Bacterial Neurotoxins Flashcards
What causes botulism, tetanus, and gas gangrene?
Clostridia
Clostridia- catalase, anaerobes, gram
+or -?
Gram +
Catalase -
Strict Anaerobic
Why can’t Clostridia break down h2o2?
They are catalase -
What happens when Clostridia is in presence of 02?
Toxic superoxide anions accumulate– they lack the enzyme superoxide dismutase
And are strict anaerobes
Can clostridium use oxygen as final e acceptor?
NO
Paralytic illness die to neurotoxins made by c botulinum
Botulism
Food
Wound
Infant floppy baby syndrome
Which type of botulism has preformed toxin and which is the toxin made in vivo?
Infant made in vivo and food poisoning is preformed toxin
Most common botulinum toxin forms
A b and e
Can c botulinum be killed w heat?
Spores are heat resistant
Mode of action for c botulinum?
Interferes w release of ach at neuromuscular junction results in flaccid paralysis
BoNT
C botulinum
C botulinum is what kind of enzyme?
BoNT is a endoprotease
How does c botulinum interrupt nmj?
The neurotoxin cleaves a price of neuro secretory apparatus like a membrane protein (snare proteins) so seiches can’t release ach
How does good poisoning develop?
C botulinum spores contaminate canned or packed food and germinate in the alkaline pH!
Anaerobic conditions allow vegetative form and toxin is produced
Absorbed by body and toxin is NOT killed by digestive enzymes
Clinical manifestations of food botulism?
Dry mouth, hard to swallow, visual disturbances, speech issues, descending paralysis
But NO FEVER
recovered people don’t have antitoxin in blood
Floppy baby syndrome
Gi Tract colonized from env source (honey?) and toxin produced in vivo
Treatment is BIG-iv - intravenous botulism immune globin –human derived antitoxin antibodies
Deadliest toxin with no known antidote
Botulinum toxin type H
Good uses of Botox
Muscle spasms Migraines Over active bladders Strabismus Cosmetic use
Neurotoxin of tetanus
Tetanospasmin
What makes Tetanospasmin?
Clostridium tetani
Spores of c tetani is found in
Feces and soil
Clinical symptoms of tetanus
Trismus (lockjaw) Risus sardonicus(sustained grin) Stiff neck Hard to swallow, rigid abdominals Voluntary muscle spasm
C tetani mode of action
Cleaves VAMP(synaptobrevin) And prevents release of neurotransmitter glycine from inhibitory intereurons in spinal cord Leads to stimulation of muscle contractions
How does tetanus get in body?
Puncture wounds or burns
Inside body what happens with c tetani
Spores get in through wound and reverts to vegetative form w help from organisms and necrotic tissue
Toxin spreads in blood and lymph associated w nerves
Toxin combines with gangliosides
Treatment for tetanus?
Antitoxin- doesn’t neutralize toxin already bound to nerve tissue
Immunization
Prevention - TETANUS IMMUNE GLOBIN(tig)
What does metronidazole do
Inhibits c tetani growth
