Usmle Step One 2011 Exotoxins

Front 1

Superantigens

Back 1

bind directly to MHC II and T-cell receptor simultaneously, activating large numbers of T cells to stimulate release of IFN-gamma and I-2

Front 2

S. aureus

Back 2

TSST-1 superantigen causes toxic shock syndrome

Front 3

S. pyogenes

Back 3

Scarlet fever-erythrogenic toxin causes toxic shock-like syndrome

Front 4

ADP ribosylating A-B toxins

Back 4

interfere with host cells function. B component binds to a receptor on surface of host cell, enabling endocytosis. A component then attaches an ADP-ribosyl to a host cells protein, altering protein function

Front 5

C. diphtheriae

Back 5

Inactivates elongation factor (EF-2) casuses pharyngitis and pseudomembrane in throat. NEVER SCRAPE!

Front 6

V. cholerae

Back 6

ADP ribosylation of G protein stimulates adenylyl cyclase, increases the pumping of Cl into gut and decreases sodium absorption. H20 moves into gut lumen, causing voluminous rice-water diarrhea

Front 7

E. coli

Back 7

Heat labile toxin stim adenylate cyclase. head stable toxin stimulates guanylate cyclase. both cause watery diarrhea.

Front 8

B. pertussis

Back 8

Increases cAMP by inhibiting Gaphai, causes whooping cough, inhibits chemokine receptor, causing lymphocytosis

Front 9

C. perfringes

Back 9

alpha toxin, causes gas grene

Front 10

C. tetani

Back 10

blocks the release of GABA and glycine, causes "lockjaw"

Front 11

C. botulism

Back 11

blocks the release of Ach, causing anticholinergic symptoms, CNS paralysis, especially cranial nerves

Front 12

B. anthracis

Back 12

edema factor, part of toxin complex is an adenylate cyclase increasing cAMP

Front 13

Shigella

Back 13

Shiga toxin (also produced by E.coli O157:H7) cleaves host cell rRNA, enhances cytokine release, causing HUS

Front 14

S. pyogenes

Back 14

Streptolysin O is a hemolysin, antigen for ASO antibody which is the Dx for rheumatic fever

Front 15

cAMP inducers

Back 15

V. cholerae toxin
Pertusiss toxin
E. coli heat labile toxin (ETEC)
B. anthracis toxin

cholera, ecoli, and pertussis active adenylate cyclase to increase cAMP, while pertussis is an adenylate cyclase to increase cAMP