Infectious Enterocolitis

Inflammation of small/large bowel
Bact/Para/Prot/Viral

Bacterial

Pathology

1) Ingestion of toxin (Staph aureus, Clostridium perfringens)

2) Enterotoxic organisms - ingestion of organism and toxin secreted within lumen = mucosal damage (Vibrio cholera, E coli, Cl difficile)
3) Enteroinvasive organisms - ingestion of organism, which invades and damages mucosa (Salmonella, Shigella, some E coli)

 - Clostridium Difficile
Normal commensal of gut

1) Common - Antibiotic-associated colitis

Broad-spectrum ABs =
Overgrowth =
ClDiff acts as a pathogen

2) Rarer - w/o ABs
Post-surgery/Chronic illness

Ix
Macro
< inflammatory exudate

 Adheres to surface mucosa

= Pseudomembrane

Micro

< inflammation of mucosa
Neutrophils erupting from crypts - 'volcano appearance'

Parasitic & Protozoal Enterocolitis

 - Round worms
Strongyloides
Ascaris
Hookworms

 - Flatworms

Tapeworms

Flukes

 - Protozoa (seen on H&E)

Entamoeba Histolytica

Giardia lamblia

 - Entamoeba Histolytica

Faecal/Oral
Amoebas burrow into crypts
Colonic mucosa through muscularis mucosa =
Acute Dysentry

Macro

Numerous ulcers in colonic mucosa
Micro
Penetration of muscularis mucosa
Spreading out
Narrow neck
Broad base
Flask-shaped ulcers
Approx 4% of patients, parasites penetrate portal vessels
Spread haematogenously to liver
= Hepatic abscesses

*Solitary

 Up to 10cm diameter

Other abscess sites:

Lungs

Heart

Renal

Brain

Remain long after dysentry gone
Hard to Tx

 - Giardia Lamblia
Spreads via water
Attaches to small intestine mucosa
x Invasion

Pathology
Normal to blunting villi
Mixed inflamm infiltrate of Lpropria
= Malabsorptive diarrhoea


Viral Enterocolitis

Young Pts
Rotavirus

Adults
Norwalk virus (winter vomiting virus)

Immunocompromised
CMV
Acquired Immunodeficiency Virus
 - 30-60% HIV Pts = diarrhoeal illness
 - Exclusion of other pathogens
 - ?unk path/HIV