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Disease processes > Bacteria pathogenesis > Flashcards

Bacteria pathogenesis Flashcards

Week 2

1
Q

Pathogen

A

organisms capable of causing disease

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2
Q

Disease

A

clinical signs and symptoms of damage that occur in a host as a result of its interaction with an infectious agent

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3
Q

Overt/strict pathogens

A

only associated with human disease, not found as members of normal microbial flora.

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4
Q

Opportunistic pathogens

A

members of normal flora that only cause disease when in the right conditions/introduced into unprotected sites.

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5
Q

Facultative pathogens

A

can grow and survive in the environment as well as in the host. doesn’t have to cause disease to survive in environment (the ‘accidental host’)

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6
Q

what do virulence factors do?

A

facilitate the colonisation, growth and spread of bacteria in host

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7
Q

Areas of the body that should be microbe free

A

fluids: blood, CSF, urine

Tissues/organs: muscles, glands, brain etc

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8
Q

LD50

A

lethal dose 50: dose that gives 50% mortality in animal model

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9
Q

infective dose vs lethal dose

A 
ID = dose at which you get infection
LD = dose at which you die
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10
Q

Sub-clinical infection

A

Bacteria are present but no pathology

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11
Q

Name 6 examples of virulence factors in bacteria

A
  1. Adhesins: fimbriae, pili, outer membrane proteins
  2. Flagella for motility
  3. Help to obtain essential nuritents (e.g. siderophores)
  4. Toxins
  5. Capsule
  6. Type III secretory molecules
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12
Q

Give an ex of a bacteria which is an extracellular pathogen

A

Streptococcus pneumoniae

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13
Q

Ex of toxin producing bacterium

A

Clostridium botulinum
Clostridium tetani
Vibrio cholera
E.coli

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14
Q

Ex of an intracellular bacterium

A

Salmonella enterica serovar Typhimurium

Listeria monocytogenes

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15
Q

Virulence factors of S.pneumoniae

A 
Capsule
Surface adhesions
Secretory IgA protease
Neuroaminidase
Pneumolysins (pore forming)
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16
Q

Endotoxin

A

On bacteria surface

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17
Q

Ex of endotoxin

A

LPS on Gr- bacteria

18
Q

What receptor can detect LPS?

A

TLR4 (toll-like receptor 4)

19
Q

What is LPS an example of?

A

PAMP

20
Q

General symptoms of LPS

A

fever, diarrhoea, vomiting

21
Q

Ex of bacteria that has LPS endotoxin

A

Salmonella

22
Q

Exotoxin

A

Toxin released extracellular

23
Q

Which is generally more toxin, endo or exo toxin?

A

Exotoxin

24
Q

Which is generally more heat stable, endo or exo toxin?

A

Endotoxin

25
Q

Enterotoxin

A

group of exotoxins that act on the small intestine

26
Q

Ex of bacterium that release enterotoxins

A

C.dif
Cholera toxin
E.coli

27
Q

Toxoid

A

inactivated toxin useful as a vaccine

28
Q

Which bacteria has beta-haemolysin?

A

Streptococcus pyogenes

29
Q

Botulinum toxin is an example of a…

A

Neurotoxin

30
Q

Clostridium botulinum is a…

A

G+, spore forming anaerobe

31
Q

Symptoms of botulinum toxin

A 
flaccid paralysis (floppy baby)
Respiratory arrest
32
Q

What does botulinum toxin do?

A

Blocks release of Ach

33
Q

Clinical use of botulinum toxin

A 
Relief of spasticity
Chronic migraine
Excessive sweating
Overactive bladder
Botox
34
Q

Is vibrio choleae Gr- or Gr+?

A

Gr-

35
Q

What does cholera toxin do?

A
  • conformational change of G protein
  • adenyl cyclase constantly activated
  • increase cAMP
  • Cl- and Na+ into lumen, water follows
36
Q

Cholera toxin results in

A

massive loss of fluid and electrolytes

37
Q

4 strategies used by bacteria to evade immune system

A
  • Hide: intracellular
  • Antigenic variation and phase variation: change immunogeneicty to avoid established immune response
  • Molecular mimicry
  • Modify or block host response
38
Q

3 ex of bacteria modifying/blocking host immune response

A
  1. capsule - phagocytosis
  2. IgA protease - antibody
  3. Type III secreted effectors - cell signally
39
Q

Ex of pathogen which undergoes molecular mimicry

A

Haemophilus influenzae

40
Q

Molecular mimicry may trigger…

A

Autoimmunity

41
Q

Extra genome sequence, regions of DNA unique to a set or related pathogens usually transferred via horizontal gene transfer =

A

Pathogenicity islands

Disease processes (21 decks)

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