IA. General microbiology | 15. Toxic virulence factors of bacteria

Question 1

What are the 2 types of bacterial toxins?

Answer 1

exotoxins and endotoxins

Question 2

I. Exotoxins
1. How are Exotoxins produced and secreted?

Answer 2

1. Produced by bacteria (either gram + or -, but mostly +)
   - Usually specific to a particular bacterial species and functions as a virulence factor
   - Some bacteria only use their exotoxins for virulence
2. Secreted by the bacteria and travel to the target organ through the blood

Question 3

I. Exotoxins
2. What is the degree of illness can exotoxins give?

Answer 3

Severe, special symptoms

Question 4

I. Exotoxins
3. What can Exotoxins be attenuated to?

Answer 4

Can be attenuated to TOXOID (vaccination!)
- Toxoid is a toxin that has lost its toxic properties, but kept its antigenic

Question 5

I. Exotoxins
4. What are the 5 subdivisions of exotoxins?

Answer 5

Some can be subdivided into categories indicating location of action
- Neurotoxin
- Enterotoxin
- Leukocidin
- Hemolysin
- Cytotoxin
- Lethal toxin

Question 6

I. Exotoxins
5A. What are the effects of exotoxins?

Answer 6

1. Cytolytic effect
2. Inhibition of protein synthesis
3. Hypersecretion of ions
4. Neurotoxin
5. Superantigens

Question 7

I. Exotoxins
5B. One of the Effects of Exotoxins is Cytolytic effecT
=> Explain and give examples

Answer 7

a. Pore formation on the membrane that can directly lyse and kill host cells
b. E.g. a-toxin of C. perfringens

Question 8

I. Exotoxins
5C. One of the Effects of Exotoxins is Inhibition of protein synthesis
=> give examples

Answer 8

E.g. diphtheria toxin

Question 9

I. Exotoxins
5C. One of the Effects of Exotoxins is Hypersecretion of ions
=> give example(s)

Answer 9

a. E.g. cholera toxin

Question 10

I. Exotoxins
5D. One of the Effects of Exotoxins is Neurotoxin
=> give example(s)

Answer 10

a. E.g. botulinum toxin, tetanus toxin

Question 11

I. Exotoxins
5D. One of the Effects of Exotoxins is Neurotoxin
=> give example(s)

Answer 11

a. E.g. botulinum toxin, tetanus toxin

Question 12

I. Exotoxins
5E. One of the Effects of Exotoxins is Superantigens
=> give example(s)

Answer 12

a. Superantigens can activate many T cells → cytokine storm → life threatening immune response
b. E.g. toxic shock syndrome toxin (S. aureus) and erythrogenic toxin (S.pyogenes)

Question 13

II. Endotoxin
1. What is the definition of endotoxin?

Answer 13

Lipopolysaccharides (LPS) associated with the cell walls of gram NEGATIVE bacteria

Question 14

II. Endotoxin
2. What are the features of endotoxin?

Answer 14

• Part of Gram NEGATIVE bacteria
• Released at cell death
• General symptoms: fever, hypotension
• Very resistant to heat and enzymes
• Lipid (poor antigen)
• Cannot be attenuated