virulence factors
•Streptococcus pneumoniae produces____
IgA protease
Grow intracellularly •Escape the phagosome:
ListeriaandRickettsia.
-S. pyogenes produces ___ to Prevent phagocytosis
M protein
Diphtheria toxin: mode of action
Same as P. aeruginosa (pseudomonas) Exotoxin A ADP-ribosyl transferase Inactivates elongation factor 2 Inhibits host protein synthesis
-S. pneumoniae, H. influenzae, and K. pneumoniae, produce a ___ to Prevent phagocytosis
capsule
Exotoxins Preformed toxins:
food poisoning, ex. S. aureus
Exotoxins Hemolysins
•: break down red blood cells -Example: Streptococcus pyogenes (Beta) •Strep and staph aureous is Beta hemolytic
Clostridium tetani
•Blocks the release of inhibitory neurotransmitters (glycine and GABA) across the synaptic cleft. •Constant stimulation by acetylcholine, resulting in spastic paralysis.
Clostridium botulinum
•Botulinum toxin binds to presynaptic nerve terminal •Receptor binding is irreversible -Prevents presynaptic acetylcholine release -Results in FLACCID paralysis and skeletal muscle weakness
Endotoxin:
•Lipopolysaccharide, LPS -Attached to bacterial cell (All gram negativerods)
Endotoxin
•Only in Gram negative bacteria •Growing cells continually release cells small amounts of LPS.
Staphylococcus aureus produce ___
•coagulase •Coagulates fibrinogen forming abscesses
Exotoxins Cytotoxins
•destroy host cells -Example: Clostridium perfringens phospholipase C •
Pseudomonas produces ___
•elastase -Breaks down elastin in skin and connective tissue -
Streptococcus produces ___
•hyaluronidase -Breaks down the hyaluronic acid
Exotoxins Neurotoxins
•interfere with neural transmission Example:Clostridium tetanitetanus toxin
Grow intracellularly •Prevent phagosome/lysosome fusion:
- Mycobacterium
Antigenic variation:
- Neisseria gonorrhoeae
Exotoxins •Enterotoxins
-Example: Vibrio cholerae cholera toxin •GI tract ie. Vomiting diarrhea
Grow intracellularly •Break down H2O2:
-Staphylococci produce catalase
Siderophores
-lactoferrin, transferrin, ferritin, or hemin
•Streptococcus pyogenes:
C5a protease
•LPS binds to __ and ___ on monocytes and macrophages
CD14 and toll like receptor 4 (TLR4) on monocytes and macrophages -Induces IL-1 and TNFα production
Phospholipases
Clostridium perfringens phospholipase
Superantigen :Gram positive cocci Streptococcus pyogenes: Streptococcal pyrogenic exotoxin A
Streptococcal pyrogenic exotoxin A
Pore-forming exotoxin
Streptococcus pyogenes Streptolysin O-creates a pore and destroys cell
Superantigen :Gram positive cocci Staphylococcus aureus:
TSST 1
Cholera toxin
irreversibly activates the Gs regulatory protein ¯ activates adenylate cyclase ¯ causing cAMP concentration to rise ¯ triggering the cell to pump Cl- and water into the intestinal lumen ¯ causing diarrhea
-Staphylococcus & Streptococcus produce ___ to destroy leukocytes and macrophages
leukocidins
