Week 2: Listeria Monocytogenes Flashcards
1
Q
Listeria Monocytogenes
A
- Gram positive motile rod
- Causes serious food-borne infections
- 5-10% of adults are symptomatic carriers
- Found in water, sewage + earth/soil
- One of the few bacteria that can cross the placenta, but will not always result in the infection of the foetus
2
Q
L. monocytogenes diseases/conditions
A
- In the average healthy adult, L. monocytogenes will cause flu like symptoms, but less commonly (+ importantly) diarrhoea + abdominal pain
- But can cause much more serious infections with underlying weakness in their immune systems from
+ HIV/AIDs
+ Chemotherapy
+ Cancer
+ Diabetes
+ Old age
+ Alcoholism
3
Q
General pathogenesis
A
- Bacteria acquired by ingestion
- Adhere to intestinal mucosa
- Invade cells of intestinal mucosa
- Propagates within cells
- Systemic spread within the host
4
Q
Internalin A (InlA)
A
- InlA is involved in the adhesion + invasion of the cell
- Aids in crossing intestinal + maternofetal barriers
- InlA is covalently attached to cell wall;
- Binds to host protein E-cadherin
5
Q
Internalin B (InlB)
A
- Promotes entry of L. monocytogenes into:
+ Epithelial cells
+ Endothelial cells
+ Hepatocytes
+ FIbroblasts - Protein is non-covalently bound to cell wall
- Can also be released into extracellular environment to act as a soluble factor affecting host cell signalling
- Doesn’t have a role in pathogen entry
6
Q
Listeriolysin (LLO)
A
- A pore-forming toxin
- Its action is cholesterol-dependent + tightly controlled
- Largely responsible for medicating rupture of phagosomal membrane
