L3.6 Bacterial Pathogenesis Flashcards
1
Q
How do epithelial cells penetrate the cell?
A
Pathogen mediated endocytosis or bacterial surface proteins - encourage cells to take them up
2
Q
What are the features of yersinia?
A
- Can cause gut infections
- Gram negative rod closely related to E. coli
- Invasin protein on outer membrane surface
- Tricks M cells (in gut) to think that are an antigen and signal via the M cell to activate the cytoskeleton so that the M cell becomes endocytic (takes up whole bacteria)
3
Q
What are the features of shigella?
A
- form of E.coli
- Colon
- moves through M cells into sub epithelial layer then reinvades the epithelium through the basal aspect
4
Q
What happens if the bacteria translocate the epithelium?
A
- Evade phagocytosis: pyogenic bacteria,
- Resist killing: facultative intracellular pathogens (viruses, bacteria, typhus fever, chlamydia)
5
Q
What are leukocidins?
A
Molecules that kill white cells
6
Q
What are the features of the pneumococcus vaccine?
A
- Adult: direct antigen polysaccharide from 23 types of capsule
- Child: 12 valent purified forms of antigen
7
Q
How can bacteria overcome adaptive immunity?
A
Immunosupression
Expression of weal antigens
Antigenic diverisity
Antigen modification
8
Q
What is autoclaving and what does it kill?
A
Heating for a certain time - kills all bacteria but not endotoxins
9
Q
What are the features of endotoxins?
A
Produced by dying cells Part of cell wall LPS Highly resistance to heat Variable antigenicity Not neutralised by antibodies Not toxoids Moderate potency - 1um would kill Non specific action
