Microbial toxins and mycotoxins Flashcards Preview

Vet - notes > Microbial toxins and mycotoxins > Flashcards

Flashcards in Microbial toxins and mycotoxins Deck (12):
1

Endotoxin

LPS - specifically Lipid A
Causes release of cytokines

2

Endotoxin - clinical signs

fever, hypotension, loss of effective circulation

3

types of Exotoxins

bacterial proteins
Cytolytic toxins
Enzymes
Enterotoxins
Neurotoxins
Superantigens
ADP-ribosylation toxins
Type III secretion systems
Clostridial toxins - botulinum toxin

4

Cytolytic toxin - examples

Sometimes haemolysins - Streptolysin S of Strep equi
Sometimes not haemolytic, but still damage cells - leukocidins, ApxIII of Actinobacillus pleuropneumoniae

5

Enzymes - examples

Phospholipase C of Clostridium perfringens = alpha toxin
hyaluronidase, collagenase, protease, lipase

6

LT (labile toxin)

Similar to Cholera toxin.
Attaches to brush border of small intestinal cells
activates Cl channel - Na + water follow Cl out of cell

7

Neurotoxins

Botulinum toxin - blocks release of acetylcholine
at the synapse and neuromuscular junction.
Flaccid paralysis and death.

8

Tetanus toxin

Blocks release of neurotransmitters for inhibitory synapses - uncontrolled excitatory synaptic activity.
Paralysis by constant tensing of muscles - tetani.

9

Superantigens

Staphylococcus aureus TSST-1 protein.
Immunomodulators - induce massive T-cell activation &
cytokine release.
Toxin binds to invariable regions on MHC Class II on APC;
the normal process of T-cell activation is short-circuited.

10

Mycotoxins

Toadstool poisoning
Ingestion of plant pathogenic fungi (Ergotism)
Ingestion of moulded feed (Mycotoxicosis)

11

Ergotism or ergot poisoning

Sclerotium forms in grass & cereal

12

Ergotism or ergot poisoning - clinical effect

contain vasoactive alkaloids
constriction of arterioles in extremities → gangrene &
lameness. Also convulsions.
Halucinations & pain in humans