FA Bugs with Exotoxins II Flashcards
MOA diphtheria toxin and exotoxin A
Inactivate EF-2
MOA ST and SLT
INactivate 60 S ribosome by removing adenine from rRNA
MOA ETEC heat-labile toxin (LT)
overactivates adenylate cyclase –> increased cAMP –> increased chloride secretion in gut and H2O effluxu
MOA ETEC heat-stabile toxin (ST)
Overactivates guanylate cyclase –> increased cGMP –> decreased respiration of NaCl and H2O in gut
What is the net effect of both heat-labile and heat-stabile toxin on the infected individual?
Watery diarrhea:
Labile in the Air (adenylate cyclase)
Stable on the Ground (guanylate cyclase)
MOA Edema factor
mimics the adenylate cyclase enzyme –> inc. cAMP
Edematous borders of black eschar
ANTHRAX
Manifestation of edema factor
likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax
Voluminous “rice-water” diarrhea
Cholera
MOA cholera toxin
Over activates adenylate cyclase (–> inc cAMP) by permanently activating Gs –> increased Cl- secretion in gut and H2O efflux
MOA pertussi toxin
Overactivates adenylate cyclase (inc cAMP) by disabling Gi, impairing phagocytosis to permit survival of microbe
Whooping cough bug
Bordetella pertussi
Describe a whooping cough
Child coughs on expiration and whoops on inspiration; can cause 100-day cough in adults
MOA tetanospamis and botulinum toxin
Cleave SNARE protein required for NT release
Muscle rigidity and lock jaw
Tetanus
Flaccid paralysis, floppy baby
Botulism
What neurotransmitters are affected in tetanus?
toxin prevents release of INHIBITORY (GABA and glycine) NTs in spinal cord
What neurotransmitters are affected in botulism?
Toxin prevents release of stimulatory (ACh) signals at NMJ –> flaccid paralysis
MOA alpha toxin
Phospholipase that degrades tissue and cell membranes
MOA streptolysin O
protein that degrades cell membrane
MOA TSST-1 and exotoxin A (as superantigens)
Bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-gamma and IL-2 –> shock
What does alpha toxin do to the patient?
Degradation of phospholipid C –> myonecrosis (“gas gangrene”) and hemolysis (“double zone” of hemolysis on blood agar)
What does streptolysin O do to the patient?
Lyses RBCs; contributes to beta hemolysis;
How do you diagnosed rheumatic fever
Host antibodies against streptolysin O (ASO)
TSST-1 effect on patient
Toxic shock syndrome: fever, rash, shock
Staph aureus exfoliative toxin effect on patient
Scalded skin syndrome
Staph aureus enterotoxin effect on patient
food poisoning
Strep pyogenes exotoxin A effect on patient
Toxic shock syndrome: fever, rash, shock
