Toxic (Bugs w/ exotoxins) Flashcards Preview

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Flashcards in Toxic (Bugs w/ exotoxins) Deck (15):
1

Diptheria toxin

Corynebacterium diphtheria

Inactivates elongation factor 2

Pharyngitis & pseudomembrane in throat

2

Exotoxin A

Pseudomonas aeruginosa

Inactivates elongation factor 2

Host cell death

3

Shiga toxin

Shigella

Inactivates 60S ribosome by cleaving rRNA

GI mucosal damage --> dystentery
Enhances cytokine release, causing HUS

4

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

5

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

6

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

7

Edema factor

Bacillus anthracis

Minimizes adenylate cyclase enzyme (increasing cAMP)

Likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax

8

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

9

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

10

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

11

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

12

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)

13

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

14

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

15

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)