Chapter 8 - Bacteria Flashcards

1
Q

where are adhesins found

A

on bacterium

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2
Q

where are receptors found

A

on host cell

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3
Q

what parts of gram negative bacteria interact with the host epithelial cells

A

bacterial proteins on the tips of fimbriae and/or pili interact with glycolipids and/or glycoproteins of host epithelial cells

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4
Q

what are intimins and what do they do

A

bacterial proteins at the cell surface
- interact with their own translocated intimin receptor (TIR)

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5
Q

what do gram positive bacteria often bind

A

fibronectin which binds to integrins

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6
Q

what are fibronectin binding proteins

A

subclass of a large family of bacterial adhesins referred to as Microbial Surface Components Recognizing Adhesive Matrix Molecules or MSCRAMMS

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7
Q

what are MSCRAMM targets

A

fibrinogen and collagen

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8
Q

what causes greater incidence of pneumonias

A

gram negative bacteria

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9
Q

when individuals are in poor health and fibronectin deficient the balance shifts in favor of_____

A

gram negatives

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10
Q

what do serine rich repeat proteins (SRRPs) do and what bacteria are they associated with

A
  • extend a unique non-repeat domain that mediates adhesion
  • gram-positive bacteria
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11
Q

what does the NR domain bind

A

sialic acid moieties, keratin and other NR domains of a similar SRRP

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12
Q

what are examples of sialic acid binding adhesins

A

oral infectious disease and endocarditis

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13
Q

what is C3a and what does it cause

A

anaphylatoxin (inducer of acute inflammation)

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14
Q

what is C3b and what is it a part of

A

an opsonin and part of C3 convertase and C5 convertase

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15
Q

what is C5a

A

a chemotactic protein for neutrophils and an anaphylatoxin

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16
Q

what are some microbial mechanisms to defend against complement

A
  • addition of sialic acid to lipooligosaccharide inhibits complement fixation
  • C3b peptidase cleaves the complement component into inactive fragments
  • long chain smooth LPS limits access of the MAC to the organism surface
  • polysaccharide capsule masks surface components that can activate complement via the alternate pathway
17
Q

how do pathogens subvert phagocytosis

A
  • inhibit phagocyte recruitment and function
    -Cleave C5a so neutrophils are not attracted
  • increase cAMP to inhibitory levels
  • leukocidins
  • escaping ingestion
    -survival inside phagocytes
18
Q

what are leukocidins

A

enzymes that kill phagocytes

19
Q

how do pathogens escape ingestion

A

-protein A
- expressed on bacterial cell surface
- binds Fc portion of IgG
- bound antibodies cannot act as opsonins

20
Q

how do pathogens survive inside phagocytes

A
  • inhibit lysosomal fusion with phagosome
  • escape into the cytoplasm
  • resist lysosomal enzymes
    -inhibit phagocytes oxidative pathway
21
Q

how do bacteria penetrate nonphagocytic host cells

A

stimulating host cell membrane protrusion

22
Q

what are internalins and what do they interact with

A
  • bacterial proteins at the cell surface
  • interact with host E-cadherin
23
Q

what are invasins and what do they interact with

A
  • bacterial proteins at the cell surface
  • interact with host integrins
24
Q

how do bacteria transmit to other cells

A

actin dependent intracellular motility and intercellular spread

25
Q

how are immune responses subverted

A

-immunosuppression
-superantigens
- changing antigenic coats
- proteolysis of antibodies

26
Q

what do superantigens do

A

divert lymphocyte function