L2 - Bacterial pathogens and disease 2 (Endotoxins)

Question 1

What is an Endotoxin?

Answer 1

It is a toxin in the bacterial cell wall
AKA lipopolysacchrides:
made up of a lipid and polysaccharide (O antigen)

Question 2

What are some characteristics of endotoxins?

Answer 2

Lipid A - active component that is not immunogenic

O antigen is highly immunogenic and immune specific

found only in gram negative bacteria

heat stable

not converted to toxoids

major initiator of the sepsis pathway

Question 3

What is sepsis?

Answer 3

“Life threatening organ dysfunction caused by a dysregulated host response to infection”.

Question 4

Describe dysregulation of organs during sepsis?

Answer 4

Production of reactive oxygen species (ROS) – Hydroxyl and nitric oxide – damages cellular proteins, DNA and lipids and impairs mitochondria.
Complement activation (esp. C5a) – increase ROS, granulocyte enzyme release, endothelial permeability and tissue factor expression.
Widespread immunothrombosis leading to disseminated intravascular coagulation (DIC) with impaired microvasculature function and organ dysfunction. 
Mitochondrial damage leads to decreased intracellular ATP and cells enter state of hibernation – exacerbates organ dysfunction.