Chapter 2 and 18

Question 1

What age group is most susceptible to infectious disease

Answer 1

very young (under 3) and very old (over 60)

Question 2

What factors put a person at risk for developing a infectious disease?

Answer 2

age, host genetic makeup (receptors), host hygiene and behaviors, nutrition and exercise, pre-existing conditions, occupation, immune status and immunopathogenesis.

Question 3

In order to prevent colonization, what three mechanisms does the body use?

Answer 3

lungs: mucociliary escalator= moves pathogens out

bladder: detrusor contraction= propels urine with tremendous force

intestines: peristaltic action= constant flow

Question 4

What is the first step of pathogenesis?

Answer 4

attachment or adhesion

Question 5

what are two types of adhesins?

Answer 5

Pili adhesins and non-pili adhesins

Question 6

characteristics of pili adhesins?

Answer 6

they have hairlike appendages - tips with receptors for host cells

Question 7

What do adhesins help with?

Answer 7

colonization and biofilm formation

Question 8

what is a Fimbriae?

Answer 8

a pilli

Question 9

how do non-pilus attach to host?

Answer 9

cell wall proteins that bind to host proteins like integrin or fibronectin cause a more intimate relationship.

Question 10

Pili are made up of (a) ___________ pilin protein (b) ____________

Answer 10

a) identical
b) subunits

Question 11

the tip of the pilus contains adhesion protein that binds host cell ____________

Answer 11

a) receptors

Question 12

Bordetella pertactin is a example of what host protein?

Answer 12

integrin

Question 13

streptococcus protein F is a example of what host protein?

Answer 13

fibronectin

Question 14

streptococcus protein M is a example of what host protein?

Answer 14

fibronectin and the completement regulatory factor H

Question 15

Neisseria meningitidis uses what type of pili?

Answer 15

IV pilli -> Neisserial Opa nonpilis membrane proteins

Question 16

What does a microbe detect to determine if it is in a host or not? (5 things)

Answer 16

1) temperature
2) Iron levels
3) Magnesium levels
4) pH levels
5) Hormones

Question 17

If a microbe detects it is in a host cell what will it being to express?

Answer 17

Virulence genes

Question 18

what type of pathogen is more likely to have interactions with the host immune system?

Answer 18

extracellular pathogens

Question 19

What type of pathogens are less likely to be detected by the immune system?

Answer 19

intracellular pathogens because they are inside the host cell.

Question 20

facultative intracellular pathogens

Answer 20

can live either inside host cells or free from them

Question 21

What are four ways extracellular pathogens avoid the host immune system?

Answer 21

1) capsules
2) cell surface proteins
3) surface antigens
4) cell-cell communication (quorum sensing)

Question 22

what do capsules do?

Answer 22

coat bacterial cell walls and can prevent phagocytes from binding.

Question 23

how does the immune system eventually circumvent the avoidant strategy of capsules?

Answer 23

immune defense mechanisms can eventually circumvent this avoidance strategy by producing opsonizing antibodies (immunoglobulin G) against the capsule itself

Question 24

How does cell surface proteins on S.aureus sequester antibodies to aid in immune avoidance?

Answer 24

Protein A can bind to the Fc region on antibodies which hides the pathogen from phagocytosis

Question 25

What are the two ways Protein A binding to the Fc site of antibodies hides the pathogen from phagocytes?

Answer 25

1) causes the antigen-binding sites to point away from the microbe. 2) if the antigen-binding site binds to one bacterium, protein A from a second bacterium can bind to the Fc region and block phagocyte recognition

Question 26

Salmonella can _________ to change flagellin A to flagellin B and confuse the immune system.

Answer 26

a) vary surface antigens.

Question 27

Cell-cell communication (quorum sensing) helps pathogens evade the immune system by creating fake cytokines, what do the cytokines do to prevent attack of the pathogen?

Answer 27

These fake factors can manipulate the balance of helper T cells and send immunity down the wrong path for combating the microbe

Question 28

autoinducer molecule will a) ________ as the number of bacteria grow

Answer 28

a) rise

Question 29

when the pathogen detects increased levels of a autoinducer, what will it do next?

Answer 29

turns on virulence gene expression

Question 30

what are three examples of facultative intracellular pathogens?

Answer 30

salmonella, shigella and listeria

Question 31

pathogens that invade and reproduce inside a host cell only

Answer 31

Obligate intracellular pathogens

Question 32

three examples of Obligate intracellular pathogens?

Answer 32

Rickettsia, coxiella, bartonella

Question 33

what are the three fates of intracellular pathogens?

Answer 33

fate 1= THRIVE UNDER STRESS fate 2= INHIBITING PHAGOSOME-LYSOSOME FUSION fate 3= ESCAPE FROM THE PHAGOSOME

Question 34

Fate 1: In order to survive inside the host cell, bacteria's such as Coxiella burnetii allow themselves to be engulfed by lysosomes (phagosome- lysosome fusion) in which they than differentiate into a form able to replicate in the phagolysosome which results in?

Answer 34

Inclusion bodies

Question 35

Fate 2: Pathogens like salmonella can remain inside a phagosome and ________________?

Answer 35

prevent fusion with the lysosome

Question 36

Fate 3: Pathogen such as shigella and listeria can a) _________________ and than move throughout the b) _________________ into adjacent cells by forming c) _________________

Answer 36

a) break out of the phagosome b) cytoplasm c) actin tails

Question 37

Microbial exotoxins are categorized on the basis of their?

Answer 37

cellular targets and mechanisms of action

Question 38

Part of the outer membrane of the Gram-negative cell wall that includes LPS?

Answer 38

Endotoxin

Question 39

When is endotoxin released?

Answer 39

When Gram negative pathogens die.

Question 40

what symptoms are triggered by the "cytokine storm" inflicted by endotoxins?

Answer 40

Fever, activation/depletion of clotting factors (petechiae), activation of complement, vasodilation, shock or death.

Question 41

what classification of cells secrete exotoxins?

Answer 41

both gram negative and postive

Question 42

what classification of cells secrete endotoxins

Answer 42

gram negative cells only

Question 43

where does the pathogen C. diphtheriae remain in the body?

Answer 43

the pharynx

Question 44

When is the C. diphtheria toxin released?

Answer 44

conditions with low levels of iron!