My Clinical Notes

Viral enterocolitis

 

• Incubation period ranges from 1 to 7 or more days
• Besides diarrhoea, fever, anorexia and headache can occur
• Causes;
  • Rotavirus (group A)
    • Most common in children aged 6 to 24 months – most common at the time of weaning
    • Encapsulated double standed RNA virus
    • Infects and destroys mature enterocytes in the small intestine
  • Enteric adenoviruses
    • Infection causes atrophy of the villi and crypt hyperplasia
    • Causes colitis as well as enteritis
  • Caliciviruses
    • Two types, Sapporo-like viruses and Norwalk-like viruses
    • Norwalk is more common and is responsible for the majority of food borne epidemic gastroenteritis is all age groups

 

Bacterial enterocolitis

 

• Mechanisms;
  • Ingestion of a preformed toxin
  • Infection of a toxigenic organism
  • Infection by a enteroinvasive organism

• Most bacterial infections exhibit a non-specific pattern of damage to the surface epithelium, decreased epithelial cell maturation and an increase in the mitotic rate – termed regenerative change, hyperaemia and oedema of the LP and variable neutrophil infiltration of the LP and epithelial layer

 

Shigella bacillary dysentery

• Shigella spp are gram negative facultative anaerobes
• Faecal oral transmission
• Invades intestinal mucosal cells but doesn’t go beyond the LP
• Dysentery is caused by the  bacteria escaping the epithelial cell phagolysosome and multiplying within the cell cytoplasm destroying the cell
• Shiga toxin produces haemorrhagic colitis and haemolytic syndrome by damaging the endothelial cell in the microvasculature of the colon and glomeruli
• Generally affects the distal colon

 

Salmonellosis and typhoid fever

• Salmonellae are flagellated gram negative bacteria
• S.typhimurium and S.enteritidis contaminate beef and chicken and cause food and water born gasteroenteritis
• S.typhi causes a systemic illness marked by fever and systemic symptoms
• Ileum and colon are inflamed with Peyer patch involvement

 

Camphylobacter enterocolitis

• Comma shaped flagellated gram negative
• Infection may result in diarrhoea, dysentery and enteric fever when the bacteria replicate in the LP and MLN
• Post infectious complications include reactive arthritis and Guillain-Barre

 

Cholera

• Comma shaped gram negative bacteria
• Never invade the epithelium, instead remain in the lumen and secrete and enterotoxin
• Therefore there is no histological abnormality with the intestine
• Secretogue toxin results in activation of adenylate cyclase – results in rice water diarrhoea

 

Pseudomembraneous colitis

 

• Acute colitis characterised by the formation of an adherent layer of inflammatory cells and debris overlying sites of mucosal injury, e.g. a pseudomembrane
• It is usually caused by the toxins of Clostridium difficile
• It occurs in patients without a background of chronic colitis, following a course of broad spectrum antibiotic disease, toxin forming strains may flourish following the alteration of the intestinal flora
• Rarely it may occur in the absence of antibiotic therapy, typically after surgery or superimposed on a chronic debilitating illness
• Infrequently the small intestine may be involved
• Diagnosis is generally confirmed following detection of C.diff cytotoxin the stool
• Histologically the surface epithelial is denuded and the superficial LP contains a dense infiltrate of neutrophils and occasional capillary fibrin thrombi
• Superficially damage crypts are distended by a mucopurulent exudates which erupts out of the crypts to form a mushrooming cloud that adheres to the damaged surface – the cloud coalesces to form the pseudomembrane

This entry was posted on Wednesday, February 27th, 2008 at 2:13 pm and is filed under Gastrointestinal. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.