Lecture 67 - Microbial pathogenesis

Question 1

define commensal

Answer 1

colonizer, normal, benign

Question 2

define pathogen

Answer 2

causes disease, either opportunistic or obligate

Question 3

define pathogenicity

Answer 3

relative ability of a pathogen to cause disease

Question 4

define virulence factors

Answer 4

molecules that increase efficiency of infection of disease severity

Question 5

what are the 5 virulence factor actions? give examples.

Answer 5

1. colonize (adhesins)
2. invade (invasins)
3. evade barriers and defense (enzymes)
4. suppress immune response (enzymes)
5. acquire nutrition (siderophores)

Question 6

what are the portals of entry

Answer 6

1. ingestion
2. inhalation
3. ascending
4. direct contact/cutaneous penetration

Question 7

what are the alimentary system defenses

Answer 7

1. mucus secreted by goblet cells
2. acidic pH environment
3. MALT/GALT/Peyer’s patches
4. microfold (M) cells
5. IgA

Question 8

what are respiratory system defenses

Answer 8

1. mucociliary clearance
2. surfactants
3. BALT
4. IgA
5. alveolar macrophages

Question 9

what are skin defenses

Answer 9

1. thick physical barrier
2. dryness + acidity
3. cool temperature
4. sebum
5. Largerhaan cells

Question 10

which is an important component of microbial defense in the skin

Answer 10

dry, acidic environment

Question 11

what are the 4 steps of bacterial pathogenesis

Answer 11

1. adhesion
2. colonization
3. invasiveness
4. toxigenesis

Question 12

what are 3 adherence factors

Answer 12

1. adhesins
2. pili
3. fimbriae

Question 13

what releases iron from intracellular stores for bacterial utilization

Answer 13

siderophores

Question 14

what is lipopolysaccharide

Answer 14

• endotoxin
• stimulates host immune response
• can stimulate excessive levels of cytokines

Question 15

what are exotoxins

Answer 15

• enzymes
• toxins altering intracellular/regulatory pathways
• neurotoxins or superantigens

Question 16

describe clostridium botulinum

Answer 16

• disruption at the neuromuscular junction
• cleaves SNARE proteins (accumulation of AcH)
• flaccid paralysis

Question 17

describe Clostridium tetani

Answer 17

• neural-neural junction
• inhibition of glycine release
• spastic paralysis

Question 18

pathogenicity islands

Answer 18

virulence genes present in clusters on bacterial chromosome

Question 19

what are the 3 routes of horizontal gene transfer

Answer 19

1. transformation
2. transduction
3. conjugation

Question 20

what are the toxins produced by Bacillus anthracis

Answer 20

1. edema factor
2. protective antigen
3. lethal factor

Question 21

what is associated with toxins produced by Clostridium tetani

Answer 21

inhibition of GABA and glycine at the neural-neural junction

Question 22

tropism depends on

Answer 22

presence of viral receptors on host cells

Question 23

what are the 5 outcomes of viral replication

Answer 23

1. lysis
2. apoptosis
3. persistence/latency
4. proliferation
5. malignant transformation

Question 24

what are viral virulence factors

Answer 24

1. evasion
2. caspases
3. viral toxins

Question 25

antigenic drift

Answer 25

natural and spontaneous mutations

Question 26

antigenic shift

Answer 26

formation of a new virus with mixed genes

Question 27

which is a characteristic of some viral infections

Answer 27

formation of syncytial cells

Question 28

fungal virulence factors

Answer 28

1. cell wall 2. capsules 3. glucans/glycoproteins 4. antioxidants 5. toxins

Question 29

describe the 4 steps in fungal pathogenesis

Answer 29

1. cell wall/capsule and other virulence factors 2. protection of microbe against defense mechanisms 3. fungus not removed/degraded 4. chronic inflammation

Question 30

describe prions

Answer 30

transmissible protein aggregates lacking an infectious genome

Question 31

what is converted in prion disease

Answer 31

normal cellular prion protein to the abnormal form

Question 32

T/F: prions cause gross lesions

Answer 32

FALSE