Toxins

Question 1

Corynebacterium diphtheriae

Answer 1

Diphtheria toxin (A-B toxin), inactivates elongation factor (EF-2) -> inhibits protein synthesis
Pharyngitis and pseudomembrane in throat
Lysogenic

Question 2

Pseudomonas aeruginosa

Answer 2

Exotoxin A (A-B toxin), inactivates elongation factor (EF-2) -> Inhibits protein synthesis
Host cell death

Obligate Aerobe
Produces Blue-Green pigment

Question 3

Shigella spp.

Answer 3

Shiga toxin ST, inactivates 60S ribosome by cleaving rRNA -> inhibits protein synthesis
GI mucosal damage -> dysentery
Enhances cytokine release -> HUS

Question 4

Enterohemorrhagic E. coli (EHEC)

including O157:H7 strain

Answer 4

Shiga-like toxin SLT, inactivates 60S ribosome by cleaving rRNA -> inhibits protein synthesis
Enhances cytokine release - > HUS
(does not invade host cells)
Lysogenic

Question 5

Enterotoxigenic E. coli (ETEC)

Answer 5

Heat-Labile exotoxin (LT) (A-B toxin), overactivates adenylate cyclase (incr. cAMP) -> incr. Cl- secr in gut and H20 efflux (incr. fluid secr)
Watery Diarrhea

Heat-Stable toxin(ST), overactivates guanylate cyclas (incr. cGMP) -> decr reabsorption of NaCl and H20 in gut
Watery Diarrhea

“Labile in the Air, Stable on the Ground”

Question 6

Yersinia enterocolitica

Answer 6

similar to the ETEC Heat-Stable toxin (ST)
invades and destroys cells -> dysentery
Blood Diarrhea

Question 7

Bacillus anthracis

Answer 7

Edema Factor, mimics the adenylate cyclase enzyme (incr cAMP)
Lethal Factor
Cutaneous anthrax -> Black eschar (painless)
Pulmonary anthrax from inhalation of spores (flulike symptoms that progress to fever, pulm hemorrhage, medistinitis, and shock) - Woolsorter’s Dz

Question 8

Vibrio cholerae

Answer 8

Cholera toxin (A-B toxin), overactives adenylate cyclase (incr cAMP) by permanently activating Gs -> incr Cl- secr in gut and H20 efflux
Voluminous “rice-water” diarrhea
Lysogenic

Question 9

Bordetella pertussis

Answer 9

Pertussis toxin (A-B toxin), overactivates adenylate cyclase (incr cAMP) by disabling Gi, inhibiting phagocytosis to permit survival of microbe
Whooping Cough (cough on exp, whoop on insp)

Question 10

Clostridium tetani

Answer 10

Tetanospasmin toxin, cleaves SNARE protein required for neurotransmitter release & prevents rel of inhibitory (GABA and glycine) NTs in spinal cord
Muscle rigidity, lock jaw (trismus), risus sardonicus

Question 11

Clostridium botulinum

Answer 11

Botulinum toxin, cleaves SNARE protein required for NT rel & prevents rel of stimulatory (Ach) signals at the NMJ
Flaccid Paralysis, Floppy Baby (ingestion of spores in honey)
Lysogenic

Question 12

Clostridium perfringens

Answer 12

Alpha toxin, (lecithinase) phospholipase that degrades tissue, cell membranes
Myonecrosis (gas gangrene)
Hemolysis (double zone of hemolysis on blood agar)

Question 13

Streptococcus pyogenes

Answer 13

Streptolysin O, protein that degrades cell membrane
Lysis RBCs, contributes to Beta-hemolysis
Host Abs against toxin (ASO) used to dx Rheumatic Fever

Exotoxin A, bring MHC II and TCR in proximity to cause overwhelming rel of IFN-gamma and IL-2
Toxic Shock Syndrome - Fever, Rash, Shock
Lysogenic

Question 14

Staphylococcus aureus

Answer 14

Toxic Shock Syndrome toxin (TSST-1), bring MHC II and TCR in proximity to cause overwhelming rel of IFN-gamma and IL-2
Toxic Shock Syndrome - Fever, Rash, Shock

Efoliative toxin -> scalded skin syn
Enterotoxin -> food poisoning

Question 15

Endotoxin

Answer 15

A lipopolysaccharide found in the outer membrane of Gram - bacteria
Heat-Stable

Question 16

5 Bacterial toxins encoded in a lysogenic phage

Answer 16

ABCDE
shigA-like toxin
Botulinum toxin
Cholera toxin
Diptheria toxin
Erythrogenic toxin of strep pyogenes

Question 17

Clostridium difficile

Answer 17

Toxin A (enterotoxin) binds brush border of the gut
Toxin B (cytotoxin) destroys the cytoskeletal structure of enterocytes causing pseudomembranous colitis.
Often secondary to antibiotic use (clindamycin, ampicillin)
Dx by one or both toxins in the stool
Tx - oral Vancomycin or Metronidazole