Damage and pathophysiology of microbial disease

Question 1

visible disease is a consequence of what?

Answer 1

Visible disease is a consequence of host
damage

Question 2

How do microbes directly interact with the host to cause disease?

Answer 2

Microbes produce and utilize offensive virulence factors, such as toxins, which destroy immune cells and tissues, thereby promoting spread, transmission, and persistence of the infection.

Question 3

How do microbes indirectly interact with the host immune responses?

Answer 3

Microbes interact indirectly with the host immune system, leading to inflammation, pus formation, kidney malfunctions due to antibody complexes, and endotoxic shock caused by lipopolysaccharides (LPS).

Question 4

What role do microbial interactions with the host immune responses , produce

Answer 4

Work together to produce symptoms

Question 5

What are the main categories of microbial toxins?

Answer 5

The main categories of microbial toxins are exotoxins and endotoxins.

Question 6

Describe exotoxins and their subtypes.

Answer 6

Exotoxins are toxins that are secreted from bacterial cells. They include:

A-B toxins
Site-specific toxins (acting on cell membranes)
Super antigen toxins

Question 7

How can degradative enzymes contribute to microbial virulence?

Answer 7

Degradative enzymes, such as collagenase and hyaluronidase, can facilitate tissue invasion by breaking down components of host tissues, aiding in the spread and colonization of pathogens.

Question 8

How do endotoxins differ from exotoxins?

Answer 8

Endotoxins are cell wall-associated components, while exotoxins are proteins secreted by bacteria into the surrounding environment.

Question 9

What are endotoxins and where are they located?

Answer 9

Endotoxins are intrinsic components of the bacterial or fungal cell wall.

Question 10

which type of bacteria is it associated with lipoteichoic acids ?

Answer 10

lipoteichoic acids found in Gram-positive bacteria.

Question 11

Which type of immune response is triggered by the interaction of endotoxins with the immune system?

Answer 11

Endotoxins overstimulate the immune system, triggering an inflammatory response.

Question 12

What is Lipid A and which type of bacteria is it associated with?

Answer 12

Lipid A is a component of LPS (lipopolysaccharide) and is associated with Gram-negative bacteria.

Question 13

What is zymosan and where is it found?

Answer 13

Zymosan is a component of yeast membranes

Question 14

What potential use do bacterial exotoxins have in vaccine development?

Answer 14

Bacterial exotoxins are targets for vaccine design, specifically in the development of toxoids.

Question 15

How are many bacterial exotoxin genes carried?

Answer 15

Many bacterial exotoxin genes are carried on plasmids or mobile elements like bacteriophages.

Question 16

Which types of bacteria mostly produce exotoxins?

Answer 16

Exotoxins are mostly produced by Gram-positive bacteria.

Question 17

What functions do bacterial exotoxins serve in relation to the host?

Answer 17

Bacterial exotoxins have functions in liberating nutrients from the host and in immune avoidance.

Question 18

what are bacteria exotoxins?

Answer 18

Bacterial exotoxins are soluble,

Question 19

where are the bacterial exotoxins (heat-labile secondary protein metabolites) produced?

Answer 19

heat-labile secondary protein metabolites produced during bacterial growth.

Question 20

What is the role of the A subunit in AB toxins?

Answer 20

The A subunit is the toxic subunit that acts intracellularly on specific mechanisms, often involving ADP-ribosylation.

Question 21

What is the function of the B subunit in AB toxins?

Answer 21

The B subunit serves as the protective or binding subunit. It allows the entry of the A subunit into cells and facilitates its translocation to the cytosol.

Question 22

How does the B subunit determine the specificity of AB toxins?

Answer 22

The B subunit determines cell tropism by binding to specific cell surface receptors.

Question 23

What are some ways in which the B subunit facilitates entry of AB toxins into cells?

Answer 23

The B subunit can induce endocytosis or form pores in the cell membrane. Additionally, it can oligomerize into structures like pentamers or heptamers.

