Microbial pathogenisis

Question 1

def. pathogenicity

Answer 1

ability of microbe to cause disease

Question 2

def. virulence

Answer 2

traits that render micorbes pathogenic

Question 3

2 general divisions of virulence

Answer 3

1. invasion

2. host damage

Question 4

4 virulence factors involving invasion

Answer 4

1. portal of entry
2. surface colonization
3. surviving host defences
4. portal of exit - transmission to new host

Question 5

3 main sites of entry

Answer 5

1. skin - reuires break
2. mucosa
3. transplants

Question 6

2 ways to surface colonize

Answer 6

1. adhesins - fimbriae, capsues

2. bind to receptors of host and transcytosis

Question 7

2 general classes of host defences

Answer 7

1. non-specific

2. specific

Question 8

3 types of non-specific host defences

Answer 8

1. barriers
2. complement
3. phago

Question 9

2 specific host defences

Answer 9

1. antibody mediated

2. cell-mediated

Question 10

ways to survive complement (2)

Answer 10

1. surface proteins that bind/inhibit complement

2. capsules and biofilms that mask activating substances

Question 11

3 ways to survive phago

Answer 11

1. capsules and biofilms so no access
2. exotoxins kill neutrophils and macros
3. intracellular survival

Question 12

6 ways to survive specific defences

Answer 12

1. immunosupression (HIV)
2. diversion of lymphocyes function - superantigens
3. antigenic variation - change surface antigens
4. proteolysis of ABs - extracellular proteases
5. prevnt opsinization - bind the Fc portions
6. viral latency

Question 13

5 modes of transmission

Answer 13

1. contact (direct or indirect)
2. droplet
3. airborne
4. vector borne
5. common vehicle

Question 14

4 general ways a microbe causes damage

Answer 14

1. due to host response
2. toxins
3. apoptosis
4. mechanical causes

Question 15

potential problems from host reponse

Answer 15

1. inflammation - prostattis
2. rheumatic fever
3. complement - septic shock

Question 16

2 types of toxins

Answer 16

1. exotoxins - secreted by bacteria into surronds

2. endotoxin - part of outer membrane of gram- bacteria

Question 17

5 mechanisms of action of exotoxins

Answer 17

1. help spread in tissue - break down tissues
2. lyse cells - kill WBC or RBC
3. block protein synthesis
4. elevate/supress normal cell function
5. block nerve function - most potent

Question 18

what does tetanus toxin do

Answer 18

• travels up neuron with retrograde transport

- inhibs. release of GABA which is inhibitory neurotransmitter, hence muscle contractions

Question 19

what does botulinum toxin do

Answer 19

• affects peripheral nerve endings
• block presynaptic Ach
• can’t move

Question 20

2 ways to protect against exotoxins

Answer 20

1. vaccinate with toxoids

2. treat with anti-toxins

Question 21

what are endotoxin effects at low and high levels

Answer 21

low - interact with phagos to stim cytokines and cause fever

high - alarming cytokine repsonse leading to shock and intravascular coagulation

Question 22

what is effect of microbes on apop

Answer 22

some prevent ever dying (warts) and some make cell do so prematurely

Question 23

what is mechanical cause of damage

Answer 23

worm blockage - gross

Question 24

what are 2 classifications of pathogens

Answer 24

1. opportunistic

2. true pathogens

Question 25

what are opportinitic pathogens

Answer 25

require some sort of break in the host defences to get in

Question 26

what are true pathogens

Answer 26

able to cause disease despite solid defences

Question 27

how does virulence factor relate to pathogens

Answer 27

true pathogens have more virulence factors

Question 28

what is normal flora

Answer 28

micro-organisms that are normally found on healthy persons

Question 29

4 locations to have normal flora

Answer 29

1. skin 2. resp tract 3. GI 4. GU

Question 30

* 3 normal bact. on skin

Answer 30

1. staphylococcus 2. cornybacterium 3. bacillus

Question 31

* 3 normal bact. in oropharynx

Answer 31

1. neisseria 2. heamophilus 3. candida

Question 32

5 normal bact. in intestine

Answer 32

1. enterococcus 2. E.coli 3. BActeroides 4. Clostridium 5. Candida

Question 33

2 normal bact. in vagina

Answer 33

1. streptococcus | 2. candida

Question 34

4 benefits of normal flora

Answer 34

1. immune stimulation 2. infection prevention 3. human nutrition 4. digestion

Question 35

2 harmful effects of normal flora

Answer 35

1. source of opportunistic infections | 2. source of contaminations in tests