Bac/fungi Pathogenesis Flashcards

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0
Q

Facultative intracellular

A

Can reproduce within and outside of host cell

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria Francisella, Legionella, Yersinia Petis

(see first aid pneumonic)

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1
Q

Obligate Intracellular

A

Can’t make own ATP
Can’t reproduce outside of host cell

Rickettsia
Chlamydia

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2
Q

STEPS OF THE PATHOGENIC CYCLE

A
Exposure & Entry 
Attachment 
Invasion 
Evasion of immune response
Effects on host 
Dissemination/Shedding
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3
Q

Attachment

A

Requires host cell receptors & microbial surface components (Adhesins such as pili/fimbriae, LPS, Lipoteichoic Acid, Mannans)

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4
Q

Invasion

A

Ex: Phagocytosis, endocytosis, cytoskeleton rearrangement (membrane ruffling)

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5
Q

Evasion of immune response

A

Ex)
Compliment evasion = capsules, host cell mimicry, compliment binding proteins, proteases (elastase, C5a peptidase)

Phagocyte evasion = capsules, intracellular parasitism
Antibody evasion = Ig binding/inactivating, antigenic variation

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6
Q

Leukocidins

A

Kills neutrophils and macrophages

Alters phospholipid metabolism by ADP-ribosylation of a protein controlling phosphatidylinositol = disruption of cellular activities

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7
Q

Biofilms

A

Collection of microorganisms that are attached to a surface, covered by a microbially-produced exopolymeric substance (EPS)

Bacteria growing as biofilms can be SIGNIFICANTLY more resistant to antimicrobial agents

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8
Q

Effect on Host

A
  1. Degradative Enzymes (kinases) result in spreading to other tissues
  2. Physical growth through tissues: Fungal growth
  3. Toxic Structures: Lipid A/LPS/Endotoxin
  4. Toxins: exotoxins (-ve), aflatoxin (fungi, carcinogenic), Gliotoxin (fungi, induces apoptosis)
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9
Q

Classes of Exotoxins

A

Class I: membrane binding/acting
Class II: membrane damaging
Class III: Interacellular

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10
Q

Superantigens

A

cause non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release (INF-gamma, IL-2)
Ex: toxic shock syndrome (staph), Rheumatic fever (strep)

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11
Q

Dissemination

A

a) Direct: In surface fluids
- Facilitated by toxin production (Ex: hyaluronidase, etc.)
- Growth through tissues, (fungi)
b) Cross blood-CSF junction (choroid plexus)
c) Blood or blood components
d) Lymphatics/ immune system cells

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