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Infectious Disease > Intro to Bacterial and Viral Pathogenesis > Flashcards

Intro to Bacterial and Viral Pathogenesis Flashcards

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1
Q

This is the term for a microorganism that is capable of causing disease.

A

Pathogen

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2
Q

This is the term for clinical signs and symptoms of damage that occur as a result of host/pathogen interaction.

A

Disease

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3
Q

This is the term for persistence by multiplying on/within host.

A

Infection

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4
Q

T/F: Most microorganisms are beneficial and not pathogens.

A

True

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5
Q

What do most microorganisms do?

A
  • Protect against harmful organisms
  • Vitamins and nutrients
  • Digestion
  • Develop Immune System
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6
Q

Types of Microbes

A
  • Commensals
  • Opportunistic Pathogens
  • Primary Pathogens
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7
Q

This is a type of microbe that causes disease in a normal host. Survival is dependent on infection not necessarily causing disease.

A

Primary Pathogens

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8
Q

This is a type of microbe where disease is only present if there is a breach in defense. Such as MRSA.

A

Opportunistic Pathogens

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9
Q

This is a type of microbe that is constantly present and depends on humans for existence. In a normal host, there is no disease caused by this.

A

Commensals

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10
Q

What abilities do microbes have that can lead to infection?

A
  1. Breach host barriers and evade immune system
  2. Use biochemical tactics to replicate, spread, establish infection, and cause disease
  3. Transmit to new host
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11
Q

What can we do biologically to control and eliminate pathogens?

A

Use Innate and Adaptive Immune System

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12
Q

Stages of Bacterial Pathogenesis

A
  1. Entry
  2. Adherence
  3. Invasion of Tissues
  4. Avoiding the Immune System
  5. Virulence Factors
  6. Tissue Damage
  7. Transmission
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13
Q

Bacterial Pathogenesis Requirements for Entry

A
  • Must overcome host barriers
  • Compromise of barriers (skin cuts, burns, catheters, ports, sx appliances, IV drug use, smoking, insect bites, antacids, sex)
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14
Q

Common Sites of Entry

A
  • Mouth (ingestion)
  • Nose (inhalation)
  • Respiratory Tract (inhalation)
  • Eyes (contact/splash)
  • Ears (eustachian tube)
  • Urogenital (sex)
  • Anus
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15
Q

Bacterial Pathogenesis Requirements for Adherence

A
  • Attachment to cells
  • Receptor Binding
  • Pili are MAJOR adherence device (determines tissue specificity)
  • E. coli (UTI, P-pili, specific for urinary epithelium, helps prevent urine steam from removing bacteria)
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16
Q

Bacterial Pathogenesis Requirements for Invasion of Tissues

A
  • Invasion
    • Strep and Staph have specific enzymes to help gain entry to tissues
    • Collagenase and Hyaluronidase
  • Degrade through SQ tissues
  • Coagulase - accelerates the formation of a fibrin clot.
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17
Q

T/F: Walled off infection can be reached by immune system or abx

A

False, it cannot.

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18
Q

This is the term for bacteria that live inside eukaryotic cells and uses the sell as a protective factor from the immune system, utilizes endless supply of nutrients and ideal for replication.

A

Intracellular Survival

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19
Q

When a pathogens lives within an eukaryotic cell, what happens?

A
  1. Cause host cell cytoskeleton rearrangement and promotes uptake
  2. In Cytoplasm, it escapes phagosomes (enzyme based)
  3. Avoid acidification of phagosomes
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20
Q

Bacterial Pathogenesis Requirements for Avoiding the Immune System

A
  • Intracellular Lifestyle (antiphagocytic activity)
  • Blockage of signal transduction
  • Antigenic variation
  • Complement Resistance
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21
Q

Antiphagocytic Properties

A
  1. Protein A of S. aureus
    - Binds to IgG and phagocytes can’t bind.
  2. Polysaccharide Capsule
    - Anti-complement (inhibits complement deposition, strep)
  3. IgA Protease
    - Cleavage of IgA (Neisseria, Flu, Pneumonia)
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22
Q

Blockade of Cell Signaling

A
  • Introduce enzymes into phagocytic cells

For example: Yersina and Salmonella block signal transduction leading to phagocytosis and enzymes induce apoptosis

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23
Q

Antigenic Variation

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A
  • Pili are major antigenic molecules

For example: N. gonorrhoeae causes endless array of pili. Over time they change pili and disguise it from the immune system.

24
Q

Complement Resistance

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A
  • Ability to inhibit complement

For example: Salmonella possesses a Lipopolysaccharide inhibiting C5-9 complement and therefore prevents the lysis of the bacterium.

