Microbial pathogenisis Flashcards

1
Q

def. pathogenicity

A

ability of microbe to cause disease

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2
Q

def. virulence

A

traits that render micorbes pathogenic

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3
Q

2 general divisions of virulence

A
  1. invasion

2. host damage

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4
Q

4 virulence factors involving invasion

A
  1. portal of entry
  2. surface colonization
  3. surviving host defences
  4. portal of exit - transmission to new host
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5
Q

3 main sites of entry

A
  1. skin - reuires break
  2. mucosa
  3. transplants
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6
Q

2 ways to surface colonize

A
  1. adhesins - fimbriae, capsues

2. bind to receptors of host and transcytosis

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7
Q

2 general classes of host defences

A
  1. non-specific

2. specific

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8
Q

3 types of non-specific host defences

A
  1. barriers
  2. complement
  3. phago
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9
Q

2 specific host defences

A
  1. antibody mediated

2. cell-mediated

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10
Q

ways to survive complement (2)

A
  1. surface proteins that bind/inhibit complement

2. capsules and biofilms that mask activating substances

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11
Q

3 ways to survive phago

A
  1. capsules and biofilms so no access
  2. exotoxins kill neutrophils and macros
  3. intracellular survival
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12
Q

6 ways to survive specific defences

A
  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
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13
Q

5 modes of transmission

A
  1. contact (direct or indirect)
  2. droplet
  3. airborne
  4. vector borne
  5. common vehicle
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14
Q

4 general ways a microbe causes damage

A
  1. due to host response
  2. toxins
  3. apoptosis
  4. mechanical causes
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15
Q

potential problems from host reponse

A
  1. inflammation - prostattis
  2. rheumatic fever
  3. complement - septic shock
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16
Q

2 types of toxins

A
  1. exotoxins - secreted by bacteria into surronds

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

17
Q

5 mechanisms of action of exotoxins

A
  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
18
Q

what does tetanus toxin do

A
  • travels up neuron with retrograde transport

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

19
Q

what does botulinum toxin do

A
  • affects peripheral nerve endings
  • block presynaptic Ach
  • can’t move
20
Q

2 ways to protect against exotoxins

A
  1. vaccinate with toxoids

2. treat with anti-toxins

21
Q

what are endotoxin effects at low and high levels

A

low - interact with phagos to stim cytokines and cause fever

high - alarming cytokine repsonse leading to shock and intravascular coagulation

22
Q

what is effect of microbes on apop

A

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

23
Q

what is mechanical cause of damage

A

worm blockage - gross

24
Q

what are 2 classifications of pathogens

A
  1. opportunistic

2. true pathogens

25
what are opportinitic pathogens
require some sort of break in the host defences to get in
26
what are true pathogens
able to cause disease despite solid defences
27
how does virulence factor relate to pathogens
true pathogens have more virulence factors
28
what is normal flora
micro-organisms that are normally found on healthy persons
29
4 locations to have normal flora
1. skin 2. resp tract 3. GI 4. GU
30
* 3 normal bact. on skin
1. staphylococcus 2. cornybacterium 3. bacillus
31
* 3 normal bact. in oropharynx
1. neisseria 2. heamophilus 3. candida
32
5 normal bact. in intestine
1. enterococcus 2. E.coli 3. BActeroides 4. Clostridium 5. Candida
33
2 normal bact. in vagina
1. streptococcus | 2. candida
34
4 benefits of normal flora
1. immune stimulation 2. infection prevention 3. human nutrition 4. digestion
35
2 harmful effects of normal flora
1. source of opportunistic infections | 2. source of contaminations in tests