Lecture 4 Part 1: Clostridium, Bacteroides, and Other Anaerobes

Question 1

How many Clostridium species are prevalent in human disease?

Answer 1

four

Question 2

Name the 4 Clostridium species prevalent in human disease?

Answer 2

1. C. perfringens
2. C. tetani
3. C. botulinum
4. C. difficile

Question 3

Which disease is caused by Clostridium perfringens?

Answer 3

gas gangrene

Question 4

Which disease is caused by Clostridium tetani?

Answer 4

tetanus

Question 5

Which disease is caused by Clostridium botulinum?

Answer 5

botulism

Question 6

Which diseases are caused by Clostridium difficile?

Answer 6

diarrhea and colitis

Question 7

Do all 4 4 Clostridium species prevalent in human disease form spores?

Answer 7

YES, THEY ALL FORM SPORES

Question 8

What are the four general properties of Clostridium species? (on slide it says some exceptions)

Answer 8

1. presence of endospores so it can survive adverse environmental conditions
2. strict anaerobic metabolism
3. inability to reduce sulfate to sulfite
4. Gram(+) cell wall

Question 9

What type of metabolism do Clostridium species have?

Answer 9

strict anaerobic metabolism (they thrive in environments without oxygen)

Question 10

can Clostridium species reduce sulfate to sulfite?

Answer 10

no, they have an inability to reduce sulfate to sulfite

Question 11

Name 4 places where Clostridium species commonly found?

Answer 11

They are ubiquitous in
1. soil
2. water
3. sewage
4. endogenous flora (normal flora of the body)

Question 12

In terms of virulence how does Clostridium induce damage?

Answer 12

through numerous toxins

Question 13

What is the shape and Gram-staining characteristic of Clostridium perfringens?

Answer 13

large, rectangular Gram-positive rods

Question 14

How many types of Clostridium perfringens are there, and what are they based on?

Answer 14

there are 5 types (A-E) based on toxin production.

Question 15

Which type of Clostridium perfringens is most prevalent in human infections?

Answer 15

type A

Question 16

What are the four lethal toxins of Clostridium perfringens?

Answer 16

1. Alpha toxin
2. Beta toxin
3. Epsilon toxin
4. Iota toxin

Question 17

What is the function of Clostridium perfringens Alpha toxin?

Answer 17

It is a phospholipase C that causes hemolysis (destruction of red blood cells)

Question 18

Which Clostridium perfringens toxin is a pore-forming toxin?

Answer 18

beta toxin

Question 19

How is Epsilon toxin activated?

Answer 19

It is a protoxin that is activated by trypsin

Question 20

What is the mechanism of the Iota toxin?

Answer 20

It is an A-B toxin
the B subunit forms pores
the A subunit binds G actin

Question 21

What does Clostridium perfringens enterotoxin do?

Answer 21

It is a heat-labile toxin that causes fluid loss and also acts as a superantigen

Question 22

What types of soft-tissue infections can Clostridium perfringens cause?

Answer 22

soft-tissue infections ranging from cellulitis to gas gangrene

Question 23

What is gas gangrene and how is it caused by Clostridium perfringens?

Answer 23

Gas gangrene is a severe infection where rapidly dividing bacteria produce gas metabolites

Question 24

What type of foodborne illness can Clostridium perfringens cause?

Answer 24

food poisoning

Question 25

What is necrotizing enteritis and how is it related to Clostridium perfringens?

Answer 25

Necrotizing enteritis is a severe intestinal infection caused by Clostridium perfringens

Question 26

What other serious conditions can Clostridium perfringens cause?

Answer 26

Endometritis and septicemia

Question 27

What is the shape and Gram-staining characteristic of Clostridium tetani?

Answer 27

Large, motile, spore-forming Gram-positive rods.

Question 28

How does Clostridium tetani respond to oxygen?

Answer 28

It has extreme oxygen sensitivity; the bacterium is easily killed by oxygen, but its spores can persist

Question 29

class note: Clostridium tetani is challenge to culture. in normal conditions since its extremly sensitive to oxygen

Question 30

What is the main virulence factor of Clostridium tetani?

