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Host and Defense - Exam 1 > Quiz 2 - Mulvey - Pathogenesis > Flashcards

Quiz 2 - Mulvey - Pathogenesis Flashcards

1
Q

What are opportunists/pathobionts?

A

Under normal circumstance, organism does not cause disease, but can be pathogenic under some conditions

*Immunocompromised

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2
Q

Human microbiota - most bacteria (by number) where in the body?

A

Colon

*Stomach is least moving down thru colon there is an increase

What else increases?

Diversity

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3
Q

What does the microbiota do?

A

Help with digestion

Help protect against infiltration of pathogenic bacteria by taking up space and outgrowing pathobionts (C. diff)

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4
Q

What is colonization resistance?

A

Microbiota inhibits colonization by newcomers

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5
Q

Clostridium difficile is what?

A

Gram (+) obligate anaerobe

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6
Q

What allows c diff to proliferate?

A

Broad spec antibiotic treatment that alters healthy gut microbiota

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7
Q

How does c diff survive antibiotics?

A

Resistance genes and mutations

Biofilm formation

Spore formation

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8
Q

What will c diff sporulate?

A

Shortage of nutrients

*Antibiotic treatments can stimulate spore formation, creating a super shedding state that promotes dissemination of the pathogen

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9
Q

Clostridium spores have a protective coat consisting of what 5 things?

A

Cell membrane

Thick peptidoglycan mesh

Another cell membrane

Wall of keratin-like protein

Outer layer of exosporium

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10
Q

How to kill spores?

A

Autoclaves

*Makes equipment sterile

**Most antibiotics, hand sanitizers won’t kill spores

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11
Q

What two genera form spores?

A

Clostridium

Bacillus

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12
Q

C diff causes what terrible things?

A

Nosocomial infections

Tetanus (C tetani)(soiled IV)

Gas gangrene

Food bourne Infections (botulism, c perfringens)

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13
Q

Bacillus forms what?

A

Anthrax (Soiled IV)

B cereus - food bourne infections

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14
Q

What are 5 factors that facilitate bacterial infection and survival w/in a host?

A

Ability to outcompete commensalism at many stages

Attachment to host cells and tissue via ADHESINS

Evasion of innate and adaptive responses

Acquisition of limiting nutrients - Iron, amino acids

Dissemination w/in a host and transmission to new hosts - Ability to break down or cross tissue barriers

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15
Q

Walk me thru a microbe being phagocytozed?

A

Microbe bound by phagocyte

Phagocyte membrane zips up around microbe and ingests it

That endocytosis leads to lysosome at the phagolysosome

The microbe is killed in the lysosome via proteases and drop in pH

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16
Q

How do some bacteria evade host defenses?

A

Possess virulence factors that prevent uptake and destruction by phagocytes

Possess factors that promote survival in inhospitable places in the body

Facultative intracellular bacteria regulate their genes to know if they are inside or outside a host cell

17
Q

What are some survival strategies w/in extracellular environments?

A

Capsules
-Prevent complement deposition or mask C3b from interaction with phagocytes

Vary surface exposed antigens that allow outgrowth of antigenically novel clones. (Ability to change antigenicity (what it looks like to the host cells) to evade the host via point mutations, etc)(Phase shifting - on/off phase)

Secretion of molecules that interfere with host defenses

  • Toxins
  • Enzymes
18
Q

Some bacteria have mastered survival w/in hosts. Name 4 ways how.

A

Resistant to reactive oxygen species and nitric oxide

Neutralize phagolysosome contents

Prevention of phagolysosome fusion
-Legionella, mycobacterium

Escape from the phagosome
-LIsteria, francisella, rickettsia

19
Q

Tell me about listeria monocytogenes.

A

Gram (+) facultative anaerobe

Causes listeriosis 3rd leading cause of death to foodbourne pathogens

Lettuce or cantaloupes

20
Q

Listeria internalins ________ surface receptors and trigger a cascade. These result in ___________ of the bacteria by host cells that are not considered professional _________.

A

Engage

Internalization

Phagocytes

21
Q

Tell me how listeria uses motility intracellularly.

A

FINISH THIS

22
Q

What are toxins?

A

Virulence factors (excreted or not) that are toxic to human or animal or plant cells

23
Q

Toxins affect host activities. Name some.

A

Aberrant activation of host inflammatory responses (LPS)

Act at host surface or w/in cells to inhibit or activate signaling cascades, alter membrane and protein trafficking
-BoTox

Disruption of host cell membranes, trigger ion fluxes, and alter signaling pathways

24
Q

What is endotoxin?

A

LPS

*Lipid A moiety of LPS

**Body triggers an inflammatory response

25
Q

What are exotoxins?

A

Proteins that are released by bacteria that can cause disease manifestations

26
Q

What are enterotoxins?

A

Act in GI tract to cause infectious diarrhea (Cholera toxin), or food poisoning (Bacillus cereus)

27
Q

What are neurotoxins?

A

Act on nerves/synapses to cause paralysis

28
Q

What are pyrogenic exotoxins?

A

Stimulate release of cytokines that can cause rash, fever, and toxic shock syndrome

29
Q

What are tissue invasive exotoxins?

A

Allow bacteria to penetrate or circumvent cell and tissue barriers (DNAses)

30
Q

Other exotoxins - functions?

A

Many out there. Can affect very specific host factors, though function is not always clear (Anthrax)

31
Q

What are superantigens?

A

Bind class II MHC - recognized by less variant regions of TCR families

*Forms bridge b/t APC and T cells and results in massive outpouring of cytokines - T cells become activated and then exhausted and die

**Can cause diarrhea

32
Q

What is quorum sensing?

A

Allows bacteria to communicate and act in groups (Like in biofilm)

33
Q

Many protein toxins, especially those that act intracellularly consist of 2 parts, the A and B subunits. What are A/B toxins?

A

A subunit - Responsible for the enzymatic activity of the toxin

B subunit - Mediates binding to a specific receptor and transfer of the A subunit across the membrane

34
Q

What are some toxins that are A/B toxins?

A

Diphtheria - ADP ribosylates EF-2 - Inhibition of protein biosynthesis

Shiga - Cleavage of ribosomal RNA - Inhibition of protein biosynthesis

Pertussis - ADP ribosylates G protein - Reduced phagocytosis activity

Cholera - ADP ribosylates G protein - Increased chloride secretion

Botulinum - Cleavage of synaptobrevin - Flaccid paralysis

Tetanus - Cleavage of synaptobrevin - Spastic paralysis

35
Q

How do A/B toxins enter host cells?

A

Fusion w/ endosomes, and release of A subunits triggered by low pH

*Via retrograde transport

36
Q

What is a toxoid?

A

Chemically modified toxin from a pathogenic microorganism, which in no longer toxic, but still antigenic and can be used as a vaccine.

37
Q

Botox?

A
  • Produced by blostridium botulinum
  • Absorbed from stomach after ingestion of contaminated food
  • Inhibits presynaptic release of excitatory NT (Ach) from peripheral nn at neuromuscular junctions
  • Causes flaccid paralysis and respiratory paralysis
38
Q

Tetanus?

A
  • Produced by clostridium tetani
  • Associated with deep wound infections, and it is also a leading cause of infant death worldwide
  • Blocks release of inhibitory NTs (glycine and GABA [gamma-aminobutyric acid])
  • Results in imbalance of excitatory and inhibitory effects of motor neurons
  • Leading to rigid mm contractions and spastic paralysis of respiratory mm

Host and Defense - Exam 1 (14 decks)

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