98 - Gastrointestinal Infections II Flashcards
When is a specific diagnosis of diarrhoea made?
When it has persisted for a while
Appearance of a microscope slide of amoebic dysentery
Few bacteria, as amoebae eat them
What does presence of Giardia trophozoites in diarrhoea mean?
Giardia hasn’t had time to encyst before being passed out of the body. Doesn’t necessarily mean that Giardia is causing disease.
What do Entamoeba histolytica eat?
RBCs
How are Cryptosporidia visualised?
Modified Ziehl-Neelsen stain
Most common form of identified bacterial diarrhoea in Australia
Salmonella
How are Salmonella found in faeces culture?
Enrichment broth (selenite)
Difficulty in identification of viral gastro
Very hard to grow in cell culture
How are viral causes of gastro often identified?
Electron microscopy, nucleic acid detection (PCR), antigen detection
Example of a viral cause of gastro that can’t be grown
Enteric adenovirus
Priority in diarrhoea treatment
Replacing fluid and electrolytes (NOT stopping diarrhoea).
Maybe reduce fluid loss.
How is water transported from gut lumen into the blood?
Passively.
Through diffusion of ions (Na+, Cl-), osmotic movement of water.
Water transport mechanism still active in diarrhoea
Na+/solute (often glucose) cotransport is still active
How can fluid loss be reduced in diarrhoea?
1
2
3
1) Anti-motility agents
2) Anti-secretory agents
3) Binding agents
Example of an anti-motility agent
Codeine (reduces peristalsis)
