The Pathogenesis of Bacterial Infections

pathogenesis

all of the cellular events leading to the development of disaese

host and bacteria interactions

what is a disease

causes harm to the host

what is Koch’s fourth postulate

the same organism can be re-isolated in pure culture form the experimentally infected host

what are the host factors

host ranges - within this some individuals are susceptible and others are resistant (immune)

4 bacterial factors

infectivity

pathogenicity

virulence

transmissibility

what are the two cases of endogenous

chronic pathogens

persistent pathogens - hiding somewhere

environmental factors affecting infectivity

humidity

temperature

vector

how long is the flagellum

up to 20 micrometres

what are the bacteria avoiding

acid and bile

routes of entry

skin and mucosa

body orifices

direct injection into the bloodstream

survival outside the host

what is adhesin

adhere to host surfaces through fimbriae/pilli/adhesins

what do you need to survive in the GI

mucus

peristalsis

microflora

IgA

DCs

epithelial/tight junctions

bloodstream cells

methods of evasion

molecular mimicry

switching off irritants so no toxins

hide inside epithelial/immune cells

prevent activity of the immune response - cascades

point of a capsule

neutralise, escape and withstand phagocytosis

exotoxin heat vs endotoxin heat

exotoxin - thermolabile

endotoxin - thermostable

aggresins examples

DNases

coagulases

fibrinolysin

kinase

mucinase

lipase

protease

hyaluronidase

what is in pus

DNA protein dead immune cells host cells bacteria

two airbone diseases

TB and Anthrax