Bacterial Enterocolitis
Common sites:
- Clostridial
organsims:
- C. difficile (ex. PMC/antibiotic-associated
colitis)
- C. perfringens (ex. necrotizing jejunitis)
- C. septicum (ex.
neutropenic enterocolitis or typhlitis)
- C. botulinum (ex. botulism)
Gross features:
- C. difficile:
- Entire colon often
- Patchy or segmental maybe
- Any segment may be affected including small
bowel and appendix
- Pseudomembranes:
- Plaques of yellow fibrin and inflammatory
debris
- Atypically, may see mucosal erythema and
friability without pseudomembranes
- Erythematous mucosa
Histologic features:
- (nonspecific)
- damage to surface epithelium
- regenerative change
- decreased epithelial cell maturation
- increased mitotic
rate
- hyperemia and edema of lamina propria
- neutrophilic infiltration of lamina propria and epithelium
- with progression, may see erosion, ulceration
with severe submucosal inflammation
- C. difficile:
- “volcano” or “mushroom” lesions classically
- Mushrooming cloud of pus erupting from crypts,
which evolves into fibrinous necrotic debris
- Pseudomembranes composed of fibrin, mucin, and neutrophils
- Ballooned crypts distended with neutrophils and
mucin
- Denuded epithelium – superficial epithelial
cells often lost
- Dense neutrophilic infiltrate in lamina propria
- Occasional capillary fibrin thrombi
- If severe and prolonged, full-thickness mucosal
necrosis
- Classic features do not need to be seen – focal
active colitis may be all
- DDx ischemia:
- Hyalinized lamina propria favours
ischemia
- Crypt withering and pseudomembranes
may be seen in either
Histologic features:
- C. difficile-related colitis:
- Recurrence in up to one half despite successful
treatment
- Range of clinical disease is highly variable
References: