Final Flashcards
How does a capsule protect a pathogen?
- Prevents PAMP-PRR interactions
- if it has sialic acid it can bind to serum protein H and degrade opsonin C3b
- some prevent formation of C3 convertase
Capsules with silica acid do what?
bind to serum protein H which leads to degradation of opsonin C3b
How does the host fight a capsule?
produce opsonizing antibodies specifically against the capsule
Streptococcus progenies evades complement how?
M protein binds serum factor H which degrades C3b
How do pathogens get around antimicrobial peptides?
- charge repulsion
- peptidases
- reduced uptake of peptides because of capsule
- efflux pumps
- biofilm
virulence factors enable bacteria to do what?
- attach and colonize
- invade and disseminate
- evade host immune system
- eat and grow
- spread
How can you evade the adaptive immune system?
- antigenic variation
- molecular mimicry
- IgA proteases
- protein A, protein G
- biofilm
How does Neisseria use antigenic variation to escape antibodies?
pili as adhesins and different subsets of pili
How do flu viruses use antigenic variation to escape antibodies?
- mutations and seasonal variations of flu strains
- antigenic drift
- antigenic shift
molecularly mimicry example
streptococcus capsule is made of hyaluronic acid which is commonly found in the body
Which proteins does streptococcus produce?
proteins A and G
What do proteins A and G do?
bind to Fc region of antibodies (instead of epitopes)
How can pathogens avoid cytotoxic T cells?
- kill them
- interfer with MHC
pseudomonas classification
- aerobic
- Gram -
- metabolically diverse
- saprophytes (feed on decaying organisms)
is pseudomonas motile?
yes it has polar flagella
Why do some strains of pseudomonas appear mucoid?
polysaccharide alginate
what does pseudomonas smell like?
grapey
what color is pseudomonas and why?
blue green pigment pyocyanin
p aeruginosa is what type of infection?
opportunistic and often nosocomial
How does p aeruginosa spread?
environment (NOT patient to patient)
How does p aeruginosa attach?
pilus and non-plus adhesins
What type of motility does p aeruginosa have?
- swimming
- swarming
- twitching
What enzymes does p aeruginosa make?
- toxins
- proteases
- DNAases
what type of pili does p aeruginosa use to attach to host cells?
type 4
What type of toxins does p aeruginosa secrete?
type 3
What does staphylococcus aureus look like?
a bunch of golden grapes
Staphylococcus classification
- gram +
- non-motile
- non-spore forming
- facultative anaerobe
staphylococcus aureus is what type of pathogen?
commensal and nosocomial
How does MRSA do?
change penicillin binding protein (PBP)
How do vancomycin do?
inhibits cell wall synthesis by binding to hanging chain of peptidoglycan
How do VRSA do?
modify binding site and replace with low-affinity precursors
what are the staphylococcus aureus adhesins
fibrinogen, fibronectin binding surface proteins Fnbp A and B, ClfA and B, IsdA, and WTA
how does staphylococcus aureus inhibit phagocytosis
- capsule
- proteins A and G which bind to Fc region of IgG antibodies and avoid opsonization
how does staphylococcus aureus inhibit neutrophil migration
- inhibitory protein (CHIPS) binds to and inhibit chemotactic receptors
extracellular adherence protein (Eap) decreases ICAM-1 expression on endothelial cells
How does staphylococci aureus inactivate reactive oxygen species?
- golden carotenoid pigment
- superoxide dismutase (SOD)