25
Bacterial Pathogenesis Requirements for Avoiding the Immune System
- Exotoxin | - Endotoxin
26
Facts about Exotoxins
- Produces by gram + and - | - Secreted directly by the microbe
27
Exotoxin Proteins Examples: | Corynebacterium Diptheriae
Shuts down ribosomes and blocks protein synthesis leading to cell death
28
Exotoxin Proteins Examples: | Vibrio Cholerae
Alters G-protein function and constitutive activation occurs. It increases cAMP and leads to watery diarrhea.
29
Exotoxin Proteins Examples: | Clostridium Botulinium
Blocks release of acetyl choline from nerve terminal that leads to paralysis
30
Exotoxin Proteins Examples: | Clostridium Tetani
Blocks the release of the inhibitory neurotransmitter glycine so excitatory neurons are unopposed.
31
Facts about Endotoxins
Found only in Gram - Component of Cell Membrane Also known as LPS
32
Effects of Endotoxins
- Fever - Hypotension - DIC - Complement Activation - Activation of Macrophages ***Sepsis!
33
T/F: TNF-alpha is an important plater in shock development.
True
34
Bacterial Pathogenesis Requirements for Tissue Damage
- Can be caused by the host (immune response) - Neutrophil and Macrophage - Proteases and Oxygen Radicals (Lung)
35
Examples of Tissue Damage
1. Post-Streptococcal Glomerulonephritis - - Immune complexes deposited in kidney 2. Rheumatic Fever - - Cross reactivity of Streptococcal antibodies with heart valves
36
Bacterial Pathogenesis Requirements for Transmission
1. Bacteria cause illness to aid in transmission - - Cough to aid in air droplets - - Diarrhea to spread via fecal/oral route. 2. Lethal disease is an accident - - If host dies, the bacteria loses home - - Most highly adopted bugs spare their host.
37
Viral Structure
1. DNA or RNA surrounded by a protein capsid - - Size ranges from 20 to 300nm 2. Can be enveloped or non-enveloped - - Membrane coat derived from host cell 3. Must overtake cell machinery to replicate - - Cannot make energy - - Cannot replicate or make proteins alone 4. Have receptors on the capsid/envelope that allow them to attack specific cells
38
Portals of Viral Entry
- Respiratory Tract - GI Tract - Skin - Genitourinary - Blood - Trans-placental
39
Viral Transmission
1. Person to Person 2. Mother to Offspring (vertical) 3. Animal to Human -- zoonotic infection
40
Components of Viral Infection
- Attachment - Entry - Uncoating - Replication - Assembly - Release
41
Steps of Viral Replication
1. Attachment 2. Entry 3. Uncoating 4a. Transcription 4b. Translation 4c. Replication 5. Assembly 6. Release
42
Components of Viral Infection: | Attachment
Specific proteins on surface of virus attach to specific molecules on the host cell surface. (Can be proteins or carbohydrates)
43
Examples of Attachment: | Influenza
Sialic Acid on Host Cell
44
Examples of Attachment: | EBV
CD3 Receptor on B-cells
45
Components of Viral Infection: | Entry
1. Non-enveloped - - Taken into cells by endocytosis 2. Enveloped - - Fuse envelope with cell membrane - - Fusion of the viral membrane with the plasma membrane - - Releases the nucleocapsid directly into the cytoplasm - - Endocytosis of the viral particle - Release of the nucleocapsid into the cytoplasm
46
Components of Viral Infection: | Uncoating
- - Nucleocapsid must be delivered to the site of replication within the cell - - Most DNA viruses go to the nucleus - - Most RNA viruses stay in cytoplasm
47
Components of Viral Infection: | Replication
- Must have synthesis of mRNA, protein, and copies of genome - DNA viruses use host cell DNA polymerase and RNA polymerase - RNA viruses stay in cytoplasm must either bring or produce a RNA polymerase to replicate and transcribe - Both types of virus use cell ribosomes for translation
48
Components of Viral Infection: | Assembly
- Viruses must assemble themselves - Interaction of proteins, membranes, and nucleic acids - DNA viruses usually assemble in the nucleus and RNA in the cytoplasm - Enveloped viruses acquire membrane from budding off the cell plasma membrane
49
Components of Viral Infection: | Release
- Can be done by lysis, budding, or exocytosis - Naked capsid are usually released by lysis - Enveloped are released by budding often without killing of the cell
50
Viral Spread
- Virus may replicate and remain at primary site - Some may disseminate to other tissues - - Replicate in local tissues
51
The term for when a virus is getting into the blood and travel to secondary sites of viral replication.
Primary Viremia
52
The term for when a virus replicates at secondary site and gets in the blood again
Secondary Viremia
53
Cell Damage
- Most signs and symptoms of viral infection are due to cell death - - Virally induced shut down of macromolecular synthesis (Shut down translation). - - Induce apoptosis - - Immune cytotoxic response (Cytotoxic T-cells kill infected cells)
54
Evasion of Immune Response
- Receptors for cytokines (IL-1 and TNF) - Viruses Block production of cytokines - Block the production of Interferon - Multiple antigenic type
55
How viral infections persist?
- Integration into DNA - Immune tolerance - - Does not make antibodies - Antigenic variation - Spread cell to cell without extra-cellular component - Immunosuppression

Infectious Disease (6 decks)

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