Immunity to bacteria

Question 1

How does pneumococcus evade phagocytosis?

Answer 1

Thick polysaccharide coat around cell wall blocks complement binding.
Immune response relies on opsonisation to make phagocytosis possible -> problem for people w antibody deficiency

Question 2

Pneumococcus

Answer 2

Streptococcus pneumoniae
Gram positive
>90 serotypes
> I million deaths per year

Question 3

Contact transmission methods

Answer 3

direct contact
indirect contact by fomites
droplets

Question 4

Vehicle transmission methods

Answer 4

waterborne
foodborne
airborne, including dust particles

Question 5

Pneumococcus - pneumolysin

Answer 5

Protein toxin produced by all clinical isolates
Released upon cell lysis
Can bind to and lyse all cells that have cholesterol in their membranes
Known to cause pro-inflammatory activities at sub-lytic concentrations

Question 6

Inflammatory

Answer 6

CD4 T cell proliferation
Inflammasome activation
Epithelial phospholipase A and arachidonic acid release
Macrophage NO production
Cytokine and chemokine upregulation

Question 7

Tolerogenic

Answer 7

Treg responses
Complement depletion
Reduced neutrophil killing
Dendritic cell apoptosis

Question 8

Particulate inhalation and high temp combine to provide conditions conducive to bacterial invasive disease:

Answer 8

Reduced phagocytic killing
Increased release of tissue damaging toxins
Increased inflammation
Reduced Tregs