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Immuno/Micro/Viro > Test 3-5 (Host-Parasite) > Flashcards

Test 3-5 (Host-Parasite) Flashcards

-- List the major microbial virulence factors and mechanisms of pathogenesis -- Understand adherence phenomena & methods for pathogen resistance to phagocytosis -- Describe the role of capsules, biofilms, toxins, superantigens, & destructive enzymes in disease -- Define the importance of exaggerated immune response in the pathogenic effect produced by various microbes in the human host -- List the normal bacterial flora found in the main body regions, and differentiate from adjac

1
Q

bacterial toxins in food incubates…

A

over a few hours pt will have symptoms

THE TOXIN CAUSES THE PROBLEM. NOT AN INFECTION.

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2
Q

severe limiting vomiting and diarrhea are typical of…

A

staphylococcal food poisoning - no antibiotics will help…this kind will pass

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3
Q

toxin that causes tetanus?

A

clostridium tetani - produces the damaging effect on the neurological system

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4
Q

toxin that causes pneumonia

A

stroptococcus pneumoniae (capsule)

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5
Q

seropositive response

A

good immune response to infecting agent

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6
Q

beneficial effects

A
  1. Vitamin Synthesis (vitamin K)
  2. Bile Pigment Degradation
  3. Inhibition of Growth of
    Potential Pathogens
    a. Antigenic priming
    b. Bacteriocin secretion
    c. Low redox potential
    d. Supression of adherence
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7
Q

NORMAL FLORA definition, locations, colonization

A
  • Definition: indigenous microflora part of “healthy” body surfaces
  • Locations: Mouth, upper respiratory tract & gut
  • Colonization: Acquired at birth
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8
Q

Microbiome

A

set of unique human- associated bacteria

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9
Q

Lower respiratory & upper urogenital tracts: -

A

Sterile normally- Susceptible to microbial “invasion” from adjacent sites

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10
Q

incubation time

A

between time of first contact and onset of symptoms

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11
Q

direct exposure

A

skin to skin

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12
Q

aerosol exposure

A

respiratory droplet

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13
Q

fomite exposure

A

towel, doorknob

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14
Q

Virulence factors:

A

any mechanisms used to avoid host’s defenses (term sometimes used to describe any trait that increases virulence)

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15
Q

Invasion

A
  • Some microbes cross mucous membranes or other barriers to reach normally sterile areas
  • Most destroy barrier or penetrate cells
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16
Q

Enteric bacteria and invasion

A
  • synthesize “invasion protein” that promotes binding to M cells in colon
  • Binding causes cells to invaginate, take in bacteria.
17
Q

Bacteria invasion mechanisms

A
  • some spread to adjacent cells (cell-to-cell)

- others move inward to the bloodstream (hematogenous spread)

18
Q

adherence does what?

A

mediates infection. No adherence=no infection.

19
Q

what is the primary mech for attachment of bacteria to tissue surfaces?

A

adhesin on bacteria binds receptor on host

20
Q

where are adhesins usually located?

A

tips of pili for gram-neg bactiea

21
Q

colonization of bacteria is dependent on

A

environmental conditions! temperature or tissue type

22
Q

biofil def and function

A
  • –Bacterial cells (usually many cells) in a sticky web of polysaccharide
  • –Polysaccharide has several functions:
  • Binds bacterial cells together
  • Binds entire biofilm to surface
  • Protects bacteria from antibiotics & host defense mechanisms
23
Q

MICROBIAL SURVIVAL STRATEGIES

A

1) Inhibition of host immune mediators
- -IgA protease - Streptococcus pneumoniae
- -Subverts phagocytosis
- -Capsules prevent ingestion
- -Leukocidins kill PMNs and macrophages
2) Intracellular growth pattern (agent can go inside where immune system cant detect
3) Capsules - shield from microbes from immune response - may use molecular mimicry
4) Avoiding phagocytosis
5) Hiding and growing inside cells (parasites, fungi, viruses)
6) Bait and switch

24
Q

Toxins: Definition

A
  • Bacterial molecules that directly harm tissue or trigger destructive activities
  • Solely responsible for production of symptoms in some bacterial diseases
  • Distributed through bloodstream & able to act systemically; in some cases, bacterium need not enter body at all
25
Q

exotoxin

A

secreted outside the cell

26
Q

endotoxin

A

lipopolysaccharide or LPS (ONLY GRAM NEG)

27
Q

B” subunit …

A

binds to human cellular receptor

28
Q

“A” subunit…

A

is the active portion, poisons host cellular processes

29
Q

Superantigens

A
  • Special groups of toxins; activate T-cells
  • Simultaneously bind to receptor on T-cell & MHC II receptor on another cell (no specific antigen required)
  • Non-specific mechanism for activation of T-cells (i.e., can activate any T-cell)
  • Example: Staphylococcal enterotoxins

Immuno/Micro/Viro (14 decks)

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