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MICROBIOLOGY: CMOD-Week 1 > (04) Microbial Pathogenesis > Flashcards

(04) Microbial Pathogenesis Flashcards

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1
Q

Define Pathogen

A

A microbe capable of causing disease especially in immunocompetent people

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2
Q

Pathogenesis

A

The mechanism of disease developement

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3
Q

Virulence

A

a measure of a microbe’s ability to cause disease

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4
Q

Virulence Factor

A

any number of products produced by pathogens that allow the microbe to invade, evade host defenses, and/or cause disease

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5
Q

**Differentiate colonization from infection

A

Colonization - Presence and multipication of microorganisms WITHOUT tissue invasion or damage

Infection - colonization that leads to disease

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6
Q

Define Epidemic

A

a disease that rapidly affects many people in a fixed period of time

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7
Q

Define Pandemic

A

a disease that affects people worldwide

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8
Q

Define Endemic

A

Disease that is constantly present at low levels in a specific population

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9
Q

What are Primary Pathogens?

- synonymous term?

A

Pathogens that are ALWAYS associated with disease

Synonym = Frank Pathogens

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10
Q

What are Opportunistic pathogens?

- virulence?

A

Pathogens that are ONLY a problem for immunodeficient people

  • Typically lower virulence
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11
Q

In terms of Primary Pathogens and Opportunistic Pathogens, where do most pathogens fall?

A
  • Somewhere in between
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12
Q
  • *What are the 4 determinants for infection?

- Where applicable indicate if these pertain to innate or adaptive immune system

A
  1. Number of Microorganisms
    - Depends on your exposure
  2. Virulence of Microbe
    - fewer needed for disease if they’re extremely virulent
  3. Host immune status
    - INNATE response
  4. Past immune history
    - ACQUIRED response
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13
Q

What are the stages of bacterial pathogenesis?

A
  1. Transmission
  2. Evasion of Host Defenses
  3. Adherence
  4. Colonization
  5. Spread
  6. Symptoms produced by toxin production or invasion and inflammation
  7. Host Response
  8. Progression or Resolution
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14
Q

What is the incubation period?

- what 5 stages or pathogenesis are within the incubation period?

A

Incubation Period - time period before symptoms are expressed

5 steps during Incubation:

  1. Transmission
  2. Evasion of Defenses
  3. Adherence
  4. Colonization
  5. Spread
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15
Q

What are the 2 general type of symptoms a patient may experience?

A
  1. Prodomal (non-specific)

2. Specific

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16
Q

What are the most common routes of infection?

A
  1. Respiratory
  2. GI (Fecal-oral)
  3. Blood-Borne
  4. Sexual
  5. Maternal-Fetal or Neonatal
  6. Vector- or animal-borne
  7. Fomites, Soil, Water
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17
Q

Respiratory

  • most common infection type
  • ability to control
A
  • Viral Infection = most common

- Hard to control airborne pathogens

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18
Q

GI (fecal oral)

- ability to control

A

Well controlled in 1st world countries

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19
Q

Blood-Borne

- how do these infections typically arise

A
  • IV drug use and Transfusions
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20
Q

Maternal-Fetal or Neonatal Infections

- occur where?

A
  • Infections occuring in utero or perinatal (at the time of delivery)
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21
Q

Vectorborne/animal borne illnesses

  • how are they contracted?
  • Which is most common?
  • Eradication?
A
  • Contracted via Direct Animal Contact
  • MORE OFTEN contracted from arthropod like a mosquito or tick
  • These types of pathogens are hard to irradicate
22
Q

What are the 3 most common portals of entry?

- what do these have in common

A
  1. Respiratory Tract
  2. GI tract
  3. GU tract

**These are areas where the skin and mucous membranes meet

23
Q

What are some of the defenses of the Respiratory Tract?

A
  1. Nasal Turbinates, oropharynx, larynx
  2. Ciliary Epithelia of Lower resp. tract
  3. Mucus, sIgA, Lysozyme, Lactoferrin
  4. Alveolar Macrophages
  5. Upper respiratory tract normal flora
24
Q

What are some of the defenses of the GI tract?

A
  1. Stomach acid, Bile
  2. Peristalsis
  3. GALT
  4. Lysozyme, sIgA, Mucus, Lactoferrin
  5. Normal LOWER GI flora
25
Q

What are some of the defenses of the Genital tract?

A
  1. Low pH
  2. Mucus, sIgA, Lysozyme, lactoferrin
  3. Normal Flora
26
Q

What are some defenses of the Urinary tract?

A
  1. Mechanical Flushing
  2. sIgA
  3. Low pH
27
Q

What mechanism (virulence factor) counters mechanical flushing in the Urinary Tract?

A
  • Ability to Adhere (through pili, etc)
28
Q

Obligate Intracellular Pathogens

- problem with isolating?

A

They usually cannot be cultured for a clinical Dx

29
Q

What are facultative Intracellular Pathogens?