Question 24

what is the mode of action of A-B toxins produce by

Answer 24

C. diptheriae.

Question 25

Describe how A and B components of the Corynebacterium diphtheriae toxin enter the cell? And where the toxic A portion is released in?

Answer 25

A and B components of the Corynebacterium diphtheriae toxin are internalized through endocytosis.the toxic A portion is released
in the cytosol

Question 26

What is the function of the A subunit of the Corynebacterium diphtheriae toxin?

Answer 26

The A subunit of the Corynebacterium diphtheriae toxin is an enzyme that modifies a key protein essential for protein synthesis.

Question 27

What is the consequence of protein synthesis inhibition caused by the Corynebacterium diphtheriae toxin?

Answer 27

Inhibition of protein synthesis ultimately leads to cell death.

Question 28

What are site-specific toxins?

Answer 28

Site-specific toxins are toxins that act specifically at certain sites within the body.

Question 29

where are some neurotoxins produced neurotoxins and how they affect the body

Answer 29

produced at wound sites and cause vomiting by affecting neurons in the gut.

Question 30

How do enterotoxins function in the body?

Answer 30

Enterotoxins directly impact fluid secretion or cause cell death in the gastrointestinal tract. An example is Cholera toxin

Question 31

What is the mode of action of cytotoxins?

Answer 31

Cytotoxins generally target and damage tissue cells directly,

Question 32

What are membrane damaging toxins that cause lysis by disrupting membrane integrity?

Answer 32

Membrane damaging toxins include pore forming toxins and phospholipases.

Question 33

How do pore forming toxins kill cells?

Answer 33

Pore forming toxins kill cells by changing osmotic balance.

Question 34

How do phospholipases contribute to membrane damage?

Answer 34

Phospholipases remove the charged portion of membrane phospholipids.

Question 35

What are super antigen toxins?abd how do they short circuit the immune system?

Answer 35

super antigen toxins are produced by certain bacteria and viruses, such as Staphylococcus aureus. They have the ability to “short circuit” the immune system by allowing non-specific activation of immunity.

Question 36

How do super antigen toxins affect the immune system?

Answer 36

Super antigen toxins activate a large proportion (over 30%) of T cells to produce cytokines, which are chemical messengers. This massive cytokine release can lead to damage of blood vessels, shock, and multi-organ failure.

Question 37

How do degradative enzymes contribute to the severity of bacterial diseases?

Answer 37

Degradative enzymes, often used by bacteria for nutrition, increase disease severity by enabling penetration into deeper tissues, killing cells directly, and destroying tissue structure.

Question 38

What is the non-secreted toxic component found in Gram-negative bacteria?

Answer 38

The non-secreted toxic component found in Gram-negative bacteria is endotoxin.

Question 39

What are some ways toxins disrupt cellular functions?(4ways)

Answer 39

Toxins disrupt cellular functions by:

Increasing cAMP levels and halting protein synthesis.
Inducing lysis through pore formation or membrane disruption.
Hyperactivating processes such as fluid imbalances due to superantigens.
Impacting neurons at synapses, as seen with tetanus and botulinum toxins.

Question 40

What is the causative agent of gangrene?

Answer 40

Clostridium perfringens

Question 41

Describe the characteristics of Clostridium perfringens.

Answer 41

Gram-positive anaerobic rod

Question 42

Where does Clostridium perfringens typically infect?

Answer 42

Deep wounds, especially post-operative infections

Question 43

How does Clostridium perfringens colonize areas of no blood flow?

Answer 43

It can colonize these areas due to its ability to grow anaerobically

Question 44

Why is gangrene caused by Clostridium perfringens difficult to treat?

Answer 44

Treatment is challenging due to limited blood flow in affected areas, making drug delivery and immune response less effective.

Question 45

What distinctive feature is associated with gangrene caused by Clostridium perfringens?

Answer 45

It often produces a foul smell due to the production of volatile amines.

Question 46

Besides α- and β-toxins, what other enzyme does Clostridium perfringens produce?

Answer 46

Collagenase