidities 5
Supportive Care
All patients require:
- Aggressive IV fluid resuscitation for volume depletion 5
- Electrolyte replacement (potassium, magnesium) as needed 5
- Avoid antidiarrheal agents—they can precipitate toxic megacolon 5
Critical Pitfalls to Avoid
- Do not use metronidazole as first-line for C. difficile—vancomycin or fidaxomicin are superior 5
- Do not continue the inciting antibiotic in C. difficile infection—this dramatically increases recurrence 5
- Early IBD can mimic infection by preserving crypt architecture; repeat endoscopy after 4 weeks if diagnostic doubt persists 4
- Reassess at 3 days if no improvement; reconsider diagnosis and retest for C. difficile if not already done 5
- Persistent symptoms ≥14 days warrant evaluation for IBD or post-infectious complications 4