Microbial Mechanisms of Pathogenicity Flashcards
Define pathogens
Disease causing microorganism
Define pathogenicity
ability to cause disease
Define virulence
degree of pathogenicity
Define infection
when body is invaded by a harmful microorganism
Define disease
when the health of the human body is affected by an infection
What are 3 portals of entry
1) mucous membrane
2) skin
3) parenteral route
What us the easiest and most common entry
respiratory tract ( mucous membrane)
Define ID50
infectious dose for 50% of a sample population
measures virulence of a microbes
Define LD50
lethal dose for 50% of a sample population
measures potency of a toxin
What are 2 ways of adherence of microorganisms to Host cells
1) Surface molecules on the pathogens
2) bind to complementary surface receptors of host cell
Describe surface molecules on the pathogens
adhesins or ligands
located on glycocalyx or fimbraie or pili
glycoproteins or lipoproteins
Define bind to compementary surface receptors of host cell
mannose-sugar
What are 4 ways pathogens pentrate host defenses
1) capsules
2) cell wall components
3) enzymes
4) antigenic variation
Describe capsules as a way to penetrate host defenses
glycocalyx around the cell wall
impair phagocytosis ( streptococcus pneumoniae, haemophilus influenza,bacillus anthracis)
have capsule increased virulence
body can create antibodies against capsules
Describe cell wall components to penetrate host defenses
1) M protein resists phagocytosis
2) Opa protein
3) waxy lipid ( mycolic acid) resists digestion
Describe how M protein resists phagocytosis
streptococcus pyogenes
produce heat resistence and resistent proteins
Describe Opa protein as away to penetrates host defenses
Neisseria gohorrhoeae
attach to host cell
use fimbrae and outer membrane protein
inhibit T helper cell
Describe waxy lipid as a wayof penetrating host defenses
resists digestion
ex: mycobacterium tuberculosis
has ability to divide in microphage
What are 5 enzymes used to penetrate host defenses
1) Coagulases
2) Kinases
3) Hyaluronidase
4) Collagenase
5) IgA proteases
Describe the enzyme coagulases
coagulate fibrinogen
helps with formation of clot. so when infection bacteria form a blood clot,form a wall, and prevent bloodflow to infection site so immune system cells can’t get to site
ex. staphylococcus
Describe kinases as a way to penetrate host defenses
digest fibrin clots
bacteria will destroy the clotthat host body creates to defend itself so that infection can spread
ex. streptococcous
Describe hyaluronidase as a way to penetrate host defenses
digests polysaccharides that hold cells together
produced by streptococcus
ex.gasgrene
Describe collagenase as a enzyme to penetrate host defenses
breaks down collagen
Describe IgA proteases as a way to penetrate host defenses
destroy IgA antibodies