A
  • Grow on Medium but KEY ASPECT of pathogenesis is Hi-jacking a cell

**Hiding in macrophages etc.

30
Q

what does the Type III secretion system have to do with Receptor mediated endocytosis?

A
  • Bacteria that want to become intracellular may inject its own receptor into the host cell so that it can bind and enter the cell
31
Q

Transcytosis

  • what is it?
  • e.g. of what does it?
A
  • Bacteria moves through a cell to enter a new space

- Shigella can travel from gut lumen through M Cell into subepithelial space

32
Q

3 common ways to prevent receptor mediated endocytosis?

A
  • Prevent Fusion with Phagosome
  • Prevent Phagosome fusion with lysosome
  • Prevent acidfication by lysosome
33
Q

What does it mean if an infection disseminates?

  • how can it do this?
  • what is a likely cause of distal disemination?
A
  • Spreads throughout the body

via:

  • Blood
  • Lymph
  • CSF

**Toxin dissemination WITHOUT bacterial spread

34
Q

What are 5 non-toxin virulence factors associated with spread and survival of pathogens?

A
  1. Capsule
  2. Collagenase and Hyaluronidase
  3. Coagulase
  4. IgA protease
  5. Protein A
35
Q

Capsule

  • virulence action
  • how can it be countered
  • common bacteria with it?
  • Disease associated with these bacteria?
A
  • Antiphagocytic
  • Countered by VACCINE-DERIVED antibodies

Commonly in:

  • S. pneumoniae
  • H. influenzae
  • N. Meningitidis

**Commonly associated with meningitidis

36
Q

Collagenase and Hyaluronidase

  • virulence action
  • associated bacteria
A
  • Allow permeation through subcutaneous tissue

- Skin associated bacteria (usually staph)

37
Q

Coagulase

  • virulence action
  • associated bacteria
A
  • Causes blood clot which prevents macrophages from accessing pathogen
  • Staph aureus
38
Q

IgA Protease

  • most active where?
  • Cleaves where?
  • associated bacteria
A
  • Most active on MUCOUS surfaces because its IgA
  • Cleaves at the Hinge Region

Associated Bacteria:

  1. S. pneumoniae
  2. H. influenzae
  3. N. gonorrheae
39
Q

Protein A

  • Virulence Action
  • Associated Bacteria
A
  • Binds to IgG Fc thus preventing the action of the complement
  • Staph Aureus associated
40
Q

What are the 2 types of inflammation?

- associated cells?

A
  1. Pyogenic (pus-producing) - Neutrophils

2. Granulomatous - Macrophage

41
Q

Where do most of our symptoms that arise from viruses come from?

A
  • Our own immune response
42
Q
  • *What are the 3 hallmarks of sepsis?

- what causes sepsis?

A
  1. Low Blood Pressure
  2. Fever
  3. Coagulation
  • Caused by LPS (gram -) or Lipoteichoic acid (gram +)
43
Q

Exotoxins

  • made of?
  • Beneficial Uses?
A
  • Peptides

- Antigenic so inactivated forms (toxoids) can be used for immunization by inducing antibodies

44
Q

What are 4 types of Exotoxins?

A
  1. A-B Exotoxins
  2. Metalloproteases
  3. Pore-forming toxins
  4. Superantigens
45
Q

A-B Exotoxins

  • composition
  • how do they work?
  • examples?
A

Composition:

  1. A subunit - active toxic subunit
  2. B subunits - Binds the toxin to the target
How:
1. ADP-ribosylation of G proteins
(most common) 
2. Alter ribosomes
3. Inhibit protein synthesis

examples:

  • Diphtheria Toxin
  • Cholera Toxin
46
Q

Metalloproteases

  • how do they work?
  • Examples
A
  • Cleave snares blocking neurotransmitter delivery

Examples:

  • botulism - flaccid
  • tetanus - rigor
47
Q

Superantigens

  • how do they work?
  • associated bacteria?
A
  • Bind to MHC II on APCs results in cytokine storm by T-cells

Bacteria:

  1. Staph aureus
  2. Group A Streptococci
48
Q

T or F: many resolved infections lead to life-long immunity

A

True

49
Q

What are 3 general types of unresolved infections?

A
  1. Recurrent Infections
  2. Persistent Infections
  3. Cancer
50
Q

What are 3 reasons why a patient would have recurrent infections?

A
  1. Poor Immune Response (incomplete irradication)
  2. Antigenic Variation (gonorrhea - pili)
  3. Many serotypes
51
Q

What are 2 reasons for persistent infections?

aka ones that go away and come back

A
  1. Chronic Infections

2. Latent Infections (e.g. herpes)

52
Q

What are some cancer causing bacteria and viruses?

A

Bacteria:
- H pylori

Viruses:
- HPV, HBV, HCV, EBV, KSHV, HTLV-1

MICROBIOLOGY: CMOD-Week 1 (10 decks)

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