Toxins L3 Flashcards
What do toxins do?
Directly damage the host in specific ways
What is the purpose of toxins? (3)
- Obtain cell associated nutrients
- Facilitate dissemination (spreading)
- Interfere witt host defenses
What are the tasks of pathogenic bacteria? (4)
- Encounter and enter the host
- Establish an infectious niche
- Multiply and cause damage
- Spread to other tissues, hosts or both
What are the factors responsible for pathogenecity? (4)
- Colonization factors
- Survival factors
- Factors that cause damage or spread
- Regulatory factors
Define TOXIN
Protein that damages eukaryotic cells
What is an exotoxin?
Classical toxin –> secreted by bacteria
What is an endotoxin?
Non proteinaceous lipopolysaccharide of gram - bacteria (potent)
What is Botulism?
- Obligate anaerobe (cannot grow in presence of O2)
- Gram + spore forming bacillus
What does botulism cause?
Flaccid Paralysis
Is Botulism an intoxication or infection?
Intoxication: does not grow in you
What are the two mechanisms of action of Botulinum toxin?
- A toxin
2. B toxin
Describe the A toxin
- Enzymatically Active
- Translocated by the B domain
- Protease that prevents Ach to be released
- Cleaves proteins involved in synaptic vescicle fusion
Describe the B toxin
- Cell Binding
- Recognizes target cells
- RME
- Acidification=membrane insertion
What is Tetanus?
- Spore forming olbigate anaerobe
- Gram +
- Bacillus
What does tetanus cause?
Causes spastic (NOT FLACCID) paralysis
How does tetanus function?
Enter a wound, germinate and produce toxin
How is tetanus similar to botulinum?
Poisons NT release by cleavage of proteins involved in vescicle fusion
Describe FLACCID paralysis
- Botulinum toxins –> translocated to PERIPHERAL NERVES
- Prevent release of STIMULATORY NT like Ach
- Muscles cannot be stimulated to contract (at neuromuscular junctions [NMJ])
Describe SPASTIC paralysis
- Tetanus toxin is translocated at CNS
- Prevents release of INHIBITORY NT like GABA
- Cannot TURN OFF contraction of muscle
What is cholera?
- Gram negative
- Comma shaped
- Faculatative anaerobe (can be in presence or absense of O2)
How does one acquire cholera?
Contaminated food or water
What does cholera cause?
Large volume of watery diarrhea (can be fatal)
What does the cholera toxin target?
G protein that controls [cAMP]
What happens when cholera toxin is involved with its target?
Decrease in Na absorption
Decrease in water uptake
Increase in Cl- secretion
Losing a lot of water in body
