Exotoxins

Front 1

S. aureus

Back 1

1. TSST-1 superantigen
2. Enterotoxin (food poisoning)
3. Exfoliatin: staph scalded skin syndrome

Front 2

S. pyogenes

Back 2

1. Superantigen: Scarlet fever-erythrogenic toxin: toxic shock-like syndrome
2. Streptolysin O (a hemolysin antigen): an ASO antibody, which is used in the dx of rheumatic fever

Front 3

C. diphtheriae

Back 3

ADP ribosylating A-B toxin:
Inactivates EF-2: inhibits protein synthesis --> pseudomembranous pharyngitis

*inhibits protein synthesis --> cell death

Front 4

V. cholerae

Back 4

ADP ribosylating A-B toxin:
Ribosylation permanently activates Gs --> stimulates adenylate cyclase --> increased cAMP -->pump Cl- into gut

Front 5

E. coli

Back 5

ADP ribosylating A-B toxin:
Heat-labile toxin: stimulates Adenylate cyclase --> increased cAMP
Heat-stable toxin: stimulates Guanylate cyclase

both cause watery diarrhea

Front 6

Bordetella pertussis

Back 6

Toxin permanently disables Gi --> increases cAMP --> whooping cough

Inhibits chemokine receptor, causing lymphocytosis, pmn and lymphocyte dysfunction, histamine sensitivity, increased insulin

Front 7

Bacillus anthracis

Back 7

Toxin complex includes:
1. Lethal Factor
2. Edema factor = bacterial adenylate cyclase --> increased cAMP
3. Protective antigen

Another virulence factor:
Anti-phagocytic poly-gamma-D-glutamic acid capsule

Front 8

Clostridium perfringens

Back 8

alpha toxin = lecithinase
Acts as a phospholipase to cleave cell membranes and cause gas gangrene

Get double zone of hemolysis on blood agar

Front 9

C. tetani

Back 9

Tetanospasmin: Blocks the release of GABA and glycine (inhibitory neurotransmitters)

Front 10

C. botulinum

Back 10

Heat-labile toxin: blocks release of ACh at neuromuscular junction --> anticholinergic sxs, CNS paralysis

Front 11

Shigella

Back 11

Shiga toxin (also produced by E. coli O157:H7): cleaves host cell rRNA, inactivating 60S ribosome

enhances cytokine release, causing HUS

Front 12

Protein A virulence factor

Back 12

S. aureus
Binds Fc region of Ig to prevent opsonization and phagocytosis (prevent complement fixation)

Front 13

IgA protease virulence factor

Back 13

Secreted by encapsulated organisms: S. pneumo, HiB, Neisseria

Cleaves IgA dimer in order to colonize respiratory mucosa

Front 14

M Protein virulence factor

Back 14

Group A Strep

Helps prevent phagocytosis

Front 15

C. diff

Back 15

Toxin A: enterotoxin that binds to brush border of gut; it is a pmn chemoattractant
Toxin B: cytotoxin destroys the cytoskeletal structure of enterocytes (via actin depolymerization), causing pseudomembranous colitis

Front 16

Neisseria Meningitidis virulence factor

Back 16

Lipooligosaccharide (like LPS of GNRs); this outermembrane acts as an endotoxin; associated with disease manifestations and severity of disease

Front 17

Superantigens

Back 17

Bind directly to MHC II and TCR simultaneously --> activate large numbers of T cells to stimulate release of IFN-gamma (macs) and IL-2 (T cells)

ex: TSST-1, scarlet fever-erythrogenic toxin

Front 18

ADP ribosylating A-B toxins

Back 18

Interfere with host cell function
B: BINDING to receptor on surface of host cell, enabling endocytosis
A: ACTIVE component attaches an ADP-ribosyl to a host cell protein, altering protein function

BCDE:
Bordetella
Cholera
Diphtheria
E. coli

Front 19

cAMP inducers

Back 19

Same as ADP ribosylators (except Anthrax instead of Diphtheria)

Bordetella
Cholera
Bacillus anthracis (EF)
E. coli (heat-labile toxin)

Anthrax is itself an adenylate cyclase
*the other 3 use ADP ribosylation to permanently activate endogenous adenylate cyclase

Cholera stimulates Gs
Pertussis inhibits Gi; also promotes lymphocytosis by inhibiting chemokine receptors

Front 20

Endotoxin

Back 20

lipopolysaccharide in outer membrane of:
GRAM-NEG bacteria
& LISTERIA!!

Neg for Ndotoxin
*heat stable

Lipid A induces IL-1 and TNF

MAC COMPuter FACTORy
Activates macrophages:
IL-1: fever
TNF: fever, hemorrhagic necrosis
NO: hypotension

Activates complement (alternative):
C3a: hypotension; histamine
C5a: PMN chemotaxis

Activates Hageman factor (12):
coag cascade --> DIC