Answer 30

Tetanospasmin (A-B toxin)

Question 31

What is tetanospasmin and how is it encoded?

Answer 31

Tetanospasmin is an A-B toxin and a plasmid-encoded neurotoxin

Question 32

When is tetanospasmin produced and released?

Answer 32

It is produced during the stationary phase and released on lysis

Question 33

How does tetanospasmin affect the nervous system?

Answer 33

It invades the central nervous system (CNS), binds to motor neurons, and is transported retrogradely to the cell soma

Question 34

What neurotransmitter release does tetanospasmin block?

Answer 34

it blocks the release of inhibitory neurotransmitters (GABA), leading to continuous excitatory neurotransmission

Question 35

What is the function of tetanolysin?

Answer 35

Tetanolysin is a pore-forming toxin

Question 36

What is the primary effect of the tetanus toxin?

Answer 36

Continuous excitatio

Question 37

How does the tetanus toxin cause continuous excitation?

Answer 37

By blocking the release of inhibitory neurotransmitters (GABA)

Question 38

What are the basic characteristics of Clostridium botulinum?

Answer 38

Large, spore-forming, anaerobic rods

Question 39

Where is Clostridium botulinum commonly found?

Answer 39

in soil and water

Question 40

describe the spores of Clostridium botulinum

Answer 40

The spores of Clostridium botulinum are heat-resistant and can germinate in anaerobic (oxygen-free) conditions

Question 41

What disease does Clostridium botulinum cause and what are its symptoms?

Answer 41

Botulism, which causes neurologic symptoms

Question 42

What are the 4 different forms of botulism?

Answer 42

1. Foodborne (canned foods) 2. infant (powdered milk) 3. wound (rare) 4. inhalation (potential biological weapon)

Question 43

How many subunits does the botulinum toxin have and what is their effect?

Answer 43

Seven distinct subunits that cause paralysis

Question 44

What is the function of the B subunit of the botulinum toxin?

Answer 44

It binds to sialic acids and glycoproteins on motor neuron

Question 45

What is the function of the A subunit of the botulinum toxin?

Answer 45

It is a zinc endopeptidase that inhibits the release of acetylcholine (ACh).

Question 46

What is the primary effect of botulinum toxins?

Answer 46

They cause paralysis

Question 47

How do botulinum toxins cause paralysis?

Answer 47

By blocking the release of acetylcholine (ACh) at the neuromuscular junction (NMJ)

Question 48

Where does Clostridium difficile colonize in the human body?

Answer 48

large intestine

Question 49

How is the virulence of Clostridium difficile kept in check?

Answer 49

By normal flora and dimeric IgA

Question 50

What can cause Clostridium difficile to proliferate?

Answer 50

Broad-spectrum antibiotic treatment

Question 51

What range of symptoms can Clostridium difficile cause?

Answer 51

Symptoms can range from relatively benign to severe diarrheal disease (pseudomembranous colitis)

Question 52

Why is Clostridium difficile a major concern in hospital settings?

Answer 52

It produces highly resistant spores, making it a major source of nosocomial outbreaks

Question 53

Why do relapses occur in Clostridium difficile infections?

Answer 53

Relapse due to presence of spores

Question 54

What is the 3 functions of Enterotoxin (Toxin A) produced by Clostridium difficile?

Answer 54

It acts as a 1. neutrophil chemoattractant, 2. stimulates cytokine release 3. disrupts tight junctions

Question 55

What is the function of Cytotoxin B (Toxin B) produced by Clostridium difficile?

Answer 55

It induces actin depolymerization

Question 56

How does increased toxin production affect the virulence of Clostridium difficile?

Answer 56

Increased toxin production, often due to a mutated regulatory gene, leads to higher virulence.

Question 57

How does increased toxin production affect Clostridium difficile's virulence?

Answer 57

Virulence increases with increased toxin production

Question 58

What causes increased toxin production in Clostridium difficile?

Answer 58

A mutated regulatory gene leads to increased toxin production