Microbiology Of The Git

Front 1

List common pathogenic microbes of the Gastro-intestinal Tract that cause acute diarhoeal disease.

Back 1

Bacterial Causes (10)

• e.coli
• salmonella
• campholobacter spp.
• vibrio cholerae
• shigella
• clostridium perfringens
• Bacillus cereus
• Staphylococcus aureus
  
• vibri parhemlyticus
• yersina enterocollitica

Viral causes

• Rotavirus
• Noroviruses (formorly known as norwalk and norwalk-like viruses)

Protozoal Causes

• Giardia
• Cryptosporidium

Front 2

Most bacterial infection manifest as acute diarhoeal disease, there are however other types of GIT infection in which diarhoea is not a symptom. Name these infections...

Back 2

These include

• Helicobactor pylori

and

• Helminth infections
• hepatitis
• typhoid

Front 3

Distinguish the following terms used to describe GIT tract infections

• Gastroenteritis
• Gastritis
• dysentry
• enterocolitis

Back 3

• Gastroenteritis - Inflamation of the GIT including the stomach and intestine also a syndrome usually including: nausea, vomiting and diarhoea.
  
• Inflammation of the mucosa of the stomach
• Dysentry - An inflammatory disorder of the GIT usually accompanied by blood and pus in faeces, accompanied by symptoms of pain, fever, abdominal cramps, usually resulting from disease of the large intestine
  
• Enterocolitis - inflammation involving the mucosa of both the small and large intestine.
  

Front 4

Differentiate inflammatory diarrhoea from non inflammatory diarhoea

Back 4

Non Inflamatory - watery stools without blood. mucus or pus

Inflammatory (or dysentary) - characterised by blood, mucus and pus in stools.

Front 5

Summarise the different types of e.coli

Back 5

Enterohemoraghic e coli (EHEC) = intestinal bleeding. Cause haemorhagic uremic syndrome (HUS) - hemolytic anemia, uraemia and thrombocytopaenia. Can be life threatening. renal failure casues death in some patients. E.coli 0157 is the most common serotype associated with HUS. The main virulence factor of EHEC is the shiga toxin which causes destruction of the colonic epithelium and haemorhage.

Enterotoxigenic E.coli (ETEC) - produces heat stable and heat labile enterotoxins.

- like cholera increases cAMP resulting in massive outflow of water and electrolytes into lumen

- no inflammation

Travelers diarhea

Enteropathogenic E. coli EPEC- adheres to enterocytes causing destruction of microvilli, prevents absorption. no toxin produced.

-leading cause of diarhoea in infants. P for pediatrics

Enteroinvasive E. coli (EIEC) - Microbe invades intestinal mucosa and causes necrosis and inflammation - causes outpouring of pus blood and mucus into the lumen.

enteroaggregative