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Microbiology > Unit 1: Chapter 18 Microbial Pathogenesis > Flashcards

Unit 1: Chapter 18 Microbial Pathogenesis Flashcards

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Biology 101 flashcards
1
Q

Steps of Pathogenesis

A
  1. Entry
  2. Tissue Attachment and Colonization
  3. Immune Avoidance
  4. Host Damage
  5. Pathogen Exit
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2
Q

Pathogens are characterized by the presence of __________

A

virulence factors

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3
Q

Virulence Factors

A

Factors that may help pathogens cause disease in host

The more factors, the more dangerous the pathogen

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4
Q

Adhesion

A

Any microbial factor that promotes attachment

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5
Q

Different types of attachment

A
  • Type I Pili/ Fimbriae
  • Type IV Pili
  • Cell Surface proteins
  • Cell envelope components
    • Capsule
    • Teichoic Acid (gram positive)
    • Components of Outer Membrane (o-polysaccaride can help attach)
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6
Q

Type I Pili/ Fimbriae

A

Static hairline appendages used only for attachment

The tip binds to a specific substrate on host tissue

Fimbriae and nonplus attachment proteins often collaborate to secure a pathogen to a host cell

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7
Q

Adhesion of type I Pili/Fimbriae

A

Step 1/ Initial Binding: Type I plus attaches to the host cell

Step 2/ Secondary (tighter) binding: Cell surface proteins and host cell receptors (integral)

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8
Q

Type IV Pili

A

Dynamic, thin, and flexible

Repeatedly extend and retract allowing “twitching” movement

Tight secondary binding is facilitated by other surface adhesions

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9
Q

Adhesion of type IV Pili

A

Step 1/ Initial Binding: Type IV pili attaches to cell surface and pulls it closer

Step 2/ Secondary (tighter) binding: Surface Adhesions

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10
Q

Bacteria can attach to surfaces in bulk, forming a _______

A

Biofilm

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11
Q

What is a biofilm?

A

A community of bacteria protected by an external called EPS that allows them to live in hostile environments. Formed in nutrient rich environments and will be flushed by water.

Can be made of anything (sugars, proteins, etc)

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12
Q

How is biofilm secreted?

A

By the bacteria

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13
Q

T or F: Biofilms are just single species

A

False

Biofilms can contain both single species or multispecies of bacteria

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14
Q

How do biofilms play an important role in chronic infections?

A

It helps enables persistent adherence and resistance to bacterial host defenses and antimicrobial agents

EPS protects the cell compared to the cells that may be outside the biofilm

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15
Q

T or F: Cell cannot dissolve the EPS and spread

A

False

They can dissolve the EPS and spread

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16
Q

Features of Exotoxins

A
  1. Gram negative and gram positive cells produce exotoxins
  2. Enzymes (proteins)
  3. Sensitive to heat
  4. Secreted by live bacteria
  5. Specific to their target cells (ex. neurotoxin)
17
Q

Features of Endotoxins

A
  1. Only gram negative cells produce endotoxins
  2. Lipid A
  3. Heat- Resistant
  4. Released when bacteria dies
  5. Non- specific
18
Q

___________ are part of the outer portion of the cell wall of gram negative bacteria

A

Endotoxins

19
Q

Endotoxins are engulfed by macrophages which secrete ______

A

Cytokines

20
Q

Endotoxins can cause

A

Very high fever, vasodilation, activate clotting factors, shock, and death if possible

21
Q

What are the targets are bacterial exotoxins?

A
  • Plasma membrane disruption
  • Cytoskeleton alterations
  • Protein synthesis disruption
  • Cell cycle disruption
  • Signal transduction disruption
  • Cell-Cell adhesion disruption
  • Vesicular trafficking
  • Exocytosis
22
Q

What can Staphylococcus alpha toxin cause?

A

Can cause lysis (bursting) of the host cell by disrupting the plasma membrane

23
Q

How does Staphylococcus alpha toxin disrupt the plasma membrane?

A

By forming pores or breaking down membrane lipids

24
Q

What are A-B Exotoxin’s

A

Intracellular Toxins
They bind to a receptor and enter a cell

25
Q

Parts of A-B Exotoxin

A

B (Binding) region

A (Active) portion exerts effects inside

26
Q

A-B Toxin Steps

A
  1. Bacterium produces and releases exotoxin
  2. B (binding) component of exotoxin attaches to host cell receptor
  3. A-B exotoxin enters host cell by receptor- mediated endocytosis
  4. A-B exotoxin enclosed in pinched-off portion of plasma membrane during pinocytosis
  5. A-B components of exotoxin separate.
  6. The A component alters cell function by inhibiting protein synthesis.
  7. The b- component is released from the hostel
27
Q

What are two types of A-B Exotoxins?

A
  1. Diphtheria Toxin
  2. Cholera Toxin
28
Q

What does diptheria toxin do?

A

It blocks ribosome function; cell dies

It creates toxin when there is decreasing amount of iron

29
Q

What does cholera toxin affect?

A

It affects cell signaling inside the cell

30
Q

How does cholera toxin affect cell signaling?

A

Luman has a channel called CTFA that opens when needed to let things in and closes when it doesn’t. Cl+ and Na+ is pumped when channel is open which makes the environment hypertonic and causes H2O to leave. ATP is used to make cAMP and adenylate cyclase helps make it but is not always active. Adenylate cyclase helps make it but is not always active and AC is made by a G-portion which is also not always active. This causes the channel to open.

Basically the G protein is in always on mode, so adenylate cyclase is being produced too much so Na, Cl, and water is being pushed out which leads to diarrhea

31
Q

Is it more difficult to move toxins out a gram negative or gram positive cell?

A

A gram negative cell because toxins have to move out of 2 membranes (the outermembrane and the inner membrane)

32
Q

Type II Secretion System

A

System that uses a pilus like structure as a piston to ram proteins through the outer membrane pore structure

Pushes protein out in piston manner from inner membrane to periplasm to outer membrane

33
Q

What type of energy does type II secretion use?

A

ATP

34
Q

Type III Secretion

A

Some microbes use tiny molecular syringes embedded in their membranes to inject proteins directly into the host cytoplasm

Basically sticks the protein directly into the host cell and goes into the cytoplasm of the host directly; no receptors are required so it makes it easy to infect

35
Q

Type IV pili helps aid in _______

A

Pathogenesis

36
Q

What type of bacteria is is there a wide range of type IV pili?

A

Gram Negative

37
Q

Can biofilms live in in any surface, living or non living?

A

Yes they can live on both living and non living surfaces and the biofilm allows for them to live in hostile environments

38
Q

What tissues do biofilms cause the most chronic infections?

A

Oral, lung, and urogenital

39
Q

Type I Pili/Fimbriae E.coli Binding

A

Step 1/ Initial Binding: Attach to the host

Step 2/ Secondary Binding: Via cell surface proteins AND it injects the receptor into the cell

Tir proteins

Intimin proteins then attach

Microbiology (7 decks)

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