virulence Flashcards
which virulence factorr is key for staph aures ?
protein A
how does protein A work ?
inhibits phagocytosis by binding the Fc portion prevents the activation of the immune system and no opsonization happens and no compliment is activated
what bacteria are associated with the IgA protease cleavage factor ?
SHiN
s pneumonia
haemophilus influenza b
neisseria
how does IgA proteas works ?
cleavage of gA allows for thee invasion of mucosal surfaces
what bacteria uses thee M protein as a virulence factor ?
group A strep
associated with rheumatic fever
due too molecular mimicry
what are the post strep complicatons ?
rheumatic heat disease
glomerulonephritis
what determines what post strep complication you get ?
depends on he M protein subtype
strains that cause impetigo will result n GN
strains that cause pharyngitis will cause rheumatic fever
main differences between endo and exotoxins ?
endotoxins are only secreted by gram negative bacteria when they die (LPS)
exotoxins are proteins synthesised by bacteria
what are the feeatures associated with endotoxins ?
all produced by gram negative bacteria
all have a lipid a core
O antigen
how do endotoxin present as illness?
they allow for the release of IL 2 and TNF
why cant we make vaccines against endotoxins ?
weak antibody response
what are the immune responses associated with LPS ?
macrrophage - IL 1 , TNF and nitrric ooxide
complement - C3a releasee , C5a relas
tissuee factor - coagluation and DC
what is thee endotoxin receptor ?
CD14
what are the different mechanisms associated with exotoxins ?
inhibition of protein synthesis
increase fluid secretion
inhibit phagocytic ability
inhibit release of neurotransmitters
which bacteria are associated with exotoxins that inhibit protein synthesis ?
diphtheria
pseudomonas
shigella
enterohaemorrrhagic E coli
what are the toxins associated with diphtheria and pseudomonas and what is their mechanism of action ?
diphtheria toxin
exotoxin A
both allow for the ADP ribosylation off EE2F elongation factor
what is the toxin associated with shigella and what is thee mechanism of action ?
shiga toxin binds to the 60 S subunit off ribosomes
shiglla invadess thee host cell
what is the presentation off diphtheria ?
membranous lymphadenopathy
bulls neck
what is the presentation of shigella infection ?
infectious diarrhea
what s thee virulence factor associated with E E.coli ?
shiga like toxin
also binds to 60 S portion of ribosomes
causes bloody diarrhea
what are the two classic examples associated with systemic reactions to endotoxins ?
meningococcemia
gram negative sepsis
what is the man mechanisms of disease n shigella vs in E.Ecoli?
shigella - invasion of inteestiinal cells
e.col - through toxn releasee
what happens upon the release of shiga toxin into the blood ?
hemolytic uremic syndrome
only associated with E E coli
what are the bacteria that release exotoxins that. increase fluid secretion ?
entrotoxigenic e coli
bacillus anthrax
cholera
how do clls in the GI tract secrete fluids ?
the more chlorine out
the more water in
what is the chlorine controlled by in the GI tract ?
CFTR gene
what must bee done to increase chlorine secretion ?
activate Gs or AC
what are the toxins associated with enterotoxigenic e coli ?
heat labile exotoxin - activate cAMP
heat stable exotoxin- activates cGMP
what are the three proteins associated with bacillus anthrax ?
protective antigen
lethal factoor
edema factor
what is the edma toxin compromised of ?
PA + EF
what. does edema toxin mimic ?
adenyl cyclase
what is the presentation of anthrax ?
lung affection - necrotizing pneumonia
skin affection - black escharin
GI - ulcers
what is thee toxin associated with cholera ?
cholera toxin
overactivates cAMP
Gs is always active
what are the bacteria that inhibit phagocytosis ?
bordatella pertussis
pertussis toxin G inhibitory protein inactivation so over activation of adenylate cyclase
which bacteria are associated with the inhibition of neurotransmitters and the associated toxins ?
clostridium tetani - tetanospasmin
clostridium botulinum -botlinium toxin
what is the mechanism of action associated with the toxins from bacteria that inhibt neurotransmitters ?
tetanospasmin - rigid paralysis
botulinim - flaccid paralysis
what type of cells does tetanospasm work on ?
reenshaw cells
what bacteria release exotoxins associated with the lysis of cell membrane and what are the toxins associated ?
clostridium perferengens - alpha toxin
strep pyogens - streptolysin O
what is the mechanism of action off alpha toxin ?
phospholipase that degrades tissue and cell membranes
causes myonecrosis gas gangrene
what is the mechanism off action of streptolysin O ?
protein that degrades cell memb
what is seen on blood agar with strep pyogens ?
double zone of hemolysis
what are the toxoid vaccines ?
DTaP
diphtheria and tetanus and acellular pertussis
what are superantigens ?
a type of exotoxin that causes a huge recruitment of T cells
hue release of IL 2 and IFN gamma
what are the 2 bacteria associated with superantigens ?
staph aureus TSST 1
strep pyogens A or C
what clinical scenarios are associated with TSS ?
staph and packing
women with tampon
surgical wound with packing
how can TSS seperated from sepsis ?
TSS , resemble a sunburn with desquamation of the hand ad the soles
diarrhea is also common in TSS but not in sepsis
what is staph TSS commonly associated with ?
strep TSS
