Bacterial pathogenesis - L5A Flashcards
what is an infection?
growth of micro-organisms within a host
what is a disease
damage that impairs host function
what is a pathogen
microorganism capable of causing disease
what is pathogenesis
process of disease
what is adhesion
ability of a microbe to attach to a surface
what is adhesins
bacterial factors mediating adherence
what’s colonisation
growth of microoganism in host
what does subclinical mean
asymptomatic infection
what is latent?
an infection with the potential to become active
what does opportunistic mean
infection caused by a microorganism that would not normally cause disease in a healthy host
what is pyogenic
pus forming microorganisms
what is fulminant
sudden and rapidly developing infections
infection process:
- exposure
- adherence
- invasion
- multiplication
what did Robert Koch work with?
bacillus anthracis (anthrax)
what did Robert koch show?
- Showed bacilli always present in those with infection
- merely correlative and wanted to prove causation
what was Koch’s four hypothesis?
- the pure culture grown must produce the same disease when inoculated into a healthy animal
- the same microbe must be re-isolated from the experimentally infected animal
- microbe must be present
- microbe should be isolated from host
why was koch’s hypothesis revolutionary
- mostly hold true
- opened door to new treatments
why do microbes use receptors?
stick to and enter cells
replicate on the cell surface
why do some bacteria have extensions?
they mediate attachment
why do some bacteria have extensions?
they mediate attachment
where does colonisation begin?
on mucous membranes
what is invasion?
Ability of pathogen to enter into tissues and cause disease
2 things infections can be
localised or systemic
give an example of a localised infections
staphylococcus aureus skin boil
give an example of systemic infection
septicaemia
what leads to septicaemia
If bacteria multiply in bloodstream and spread this can be fatal
is staphylococcus aureus gram + or -
positive
give facts about staphylococcus aureus
- Spreads into cell cytoplasm
- Quickly invades range of cell types
- Replicated intracellularly in small vacuoles
what’s virulence
The outcome of the interaction between host and pathogen
what are virulence factors?
Factors promoting host damage
is virulence measurable?
yes
give examples of virulence factors?
- toxins
- pili
- capsule
what is toxicity?
ability to cause disease by a toxin
what are exotoxins?
toxic proteins released from pathogen as it grows
what are endotoxins?
toxic lipopolysaccharide in gram negative bacteria
what is enterotoxin
site of action is small intenstine
what are the 3 classes of exotoxins?
- AB toxins
- cytolytic toxins
- superantigen toxins
what does the B subunit do in AB toxins?
binds to host cell molecule
what does the A subunit do in AB toxins
across cytoplasmic membrane where it damages cell
what do the cytolytic toxins do?
damage host cell membranes and kill cells
what do superantigen toxins
drive cytokine storms
give an example of a skin infection:
streptococcus pyogenes
give an example of a respiratory infection:
Haemophilus influenzae:
give an example of a gastrointestinal infection
Campylobacter jejuni:
