lecture 2 - microbial virulence Flashcards
What is pathogenicity?
The ability of a microbe to cause infection
What is virulence?
The measure of pathogenicity in a susceptible host
What is a virulence factor?
A gene product that enables colonisation of a susceptible host
What are the 2 microbe and host factors needed for an infection?
virulent microbe + susceptible host = infection
What is the name for lower virulence pathogens that require a susceptible host?
Opportunisitic pathogens
What is the name for higher virulence pathogens that do not require a susceptible host?
obligate pathogens
Where are opportunisitc pathogens found when not infectious?
The microbiome
What factors influence host susceptibility?
age, comorbidities, lifestyle, genetics, immunisation, medication, trauma , etc.
What is microbe-mediated pathogenesis?
microbial virulence factors that directly damage host cells
What is host-mediated pathogenesis?
prolonged/delayed immune responses and/or inappropriate inflammatory response that cause damage to the host itself
What are the characteristics of a gram positive cell wall?
Thick layer of peptidoglycan, with lipoteichoic and teichoic acids.
What are the characteristics of a gram negative cell wall?
Thin peptidoglycan cell wall, with an outer membrane of lipopolysaccharide.
What colour are gram-positive bacteria stained?
Purple
What colour are gram-negative bacteria stained?
pink
What is the function of biofilms & capsules in micobes?
protection from immunes cells, e.g. phagocytes, and allow for adhesion in tissues.
