Toxic (Bugs w/ exotoxins) Flashcards
Diptheria toxin
Corynebacterium diphtheria
Inactivates elongation factor 2
Pharyngitis & pseudomembrane in throat
Exotoxin A
Pseudomonas aeruginosa
Inactivates elongation factor 2
Host cell death
Shiga toxin
Shigella
Inactivates 60S ribosome by cleaving rRNA
GI mucosal damage –> dystentery
Enhances cytokine release, causing HUS
Shiga-like toxin
EHEC (including 0157:H7 strain)
Inactivate 60S ribosome by cleaving rRNA
Enhances cytokine release, causing HUS; unlike shigella, EHEC does NOT invade host cells
Heat-labile toxin
ETEC
Overactivats adenylate cyclase –> elevated cAMP –> elevated chloride secretion in gut + H2O efflux
Watery diarrhea
Labile in the air, stable on the ground
Heat stable toxin
ETEC, Yersinia enterocolitica
Overactivates guanylate cyclase (increases cGMP) leading to reabsorption of NaCL & H2O in gut
S/S ETEC: Watery diarrhea
S/S Yersinia: Bloody diarrhea
Edema factor
Bacillus anthracis
Minimizes adenylate cyclase enzyme (increasing cAMP)
Likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax
Cholera toxin
Vibrio cholerae
Overactivats adenylate cyclase (increases cAMP) by permanently activating Gs –> increased Cl- secretion in gut and H2O efflux
Voluminous “rice water” diarrhea
Pertussis toxin
Bordetella pertussis
Overactivates adenylate cyclase (increases cAMP) by disabling Gi, impairing phafocytosis to permit survival of microbe
Whooping cough: child coughs on expiration and “whoops” on inspiration
Tetanospasmin
Clostridium tetani
Cleaves SNARE protein required for neurotransmitter release
Muscle rigidity and ‘lock jaw’
Toxin prevents release of inhibitory (GABA & glycine) neurotransmitters in spinal cord
Botulinum toxin
Clostridium botulinum
Cleave SNARE protein required for neurotransmitter release
Flaccid paralysis, floppy baby; toxin prevents release of stimulatory (Ach) signals at MSK junction –> flaccid paralysis
Alpha toxin
Clostridium perfringens
Phospholipase that degrades tissue, cell membrane
Degradation of phospholipids –> myonecrosis (gas gangrene) and hemolysis (double zone of hemolysis on blood agar)
Streptolysin O
Streptococcus pyogenes
Protein that degrades cell membrane
Lyses RBCs; contributes to beta-hemolysis; host antibodies against toxin (ASO) used to diagnose rueumatic fever
Exotoxin A
Streptococcus pyogenes
Bring MHC II & TCR in proximity to cause overwhelming release of IFN-gamma and IL-2, causing shock
Causes Toxic shock syndrome: fever, rash, shock
TSST
Toxic shock syndrome toxin- staph aureus
Bring MHC II & TCR in proximity to cause overwhelming release of IFN-gamma & IL-2 –> shock
TSS: fever, rash, shock
Other toxins cause scalded skin syndrome (exfoliative toxin) & food poisoning (enterotoxin)
