Chapter 8 - Bacteria

Question 1

where are adhesins found

Answer 1

on bacterium

Question 2

where are receptors found

Answer 2

on host cell

Question 3

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

Answer 3

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

Question 4

what are intimins and what do they do

Answer 4

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

Question 5

what do gram positive bacteria often bind

Answer 5

fibronectin which binds to integrins

Question 6

what are fibronectin binding proteins

Answer 6

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

Question 7

what are MSCRAMM targets

Answer 7

fibrinogen and collagen

Question 8

what causes greater incidence of pneumonias

Answer 8

gram negative bacteria

Question 9

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

Answer 9

gram negatives

Question 10

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

Answer 10

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

Question 11

what does the NR domain bind

Answer 11

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

Question 12

what are examples of sialic acid binding adhesins

Answer 12

oral infectious disease and endocarditis

Question 13

what is C3a and what does it cause

Answer 13

anaphylatoxin (inducer of acute inflammation)

Question 14

what is C3b and what is it a part of

Answer 14

an opsonin and part of C3 convertase and C5 convertase

Question 15

what is C5a

Answer 15

a chemotactic protein for neutrophils and an anaphylatoxin

Question 16

what are some microbial mechanisms to defend against complement

Answer 16

• 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

Question 17

how do pathogens subvert phagocytosis

Answer 17

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

Question 18

what are leukocidins

Answer 18

enzymes that kill phagocytes

Question 19

how do pathogens escape ingestion

Answer 19

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

Question 20

how do pathogens survive inside phagocytes

Answer 20

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

Question 21

how do bacteria penetrate nonphagocytic host cells

Answer 21

stimulating host cell membrane protrusion

Question 22

what are internalins and what do they interact with

Answer 22

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

Question 23

what are invasins and what do they interact with

Answer 23

• bacterial proteins at the cell surface
• interact with host integrins

Question 24

how do bacteria transmit to other cells

Answer 24

actin dependent intracellular motility and intercellular spread

Question 25

how are immune responses subverted

Answer 25

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

Question 26

what do superantigens do

Answer 26

divert lymphocyte function